Textile Laundering Technology

TEXTILE LAUNDERING TECHNOLOGY By Charles L. Riggs,'Ph.D. and Joseph C. Sherrill, Ph.D.

TEXTILE RENTAL SERVICES ASSOCIATION O F AMERICA

a 199OTextileRentalServices Association ofAmerica. All Rights Reserved.No pa^ of this book may be copied or reproduced in any form or by any meanswithoutwritten permissionfrom the Textile Rental Serv~cesAssociation of America.

1130 E. Beach Blvd. Hallandale, FL 33009

DEDICATION

CONTENTS

The authors dedicate this edition of Textile Laundering Technology to Everett E . Harris in appreciation for his guidance and assistance not only during the preparation of this edition but also the first edition in 1979. Ev has been a constant source of enthusiasm. inspiration. and personal assurance for both of the authors during these and other TRSA-sponsored projects for many years . Thanks Ev!!

LIST O F TABLES AND FIGURES ........................................... 5 ACKNOWLEDGMENTS ...................................................... 7 INTRODlJCTION .............................................................. 9 l/LAUNDRY CHEMISTRY An Introduction to Basic Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Chemical Processes in Laundering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Tests of Chemical Concentrations in Laundering Operations . . . . . . . . . . . . 15 The Decergency Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Washroom Test Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Washreom Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Wash Test Piece Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 P/WATER . Source? of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 Water Impurities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 Water Softening for Laundering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3/WASHING CHEMICALS Surfactants ..................................................................35 Alkalies ..................................................................... 42 Other Washing Chemicals .................................................50 4/BLEACHES Stain Removal .............................................................. 53 Bleach Types and How They Remove Stains .............................. 54 Sterilizing with Bleach ..................................................... 54 How Chlorine Bleach Affects Textile Strength Loss in Cotton ........... 55 Recommended Use of Liquid Chlorine Bleach ............................. 55 Bleach Management in the Laundry ...................................... 57 5/FINISHING CHEMICALS Antichlor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 . Sours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 . Fabric Softeners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 .

Chemicals T h a t Control Mildew and Bacteria .......................... 65 Sizing ...................................................................... 68 Soil-release Finishes ......................................................70 Proprietary Finishing Chemicals ........................................ 70 G/TEXTILE FIBERS. FABRICS. AND FINISHERS Classification of Textile Fibers ...........................................71 Fiber Names .............................................................. 71 Natural Fibers ............................................................ 72 Textile Labels ............................................................. 73 Common Fibers Encountered in Professional Laundries ................73 Structure of Fibers. Yarns. a n d Fabrics ................................. 81 Textile Dyeing. Printing. and Finishing ................................. 86 7/LAUNDRY PROCEDURES Prewash Steps .............................................................89 Wash Steps ................................................................ 92 General Laundry Formulas ............................................... 98 Item Classifications ...................................................... 104 Chemical Supplies ........................................................ 114 Chemical Selection .......................................................114 Dyeing Textiles in the Plant ............................................. 119 8/SAFE HANDLING O F WASHROOM CHEMICALS Chemical Handling ....................................................... 121 Chemical Storage ......................................................... 122 Hazard Communication Standard .......................................122 9/PROBLEM SOLVING AND TROUBLESHOOTING Troubleshooting Typical Operating Problems ............................127 Causes of Textile Damage .................................................130 Tests for Damage .......................................................... 136 Tests for Bacteriological Growth ..........................................138 Stain Removal Methods ...................................................139 lO/LAUNDRY AND THE ENVIRONMENT Water Pollution ............................................................145 Water and Energy Conservation ..........................................147 Air Pollution ............................................................... 149 ll/WASHING AND FINISHING EQUIPMENT Conventional Washing and Finishing Equipment .......................151 Tunnel Washing ...........................................................156 GLOSSARY .................................................................. 163 APPENDIX ...................................................................183 INDEX ....................................................................... -203

LIST OF TABLES AND FIGURES

TABLES: T a b l e 2-1:Degree to which water can be softenedminimum hardness attainable. ppm a s CaC03.......................... 3 0 T a b l e 3-1:Comparison of surfactant types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4. 0 T a b l e 3-2:Common alkaline builders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 5 T a b l e 3-3:Solid alkaline silicate ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 7 T a b l e 4-1:Effect of chlorine bleach on general soil removal . . . . . . . . . . . . . . .53 T a b l e 4-2:Effect of available chlorine solutions on cotton fabric .......... 55 T a b l e 4-3:Chlorine bleaches ................................................58 T a b l e 4-4:Oxygen bleaches .................................................6 0 T a b l e 5-1:Common laundry sours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3 . T a b l e 7-1:Soil classification by item . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90 T a b l e 7-2:Ratio of soiled to clean weight for various textile classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92 T a b l e 7-3:Sour guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9. 7 T a b l e 7-4:Very-light-soil formula ..........................................100 T a b l e 7-5:Light-soil formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 T a b l e 7-6:Medium-soil formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 . T a b l e 7-7:Heavy-soil formula .............................................-102 T a b l e 7-8:Very-heavy-soil formula ........................................ 103 T a b l e 7-9: Industrial shirt formula ......................................... 107 T a b l e 7-10:Industrial pants formula ...................................... 108 T a b l e 7-11:Mat formula .................................................... 110 T a b l e 7-12:Shop towel formula ............................................112 T a b l e 7-13:Printer towel formula .......................................... 113 T a b l e 7-14:Chemical makeup of selected detergent powders ............. 115 T a b l e 7-15:Liquid sodium silicate formulas ............................... 117 T a b l e 7-16:Liquid potassium silicate formulas ........................... 118 T a b l e 9-1:Chemical damage to cotton caused by common medicines .... 131 T a b l e 9-2:pH values of foodstuffs ..........................................132 T a b l e 9-3:Stain removal procedure for unknown stains ..................141 T a b l e 9-4:Stain removal procedure for reducible stains .................. 142

What You Should Know About Laundering and Textiles written by P. Eugene Smith and Pauline Beery Mack. Much of the material in these two texts, prepared under the direction of the Texas Woman's University, was identical or based on the same studies a s used to prepare editions of Textile Laundering Technology. The first edition of Textile Laundering Technology written by Charles L. Riggs and Joseph C. Sherrill was published in 1979. The first edition was reprinted in 1982 and 1987. This second edition represents a complete rewriting and update. This text incorporates still-valid material t h a t appeared in the previous editions. The authors have relied heavily on manufacturers, distributors, and suppliers for information on the most recent developments in the textile and laundry industries. TRSA's Production and Engineering Committee is grateful to Dr. Charles Riggs and Dr. Joseph Sherrill for their efforts in preparing this volume, thereby recognizing our industry's need for a comprehensive text on textile laundering technology. Industry members are urged to acquaint themselves with the contents of this book and to make certain that their washroom supervisors and managers use it regularly. Mark Dmlet Chairman TRSA Production and Engineering Committee

LAUNDRY CHEMISTRY

T

he trend toward increased scientific analysis, application, and control h a s made a n impact on the textile maintenance industry. Very careful analysis and control of all phases of the washing process have become necessary because of the increasing cost of energy, water, a n d chemicals. New developments in detergents, textile fibers and blends, and textile finishes, a s well a s improvements in laundering techniques, reemphasize the need for textile rental business owners and managers to become more familiar w i t h the fundamental principles and applications of laundry chemistry. This chapter explains basic tests commonly used in the washroom to determine chemical concentrations of wash formulas and how soils are removed from textiles.

AN INTRODUCTION TO BASIC CHEMISTRY Chemistry deals with the composition of materials and the processes that b r i n g about changes in their composition. The most basic materials we ordinarily deal with are known a s chemical elements. Iron, copper, sulfur, and carbon a r e examples. The atoms of two or more different elements may be combined i n various ways to form molecules or chemical compounds. An atom is sometimes defined a s the smallest particle t h a t can enter into combination with another atom to form a molecule or a compound. A molecule is the smallest particle that can exist free and alone and still possess the properties of the c o m ~ o u n d . Chemical elements are commonly represented by a capital letter and in some cases a n additional lowercase letter. This abbreviated form is called a symbol. A compound is represented by a group of element symbols called a formula. Examining the formula of a compound reveals not only the elements composing the compound, but also the ratio of atoms in the elements combined in t h e compound. For example, sodium orthosilicate, a n alkaline salt commonly used t o enhance detergency in laundry practice, is represented by the formula Na,SiO,. This formula shows t h a t the compound is made up of the elements

sodium (Na),silicon (Si), a n d oxygen (0)combined in the ratio of four atoms of sodium to one atom of silicon and four atoms of oxygen. Laundering chemistry requires frequent reference to chemical elements and compounds. Symbols and formulas may be regarded a s chemical shorthand. Some examples of elements a n d their symbols, plus compounds and their formulas occurring in substances commonly encountered in laundering are: ICalcium (Ca)-calcium bicarbonate or Ca(HCOJ,. This compound is found in hard water. It destroys the action of soap through the formation of calcium soaps (lime soaps) that are relatively insoluble in water and cause soap specks (insoluble precipitates), a rancid odor, a n d fabric discoloration. Most synthetic surfactants are less effective in hard water but may not form insoluble precipitates. IC a r b o n (C)-cellulose or (C,,H,,O,Jx. A material found widely in many natural products. Cotton, linen, a n d rayon fibers are made up almost entirelv of this comvound. The subscript x may have a value of up to 12,000 and indicates t h a t this combination of atoms is joined end to end to create a long molecule called a polymer. IC h l o r i n e (C1)-sodium hypochlorite or NaOC1. This is the active element of chlorine bleach solution. W F l u o r i n e (F)-sodium acid fluoride or NaHF,, sodium silicofluoride or Na,SiF,, a n d ammonium silicofluoride or (NHJ2SiF6. These compounds are used in laundering a s sours. Sours are used in the final step of the laundering process to neutralize the last traces of alkali from soaps and builders left in textiles from previous steps in the laundry procedure and from alkalinity occurring naturally in raw or softened water. W H y d r o g e n (H)-water or H,O. Water is the single most important material used in the laundry industry. Acetic acid or CHJOOH. All acids contain hydrogen. This acid sometimes is used a s a laundry sour. W I r o n (Fe)-ferric oxide or Fe,O,. One of the constituents of rust stain. Ferric hydroxide or Fe(OH),. This compound is a n ingredient of rust found in water. W Magnesium (Mg)-magnesium bicarbonate or Mg(HCOJ,. This substance often is present in hard water. Like the corresponding calcium compound, it destroys the usefulness of laundry soap and reduces the effectiveness of many surfactants. O x y g e n (0)-hydrogen peroxide or H,O,. An agent frequently used in the laundry a n d in the textile industry a s a n oxidizing bleach. W P h o s p h o r o u s (P)-sodium tripolyphosphate or Na,P,O,,. This substance is used often a s a sequestering agent t h a t chemically combines with other agents to inhibit a n undesirable reaction. W Silicon (Si)-sodium metasilicate or Na,SiO, and sodium orthosilicate or Na,SiO,. Both of these compounds are alkaline salts and are used a s builders in the laundry formula. S o d i u m (Na)-sodium hydroxide or NaOH. This compound, also known a s caustic soda, is used in some laundry formulas where concentrated alkalinity is required. Compounds containing sodium are used widely in the ---

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laundry industry and other industries because of their solubility in water and their low cost relative to other metal salts. IS u l f u r (S)-sulfuric acid or H,SO,. This important compound is used i n titration a n d laundry washroom control tests. Even small amounts of t h i s substance can cause serious damage to cotton and other fibers containing cellulose. Sodium hydrosulfite dihydrate or Na,S20,.2H,0. A chemical agent used a s a n antichlor and a s a dye stripper.

CHEMICAL PROCESSES IN LAUNDERING The chemical processes involved in laundering are measured and described using terms such a s alkali (base) or alkalinity, acid or acidity, neutralization, pH, and titration. These terms describe properties of water that contain acid o r alkali. When a n acid, a n alkali (base), or a salt is dissolved in water, its molecules divide in part or completely into simpler particles called ions. These ions a r e electrically charged. Ions with a negative (-) electrical charge are called anions while ions with a positive (+) electrical charge are called cations. The chemist defines a n alkaline substance, or a n alkali, a s one t h a t in a water solution yields negatively charged hydroxide (OH) anions. Alkaline substances, when dissolved in water, produce a slick feel to the touch, turn red litmus paper blue, and give solutions a pH value greater than 7.0. Alkalies react with acids to form salts. Sometimes the term "base'' is used interchangeably with "alkali." Sodium carbonate, sodium metasilicate, sodium orthosilicate, caustic soda, sodium tripolyphosphate, and ammonia are alkalies. Some of these compounds, such a s caustic soda (NaOM), actually contain the hydroxide (OH) anion. Alkaline salts, such a s sodium metasilicate, produce solutions containing OH anions through a n interaction with water, described a s hydrolysis. An acid substance is one t h a t yields hydrogen (H+) cations in water solution. The ions in this case are positively charged. These substances characteristically impart a sour taste to water and produce water solutions that turn blue litmus paper red and have a pH value of less than 7.0. The two general types of acids are mineral (inorganic) acids and organic acids. Under the inorganic or mineral group are sulfuric, hydrochloric (muriatic), nitric, phosphoric, and hydrofluoric acids. Under the organic group are acids such a s acetic (component of vinegar), formic, oxalic, and many others. The organic acids mentioned above a t one time or another were widely used a s souring agents. Some compounds, such a s sodium silicofluoride and ammonium silicofluoride, are not actually acids since they don't yield hydrogen ions directly. When these materials are dissolved in water, they produce hydrogen cations and form solutions with distinctly acid characteristics that are useful for laundry souring. Neutralization is a chemical reaction in which a given quantity of a n acid, either mineral or organic, reacts with a chemically equivalent amount of alkall to form water and a salt. Every laundry makes use of the process of neutralization in the sour bath. In

this portion of the laundering formula, a definite quantity of sour (acid substance) is added to neutralize the alkalinity naturally occurring in the raw or softened water and any residual alkali from soap or alkaline builder used in the laundering operation. pHis the term applied to a scale of values designating the degree of acidity or alkalinity of a solution. The pH scale runs from zero to 14. The middle point on the pH scale, 7.0, represents the neutral point. At this neutral point the number of hydrogen (H+) cations and hydroxide (OH-) anions is equal. A substance with a pH of 7.0 is considered neutral, since it is neither acid nor alkaline. As the pH value of a substance drops below 7.0, the concentration of hydrogen cations increases. The greater the number of hydrogen cations, the lower the DHvalue. Conversely, a s a substance increases in hydroxide anions, the higher the pH value. pH scales are logarithmic in character. For example, a solution a t pH 11is ten times more alkaline than a pH 10 solution and 10,000 times more alkaline than a pH 7 neutral solution a s illustrated in Figures 1-1 and 1-2.

Figure 4-4: Acidity and alkalinity of water solutions 0 Alkalinity B Pure Water El Acidity

pH value

Figure 1-2: pH of increasing alkaline solutions

- 10.000 times the alkalinity of pH 7

- 1,000 times the alkalinity of pH 7

- 100 times the alkalinity of p H 7 - Neutral solution

TESTS OF CHEMICAL CONCENTRATIONS IN LAUNDERING OPERATIONS Historically, laundering chemical use has been based on the amount of supplies needed to launder 100 pounds of textiles. Supplies are added a t recommended lev& by sing calibrztcd measuring scoops, premeasured packages, or controlled injection. To determine if the proper supplies have been added, samples of the water drained from a bath are titrated to test the amount of a chemical present in percent or parts per ndlion (ppm) of the total water present in the bath. It's important to note that inconsistent results are often seen from one machine to another. Two factors are responsible for these inconsistencies: 1. The amount of water (pounds) used to launder 100 pounds of textiles, or the fabric-to-liquor ratio, changes based on the design of the washer (e.g., amount of clearance between cylinder and shell), water level setting, fiber content of the textiles, and mechanical problems (e.g., leaking fill or dump valves). 2. Some chemicals are consumed during the bath, and titration values change with the,consumption. In many cases, the consumption amount will change with time and/or temperature. Titration and pH tests are used to describe alkaline solutions. A simple expla-

nation for both is that the titration value indicates the total amount of alkali present while t h e p H valueindicates the intensity of the alkaline solution. The two values are related to each other only when the chemical elements of the alkali are known. This concept is explained in more detail in Chapter 3. Titrationis an analytical procedure used to determine the amount of acertain chemical substance in a solution. The amount of the substance is determined by measuring the volume of a standard solution (a solution containing an accurately known amount of chemicals) required for complete reaction. Titrations are rapid and convenient. They can be used in the laundry washroom to determine: H the active and total alkalinity (sodium oxide) in the suds and rinse waters. H the hardness and bicarbonate alkalinity of the incoming water and of softened water, and Ithe percentage of available chlorine in chlorine bleach solutions. The pHof a solution can be determined in a number of ways. The most common way is with a n acid-base indicator, which is an organic dye exhibiting a certain color through one range of pH (either acid or alkaline) and another color through another range. Acid-base indicators such a s phenolphthalein, methyl orange, and methyl purple show rather distinct and abrupt changes of color a t a certain pH value and are commonly used for acid-alkali titrations in general laundry practice. Phenolphthalein is colorless below pH 8.3 and becomes a reddish violet color at higher pH values. Methyl orange is rose red below pH 3.0 and turns a yellow color from pH 4.6 upward. Methyl purple is purple below pH 4.8 and turns green at pH 5.4 and above. With other acid-base indicators, the color of the indicator in a solution of unknown pH is compared with the colors of a set of standards. The pH of the solution can be found by matching the color of the solution of unknown pH with one of the colors in the set of standards. Other methods for measuring pH values-electronic pH meters and paper pH testers-will be discussed in later sections.

THE DETERGENCY FUNCTION Eight physical chemistry functions are frequently used to define the detergency function: diluting, wetting, neutralizing, dissolving, saponifying, emulsifying, deflocculating, and suspending (prevention of redeposition). fl Diluting. Dilution removes suspended soil from the washer by lowering the concentration of soil in each bath. Dilution occurs with each drain and fill and is frequently monitored to evaluate the effectiveness of rinsing. With conventional washers, when the water is dumped, soil is removed. The water in the next bath has less soil to suspend. Dilution depends on the total amount of water in the washer for each batch and the amount of water retained by the load after draining. IWetting. Wettingis the penetration of water into the fabric structure. Penetration is enhanced by surfactants and high temperatures. Wetting action provides the contact between washing chemicals and soil.

B Neutralizing. Most soils are acidic in nature. The action of alkalies negtralizes these acids. H Dissolving. Soluble soils are removed by the solvent action of water. T h e

solubility of many soils is increased by high temperature, high pH, and t h e presence of washing compounds. H Saponifying. Organic fats and oils can react with the alkalies used in washing. This reaction-saponification-forms soaps that are more water soluble than are the fats and oils. The soaps formed by saponification also help remove other soils from textiles. Emulsifying. Mineral oils and greases can't be saponified. These soils must be removed through the action of the alkali and/or surfactant which breaks the globules of mineral oil into very small particles that are surrounded by the emulsifying agent. Once emulsified and dispersed in t h e water, mineral oils are removed by dilution. Deflocculating. Solid soils such as carbon, dust, earth, and clay must b e broken down into smaller particles-deflocculated or peptized-dispersed, and removed. Surfactants and complex phosphates shorten the amount of time necessary to release solid soil from textiles. H Suspending a n d p r e v e n t i n g redeposition. Once soils are removed a n d dispersed, they must remain so until rinsed away. Alkali and/or surfactants keep the soil suspended in the water. Poor suspending power allows the soil to redeposit on textiles, frequently in the form of specks or overall graying. The effectiveness of these eight processes is controlled by varying four factors of the washing process: 1. mechanical action, 2. chemical type and concentration, 3. temperature, and 4. time. Detergency doesn't work without mechanical action. Regardless of time, washing temperature, and detergent composition and concentration, soil won't be removed from the fabric until mechanical action is applied in the presence of water, allowing loosened soil to be removed by dilution. Mechanical action provides the movement of the textiles in the washing cylinder and the flow of water through them. For any given piece of equipment, the principles governing mechanical action, such a s cylinder and rib design, are usually fixed. Therefore, variations in mechanical action are primarily controlled by thelength of cycle time, proper machine loads, and correct water levels. Some machines offer variable-speed rotation. A second factor is the composition and concentration of chemicals used in the process. These have a key role in penetrating the oil-waterinterface, allowing mechanical action to free the loosened soil particles. The chemical action of washing chemicals is described in more detail in Chapter 3. A third factor is laundering temperature. Generally, the higher the temperature, the greater the detergency. Increased temperature promotes mobility of' washing compounds and soil particles by lowering the surface and intcrfhcial tension and the viscosity of the water. Increased temperature also increases

WASHROOM TEST KIT EQUIPMENT AND CHEMICALS The following equipment and chemicals should be included in a washroom test kit. 1. T M o n and other testing equipment W Titration containers, marked at 25 ml Titration containers, calibrated at 1. 2. 5. 10. 15, 20 and 25 ml W Pipets, calibrated 0.5 ml W Plastic dropping bottles1,60 ml, containing reagents listed below W Plastic bottle, 30 ml, wide mouth W Plastic spoon, 0.05 g capacity 2. General W Long-handleddipper W Maximum registering thermometer (to 220°F) W Tape measure 3. Reagents' W Sulfuric acid, 1.0 N ( ~ 1 1(standardized) ) W Sulfuric acid, 0.1 N (N/10) (standardized) IPhenolphthalein indicator. 0.5%solution in 50%ethanol: pH range 8.3 to 10.0 W Methyl orange indicator. 0.1%solution; pH range 3.2 to 4.4 I Sodium thiosulfate, 0.28 N (standardized) W Hydrochloric acid. 10%solution W Potassium iodide. 10%solution W Potassium thiocyanate, 10%solution W EDTA (sodium (di) ethylenediamine tetraacetate). standardized hardness titrantJ1 mg CaC03/ml Ericchrome Black T. 0.5%in sodium chloride (dry) IHardness buffer solution. pH 10.0 Orthotolidine, 0.1%solution in 10%hydrochloric acid W Universal indicator solution, pH range 4 to 10 4. pH measurement methods W Universal indicator (pH 4 to 10) used primarily for sour determinations W pH test papers a. Wide range, pH 1O . to 12.0 b. Shortrange.pH3.9to5.4.5.0to6.6.6.1 to7.4.7.2to8.8.8.4to9.4.9.1 to10.4, 10.1 to 12.0 c. Electronic pH meter with standard buffer solutions: pH 4, 7, 10. 'The calculations shown on the following pagesassumea delivery rate of 20 drops per milliliter.Note: Not all dropping bottles deliver at 20 drops per milliliter.The dropper bottles in theTRSATest Kit are standardizedand the reagent is adjustedto compensate for expected variances. 2Manyof the tests require accurately standardized solutions obtainable from TRSA. test kit manufacturers, or chemical supply houses. Tor water hardness determinations, a standard soap solution may be used as an alternative. Periodic standardization is required to correct for evaporation.

the activity of the chemicals, making them faster acting and more efficient. Most of the chemical reactions involved in laundering will double in reaction speed for each increase of 18°F. The fourth factor is time,which can be regulated by adjusting the minutes each cycle runs. These four factors work together. Their role is thought to be interrelated in the form of a pie. The four factors share the total pie; if any one factor is reduced, one or more of the others must be increased in order to maintain the whole. In addition, total detergency can be increased by increasing any one or all of the individual factors. Excessively reducing any of the four factors can harm detergency, but increasing a factor beyond the optimum range won't produce the expected improvement.

WASHROOM TEST KIT A washroom test kit is essential for properly controlling the use of laundry chemical supplies. The test kit should contain hardware and chemicals needed to perform titrations, determine pH, and detect residual chemicals in textiles. Available washroom test kits have the accuracy and ruggedness to withstand everyday use in the washroom. One such test kit can be procured from the Textile Rental Services Association of America (TRSA). Subassemblies of the complete kit are also available and can be replaced inexpensively if used up or damaged or lost in the plant.

WASHROOM TESTS Determining water hardness Water hardness is tested by accurately measuring 5 milliliters of water into a graduated vial. Add two drops of hardness buffer solution. Add one spoonful of Ericchrome Black T. If the solution is blue, stop; the water contains no hardness. If hardness minerals are present, the solution will develop a wine red color. If wine red, add hardness titrant, counting the drops, until the color turns blue. Add the titrant slowly, since this reaction isn't instantaneous. Each drop of hardness titrant is equivalent to 10 parts per million of hardness expressed a s calcium carbonate (CaCO,). Water hardness in grains per gallon may be determined by dividing parts per million by 17.1. Example: 30 drops of EDTA titrant are required to titrate 5 ml of water 30 (10 ppm CaCO, hardnesddrop) = 300 ppm hardness 300 ppm divided by 17.1 = 17.5 grains per U.S. gallon Determining water alkalinity Alkalinity of water is determined by titrating with standardized acid using methyl orange indicator. Accurately measure 25 milliliters of the water to be tested into a titration container. Add four drops of methyl orange indicator and agitate. If the solution is yellow, add N/10 acid drop by drop while stirring until the color changes to pink. Each drop of acid is equivalent to 12.2 parts per million of bicarbonate (HCOy)alkalinity.

Example: 15 drops of N/10 acid are required to titrate 25 ml of water 15 (12.2 pprn (HCO; drop) = 183 pprn HCO; alkalinity Determining break and suds alkalinity

Both alkalinity and pH can be measured a t the break (the first wash cycle in which supplies are added). The alkalinity is measured by titrating with N/1 (1.0 N) acid and calculated a s sodium oxide (Na20)content. Either phenolphthalein or methyl orange (or both) may be used a s the indicator. The methyl orange titration measures total alkalinity, and the phenolphthalein titration measures active alkalinity (available above pH 8.3). The significance of active and total alkalinity is described in Chapter 3. Accurately measure 25 milliliters of break or suds water to be tested into a calibrated titration vial. Add four drops of phenolphthalein; red color results. Add N/1 acid, counting the drops, while agitating, until the indicator changes from red to colorless. Each drop of N/1 acid is equivalent to 62 parts per million of sodium oxide (Na,O) active alkalinity. Record this result. Add four drops of methyl indicator; solution becomes yellow. Continue adding N/1 acid until the color changes to pink. Record this result. Example: 12 drops of N/1 acid are required to titrate 25 ml of suds water to the phenolphthalein endpoint. An additional seven drops are required to reach the methyl orange endpoint. Calculation: 12 (62 ppm/drop) = 744 pprn active alkali 7 (62 ppm/drop) = 434 pprn inactive alkali 19 (62 ppm/drop) = 1,178 pprn total alkali Determining the alkalinity of the final rinse

The alkalinity of the final rinse is determined by titrating a s described above. Titrating the first and second rinses with N/1 acid is usually appropriate. Any additional rinses are titrated with N/10 acid. The final clear rinse should yield a titration no more t h a n 120 parts per million alkalinity (10 drops of N/10 acid) higher than the plant supply. Determining the available chlorine in bleach

The strength of a bleaching agent must be controlled carefully to achieve optimum stain removal with minimal damage to the textiles. Dry organic chlorine bleach is very stable and needs to be checked only periodically. However, liquid bleach is unstable in storage a n d should be checked daily before using or, if this isn't practical, a t least twice a week. Bleach strength is measured by titration, which can be conducted on the dilute stock solution, on the concentrated carboy solution, or on dry bleach a s received. To test a dilute stock solution (1.0 percent available chlorine recommended), use a calibrated dropper to transfer 0.5 milliliter of the bleach solution into the titration flask. Add 25 milliliters of water, 10 drops of 10 percent hydrochloric

acid, and 10 drops of 10 percent potassium iodide. The solution will turn brown, indicating the presence of available chlorine. Add 0.28 N sodium thiosulfate b y drops until the solution becomes and remains colorless. Each drop is equivalen t to 0.1 percent available chlorine. Example: 11 drops of 0.28 N sodium thiosulfate are required to titrate 0.5 ml of bleach 11 (0.1% Cl/drop) = 1.1% or 11,000 pprn available chlorine To test concentrated liquid bleach, use a calibrated dropper to transfer 0.5 milliliter of concentrated bleach to a calibrated titration container. Fill with water to the five milliliter mark and agitate. Transfer 0.5 milliliter of this mixture i n t o a second titration flask a n d analyze a s described in the preceding paragraph. Each drop of sodium thiosulfate is equivalent to one percent available chlorine in the concentrated liquid. Example: 10 drops are required for the titration 10 (1.0% Cl/drop) = 10% available chlorine To test dry bleach, accurately weigh and thoroughly dissolve one ounce of d r y bleach in exactly one pint of water. Any undissolved material may be disregarded since all of the available chlorine will be dissolved. Analyze 0.5 milliliter of this mixture a s described in the first procedure above. Each drop of 0.28 N sodium thiosulfate is equivalent to 1.67 percent available chlorine in the d r y bleach. Example: 12 drops are required for titration 12 (1.67% Cl/drop) = 20% available chlorine Measuring pH

The pH of the bleach bath can be measured in the following ways: pHmeters are relatively inexpensive, fairly rugged, and portable. They may be direct dial reading, but most frequently are digital. They mav be battery or line ( 1 1 0 ~operated ) a n d are supplied with chemical buffer solutions for quick and continuous standardization. Aclean probe is immersed into a buffer solution (pH 4,7, or lo), standardized according to manufacturer's instructions, rinsed with t a p or softened water, a n d then placed into the bath to be tested. Many of the pH probes are temperature sensitive a n d require an appropriate adjustment. The pH is read directly. pHpapers are the most portable and inexpensive testing method available, but also the least reliable. A set of pH test papers usually consists of a roll of wide-range indicator paper (pH 1 to 12) and several rolls of narrow-range pH papers. To use the paper method, place a drop of the solution to be tested on the wide-range paper. Compare the color of the paper to the color standards on the paper dispenser to obtain a n approximate pH value. From this approximate value, select the short-range paper t h a t covers the range of the approximate pH. Place a drop of the solution on the short-range paper a n d compare the resultant color of the paper to the short-range standard for a more precise pH measurement.

The exact ranges of pH test papers may vary with manufacturers. Sample ranges for pH test papers are indicated below: TEST PAPER RANGES

I I I 1 I I

pH range

Standard readabllHy

When used

1 to 12

Nearest whole pH

To determine approximate pH

10.7 to 14.0

Nearest 0.3 pH

Break bath (alkaline formulation)

10.1to 12.0

Nearest 0.3 pH

Break bath (low alkaline formulation) and bleach bath

9.1 to 10.4

Nearest 0.3 pH

Bleach bath

8.4 to 9.4

Nearest 0.3 pH

Water testing

7.2 to 8.8

Nearest 0.3 p H

Water testing

6.1 to 7.4

Nearest 0.3 pH

Sour bath

5.0 to 6.6

Nearest 0.3 pH

Sour bath

3.9 to 5.4

Nearest 0.3 pH

Sour both

-

Estimatina bleach pH . by- titration If pH meters and papers aren't available, bleach pH can be estimated. Use the procedure outlined for determining break and suds alkalinity with the phenolphthalein indicator only. Interpretation is based on the fact that when the titration falls between one and five drops, the pH of the bath is between 10.2 and 11.1. Results with this method depend on the nature and strength of the alkali being used. Orthosilicate and metasilicate range from 10.5to about 11.1for one to five drops N/1 acid. Milder alkalies, those containing significant quantities of soda ash, will fall between 10.2 and 10.8for the one to five drops of N/1 acid. While this method doesn't provide a direct reading, it gives a good estimate of the pH of the bleach bath. When the phenolphthalein indicator colors the solution red, the pH is a t least 10, since the red color begins to disappear below this level. Evaluating bleach in rinses

All of the bleach added to the washer a t the bleach bath must be removed or exhausted in order to avoid chemical damage to fabrics. Tests with orthotolidine provide a rapid way to detect bleach carryover. Add four drops of orthotolidine solution to a water sample from the rinse cycle immediately preceding the sour bath. A yellow to brown color indicates the presence of chlorine. Higher levels of bleach carryover cause a darker color. The amount of chlorine added by municipal treatment plants frequently yields a yellow color when tested with orthotolidine. For this reason, all tests of rinse water should be compared with the color of the supply water test because the rinse water can't be expected to exceed the quality of the supply water.

Some textiles retain chlorine even though the test on the rinse water is negative. Use the same orthotolidine test on textiles; but because of the acidic nature of the test, be sure to thoroughly rinse the orthotolidine from the textiles immediately after testing. Depending on the pH, orthotolidine may also yield a yellow color with oxygen bleaches. Operators should note that false positive results may occur in the presence of certain metals and algae. Estimating sour pH The pH of the soured goods determines whether they are ready for finishing. This is conveniently measured by dropping Universal Indicator on a section of the moist fabric. The dropper should not come in contact with the fabric. Compare the color observed on the fabric to a standard color chart. Determining iron accumulation in textiles

The presence of iron in textiles usually results in fabric discoloration and/or tensile strength loss. To determ&e the presence of iron, moisten the fabric with a drop of 10percent hydrochloric acid. To the wet spot, add a drop of 10 percent ammonium thiocyanate. A pink discoloration indicates the presence of iron in the fabric. The darker the color, the more iron. This test is very sensitive and produces positive results with iron levels lower than needed to produce iron staining. It requires experience to judge whether the iron concentration is high enough to be a problem. The test chemicals should be rinsed from the fabric to avoid damage. WASH TEST PIECE SERVICES Washroom test pieces are designed to measure overall performance of the washing formula. Different types of test pieces are available from several organizations serving the textile maintenance industry. TRSAl offers a one- and a five-wash test piece. Both test pieces use dyed swatches that produce color changes or disintegrate, depending on the amount of heat, alkali, or bleach the sample has been exposed to. The one-wash self-evaluating test reveals the effects of bleach, alkali, heat, and mechanical action and is a fast way to evaluate formulas, supplies, or procedures. The five-wash test piece is returned for laboratory analysis, which includes inspecting and evaluating the dye swatches plus instrumental measurements of tensile strength loss, whiteness, and grayness. The International Fabricare Institute (IFI)' offers a one-wash test piece that, Textile Rental Sewices Association of America 1130 E. Hallandale Beach Blvd., Suite B P.O. Box 1283 Hallandale,FL 33008-1283 International Fobricare Institute Laboratory and Research Center 12251Tech Rd. Silver Spring, MD 20904

after laundering, i s returned to the institute for analysis. The analysis provides instrumental measurements of tensile strength loss and whiteness retention, a s well a s soil and stain removal. The Department of Fashion and Textiles of Texas Woman's University3 offers a 20-wash test piece for cotton and cotton/polyester formulas that is returned to the university for analysis. The test piece is analyzed for soil removal (based upon standard artificial soil), whiteness retention, and tensile strength loss. Results are compared to performance goals based on soil classification. Test pieces designed to measure mechanical action are available through Testfabricst These are self-evaluated pieces and help determine optimum mechanical washing conditions such a s proper loading. Testfabrics also provides a wide variety of artificial soil swatches that are useful in evaluating chemical and mechanical action.

WATER

A

lthough it's commonly accepted t h a t soiled laundry gets clean by a combination of time, temperature, chemical action, and mechanical action, t h e truth i s t h a t water is the single most important chemical used in laundering. Its role is to remove soil from the textiles by the processes of dissolving and dilution. Time, temperature, chemical action, and mechanical action serve to enhance t h e role of water in removing soil. Water's ability to dissolve a wide variety of substances makes it a n effective cleaning agent for a large percentage of soils. Most substances are more soluble in water than in any other solvent. Detergents and "builders" (described in detail in Chapter 3) have been developed to enhance the cleansing action provided by water in the presence of mechanical action. Water allows the action of the washer to be distributed throughout the soiled load. It acts a s a wetting agent penetrating the soil/fiber interfaces and removing the soil from the fabric. Water also carries chemical supplies to and from the textiles and c a m e s away suspended soil. Water i s used in large quantities in all laundries. Water consumption per pound of work processed varies from less t h a n one gallon per pound for light soils to more than four gallons per pound for very heavy soils. This chapter describes sources of water a n d the impurities launderers have to contend with in the laundering process.

3

Deportment of Fashion and Textiles Texas Woman's University P.O.Box 22509, TvVU Station Denton, TX 76204

Vestfabrics. Inc. P.O. Drawer 0 200 Blackford Ave. Middlesex. NJ 08846

SOURCES OF WATER Pure water is the logical choice for cleaning because of its universal solvent action. Pure water freezes a t 32OF (O°C) and boils a t 212OF (lOO°C). Absolutely pure water is very rare and expensive to produce. It's soft; absolutely colorless, odorless, and tasteless; and is neutral with a pH value of 7.0. Water found in nature is always contaminated with dissolved or suspended gases, liquids, and solids. Water follows a never-ending cycle. A vast amount of water from oceans, lakes, and waterways evaporates into the air. I t then condenses and returns to the earth's surface a s rain, snow, or some other form of precipitation. It runs

over or under the surface of the earth and finally finds its way back to a n original source - a lake, ocean, or waterway. Water evaporates in a relatively pure form, but it immediately begins to pick up impurities a s it flows through the cycle. Water falling a s precipitation is fairly soft; however, it contains dissolved gases and suspended particles. The level of air pollution directly affects the quality of water falling a s precipitation. Once water reaches the earth, it begins to collect soluble impurities and, in many cases, exchanges one type of impurity for another. Air pollution in the form of oxides of sulfur or nitrogen lower the pH of water falling a s precipitation - a condition referred to a s acid rain. The acidity makes water corrosive and able to dissolve a large number of substances such a s iron, developing higher levels of dissolved impurities. Water can be temporarily diverted from the cycle and used for drinking, cooking, laundering, or industrial purposes. Water is present in a n almost constant amount, and it's very doubtful we'll ever run out of it. However, water quality and location are of immediate concern. Water is diverted from its original cycle as either ground water or surface water. Surface water includes reservoirs, lakes, rivers, streams, ponds, or creeks. Surface water is generally replaced more rapidly by water's natural cycle than is ground water. Ground water falls to earth a s precipitation and then seeps into the ground and later appears a s springs or remains in underground lakes and rivers. The amount and kind of impurities in a water supply depend on many factors, including temperature of the water, turbidity and turbulence of flow, solubility of the matter it comes in contact with, the size and density of particles it encounters, and the chemical nature of other impurities in the water.

WATER IMPURITIES Problems created by impurities depend on the type of industry using the water. Only impurities of concern to the laundry industry will be discussed in this chapter. Water impurities can have a major impact on the quality of textiles washed by a laundry. Since the amount and kind of water impurities vary greatly, each laundry operator must evaluate treatment needs on an individual basis. The following impurities must be reduced or avoided by laundries.

Hardness Hard water contains dissolved calcium and magnesium salts. Water hardness is reported in terms of grains per U S . gallon or parts per million (ppm) of calcium carbonate equivalents (CaCOJ. One grain per gallon equals 17.1 ppm. Soap loses its effectiveness i n hard water because hard water turns soap into insoluble curds t h a t have no surfactant properties to remove and suspend soil. Most synthetic surfactants don't produceinsoluble curds in hard water, but the efficiency of most surfactants is reduced by water hardness. Water softening treatment is usually less expensive than using larger amounts of detergents. Some municipal water treatment plants reduce the level of hardness of the processed water a s a service to their users. Some treatment plants increase the hardness of the water by adding coagulating agents.

Chlorine Chlorine, especially in bleaches, is a very common ingredient in laundering, but it's regarded a s an impurity in the water supply. To meet federal, state, and local requirements for safe drinking water, most municipalities add chlorine to the water distributed to homes and businesses. The required chlorine content a t the most distant point in the distribution system is from 0.5 to 2.5 ppm. If the laundry is near the treatment plant, the added level of chlorine can measure several parts per million. Chlorine content higher than 0.5 ppm degrades many types of water-softening resins. The level of residual chlorine may need to be lowered by a reducing agent such a s sodium sulfite before the water passes through the water softener. Iron Water containing a s little a s 0.2 ppm iron can discolor laundry. Iron can enter the water a t the source or be picked up from rusty water lines and tanks. Iron is usually a soluble, colorless form called ferrous iron. When exposed to air, ferrous iron rapidly converts to insoluble ferric iron, which can vary in color from yellow to reddish brown. Since the allowable level of iron in drinking water is much higher than for laundry use, treating for iron in the laundry with water pretreatment or rust removing sour may be needed. In addition to staining problems, iron can accelerate the action of some chemicals such a s bleach, damaging textiles. Alkalinity Alkalinity isn't a problem during laundry suds steps, but high levels of bicarbonate alkalinity can adversely affect rinsing. If the water used for rinsing and souring is alkaline, the rinse steps won't neutralize the alkalinity sufficiently and sour (acid) amounts will need to be increased. Acidity For proper laundering, the water should be neutral or slightly alkaline. In some parts of the country, water supplies are acidic because of acidic industrial and domestic wastes and, occasionally, seepage into ground water of acidic deposits i n deep mine shafts. Some energy recovery devices t h a t introduce combustion gases into the water can also create acidic water conditions. Small amounts of acidity can be neutralized a t or near the water source with a suitable alkali such a s soda ash. Carbon dioxide Most natural water supplies contain dissolved carbon dioxide. Carbon dioxide comes from a number of sources such a s the atmosphere, decaying organic matter, a n d underground sources. While dissolved carbon dioxide is corrosive in itself, it also accelerates the corrosive action of dissolved oxygen and reduces alkalinity of water. Water with little or no alkalinity can become acidic from dissolved carbon dioxide. Color Deep well and spring waters are usually colorless. Occasionally, water from

shallow wells will contain significant amounts of color. Color is very common in surface water and is usually caused by organic compounds from decaying plant and animal matter. Colored water will discolor all textile products if used for laundering. Colored matter is usually removed by coagulation, settling, and filtering -the normal function of municipal water treatment plants. Organic growihs Any water supply t h a t has been exposed to the atmosphere before use can be expected to contain organic growths, mainly algae and bacteria (both pathogenic and nonpathogenic), that cause clogging, slimy deposits, color, bad taste, and odors. They may also constitute a health hazard. Bacteria growths are usually controlled by chlorination, while algae growth is reduced by storing the water in covered tanks. owgen Oxygen, which is present in all water, is chemically very active and, therefore, corrosive. This corrosive action is particularly apparent in water heaters and hot water lines, leading to iron in the water system and, eventually, equipment and plumbing replacement. Processing water can be treated with oxygen scavengers such a s sodium sulfite to counteract this corrosion. Suspended matter Suspended matter is rarely found in ground water because water is naturally filtered a s it seeps from the surface to the water table. However, following heavy rains, shallow wells may contain suspended matter because rapid seepage rates allow for little filtration. Suspended matter is very common in surface water - the calmer the water, the less suspended matter present. For example, a lake may have very little suspended matter on a calm day; however, high winds can greatly increase the amount of suspended matter. The amount of suspended matter in rapidly moving rivers is usually very high. Suspended matter can be classified into two categories: 1. sediment, consisting of large particles that rapidly settle out in calm water; and 2. turbidity, consisting of small particles that may remain suspended for several days even in calm water. Frequently, both types are referred to a s turbidity. Turbidity is the more difficult to remove, and sediment is removed in all processes that remove turbidity. Turbidity is removed by coagulation - adding chemicals to make the small particles floc to sediment-sized particles-followed by settling and filtration.

WATER SOFTENING F O R LAUNDERING The dissolved minerals in water are responsible for hardness. A relatively small amount of hardness won't interfere with good laundering, but most laundries soften water having more than two grains per gallon (34.2 ppm) of hardness. The water in most sections of the country, however, has a high degree of hardness. Unless hardness is removed or reduced to a minimum, the water will

produce poor quality textiles coupled with poor economy, regardless of the type of surfactant used. The chemicals responsible for water hardness are calcium and magnesium salts and other less abundant alkaline elements. They're troublesome because they form insoluble compounds with soaps or reduce the effectiveness of synthetic detergents. The insoluble soaps formed tend to trap soil particles in the fabric, causing grayness. Also, they tend to oxidize, causing rancid odors on fabrics. Some types of water hardness cause scale in boilers, water heaters, and pipes, resultingin poor efficiency, increased maintenance and repair costs, and excessive fuel consumption. Free fatty acids contained in body soil or certain other fatty soils can react with water hardness, making these soils less soluble and more difficult to remove. Some clay soils exchange sodium ions for hardness ions in hard water, making the clay much more difficult to remove. Several types of chemical water treatments are used in reducing water hardness. The most important methods are described below. Lime-soda treatment This method, used in community water treatment plants, involves adding calcium hydroxide and sodium carbonate to the water, and then allowing the insoluble material formed to settle out. This treatment method doesn't lower hardness sufficiently for laundry use and works only where enormous quantities of partially softened water exist, such a s in a municipal water treatment plant. The treatment does help laundry operators somewhat, however, because it decreases the amount of hardness they have to contend with. Phosphate treatment This treatment involves adding some of the commonly available complex phosphates, such a s sodium hexametaphosphate, sodium tripolyphosphate, or tetrasodium pyrophosphate, to the wash load. However, phosphate use is restricted or banned in some areas. These phosphates may be a n ingredient in formulated soaps or detergents. They tie up or "sequester" the calcium and magnesium ions in such a way that the ions are not available to react, rendering the hardness components incapable of forming insoluble compounds with or "precipitating" soap. Complex phosphates frequently are used in washing formulas a s an aid to the rinse baths. Adding complex phosphates to the bleach or first rinse helps strip the soap from the textiles and regenerates insoluble soaps t h a t may have accumulated in prior laundering. Complex phosphates also can be used in the first flush bath in diaper laundering. These compounds, acting a s separating agents, prevent formation of lime soaps in the diapers during the suds baths. Lime soaps are likely to form because fecal matter is very rich in calcium salts. Chelate treatment Chelates are chemical compounds that tie up hardness components, rendering them incapable of precipitating soap. Chelates may also be used with other

metallic ions, such a s iron, and are frequently used in textile mill operations a s separating agents. Demineralization This method depends on removing mineral salts from water by special synthetic organic resins, simultaneously using two ion-exchange reactions. One reaction removes positively charged cations, such a s calcium, magnesium, and sodium; while another removes negative anions, such a s sulfate, bicarbonate, and chloride. Often demineralized water h a s a mineral content equal to distilled water produced from the same source. Distillation is widely accepted by industries needing water with a very low content of dissolved solids, but laundries don't need such pure water and can't justify the higher costs. Baseion exchange (zeolite or resin) This method is based on the absorption of hardness components, such a s calcium and magnesium ions, by certain natural minerals or by synthetic resins, leaving the effluent water free of hardness. Since this treatment is widely used for laundry purposes, i t is the only method of water softening t h a t will be discussed in detail. The base exchange process softens water by exchanging the sodium ions of certain natural greensands (glauconite) or synthetic mineral resins with the calcium and magnesium hardness in water. Synthetic resins are used widely because they have excellent softening capacity and are longer lasting. Ion exchange resins are available in a number of forms - natural zeolites, synthetic gel-types, carbonaceous minerals manufactured from coal, and synthetic resins produced by copolymerization of styrene with divinylbenzene. Nearly all of the cation exchangers sold today are of this last type.

The useful softening capacity of the resin is expressed in kilograins of hardness per cubic foot of resin (kgr). This capacity depends on the amount of salt used for regeneration and may vary from 20 to 30 kgr per cubic foot. Salt dosage usually ranges from 5.5 to 15 or more pounds per cubic foot of resin. Table 2-1 shows the minimum hardness obtainable a s a function of raw water hardness and salt dosage. The figures in Table 2-1 are based on single-stage softeners. Improved results can be obtained by using two softeners in series. Table 2-1 and Equation 2-1 provide a simple description of the base-ion exchange bath process. Table 2-1 illustrates the softening cycle, and Equation 2-1 shows how the resin radical is represented a s Re. As the hardness cations in the water exchange places with the sodium cations in the resin material, the elements causing hardness (calcium and magnesium) are taken from the water into the resin bed. Resin material h a s a specific capacity for exchanging ions with the calcium or magnesium in the hard water. When this capacity has been reached, the material is said to be exhausted; i t no longer h a s the ability to remove hardness ingredients in the water supply. Before it's completely exhausted, the resin material should be restored to its original form a s follows: 1. Backwash the resin bed a s illustrated in Figure 2-2. This is done by passing a vigorous current of water upwards through the softener. This procedure loosens and regrades the resin bed, holds it in a semi-suspended condition, a n d removes any dirt t h a t collected on top of the resin bed during the softeni n g part of the bath. Make sure the water pressureisn't too high or channels will form t h a t allow the water to pass through without cleaning the resin bed. Figure 2-1: Base-ion exchange (zeolite or resin)

@ Q -

Table 2-1: Degree to which water can be softened - minimum hardness attainable, ppm as CaCO, (Courtesy of Permutit Co.,Inc.) Total cation content of influent

Salt

Ib./cu.fl.

200

400

Softening cycle

- ppm as CaCO,

800

&coming

1200

hard water D~rt

Equation 2-4 Na,Re resin

+

Ca*'or Mg'. hardness

-

Compacted zeolite

CaRe or MgRe spent resin

+

2Nai sodium cations

-.. . ..

. ... Outgoing soft water wrth sodium ions

Figure 2-2: Backwashing of base-ion exchange water softener cycle

&??+++-0utgolng

dirty water

2. Brine the exhausted resin a s illustrated in Figure 2-3. This is done by introducing a predetermined amount of concentrated sodium chloride (salt or brine) solution into the softener. The concentrated salt solution is distributed over the top of the bed and passes through it. The salt reacts with the resin, removing the calcium and magnesium in the form of soluble chlorides, and restoring the resin to its original active or sodium condition. The regeneration process is shown in Equation 2-2. 3. Rinse the resin bed to remove the released calcium and magnesium salts as well a s the residue of unused sodium chloride solution. After these salts have been rinsed out, return the softener to service. Equation 2-2

Bound hardness

CaRe or MgRe spent resin

Zeolite loosened

-coming

backwash water

Figure 2-3: Regenerationof resin (zeolite) with brine

r

addition

/

. . .. . . .. ' . . . . - . 4. 00 . . ' .- 0 . ...- ..... .. 90:

.

.. 0

.

'. 0 .. . .

Zeolite loosened and regraded

'.O

. ..

.

.

a

.

. ,, F: . . .. . .. . . .

Incoming brine with sodium ions

0

. a

.

Available sodium ions

.

b

Outgoing very hard water

+

2NaCI sodium chloride (saw

-

Na,Re

regenerated resin

+

CaCI,

or MgCI, soluble salts

WASHING CHEMICALS

3

S

everal different chemicals are used in washing or sudsing. These chemicals may be added a s separate ingredients or a s a formulated combination. In proper chemical terms, d e t e r g e n t s are a subclass of chemical compounds known broadly as s u r f a c e - a c t i v e a g e n t s or s u r f a c t a n t s . All detergents are surface-active agents, but not all surfactants are detergents. In the laundry industry the term "detergent" is usually used incorrectly to describe a manufactured product containing a surfactant and possibly other additives to aid in cleaning. Very simply, detergency involves removing foreign substances (soil*) from any surface. In laundering, the detergent function involves removing soil from textile fibers. This chapter describes how surfactants and additives remove soil from textiles.

SURFACTANTS While some soils can be removed from fiber surfaces with mechanical action and water alone, most can't be. This is where surfactants play a role. The process of soil removal involves loosening and lifting soils from a fiber's surface and holding these soils in suspension until they can be removed by dilution. All laundering baths are a form of dilution. The main function of a surfactant or surface-active agent is to s u s p e n d soil, although it also plays a key role in loosening soil. In addition, surfactants act a s w e t t i n g a g e n t s . Reducing water's surface tension enhances its ability to penetrate the textile fibers. How surfactants work As the name implies, surfactants work a t all exposed surfaces in the washing zone -the solution surface, fiber surfaces, and interior surfaces of the washing machine. -

*In this chapter, the term "soi1"refers to the normal insoluble soils that can be removed using conventional wash formulas. Soil that can't be removed and discolors the fabric is referred to a s a "stain."Stains aregenerally removed b y bleaching, which is covered in Chapter 4.

Every surfactant molecule is made up of two parts, a s shown in Figure 3-1. One part - drawn a s a rectangular tail in Figure 3-1 -is hydrophobic (water hating), also called oleophilic (oil loving). The other part - drawn a s a circular head in Figure3-1 -is hydrophilic (water loving), also oleophobic (oil hating).

loving) part of many surfactant molecules plus molecules of oil. The exterior is made up of the hydrophilic (water-loving) part of the surfactant molecules, which allows the oil to disperse into the water. Figure 33: Oily surfactant complex

Figure 3-1: Surfactant molecule schematic

Surfactants do their main job of suspending soils a s follows. Without agitation, oil and water mixtures usually separate into two liquid layers with the oil normally on top. When a surfactant is added to this two-layer system, the hydrophylic or water-loving portion of the surfactant molecule tries to enter the water, while the hydrophobic or water-hating part of the surfactant molecule tries to move away from the water and attach to the oil, a s shown in Figure 3-2. Figure 32: Orientation of surfactants in oil and water

The other main job of surfactants is to loosen soil from fibers. Mechanical action alone, represented by the tumbling action of a washing cylinder, can't loosen all soil particles from fiber surfaces because the particles often are surrounded by a film of grease or oil. This film repels water and imprisons the particles on the fiber's surface (see Figure 3-4). Figure 3-4: Dirt and oil imprisoned in $extile

Oil

Water

Moderate agitation will then disperse the oil into the water a s small globules surrounded by surfactant molecules, a s shown in Figure 3-3. The interior of these oil/surfactant formations contains the hydrophobic (water-hatingor oil-

To free these trapped particles so they can be removed, surfactants penetrate the oil or grease film. Surfactant molecules a t the oil/water interface surrounding the soil particle lower the tension or force separating the oil from the water, allowing mechanical action to lift the soil particle from the fiber surface, a s shown in Figure 3-7.

Figure 3-7: Oily soil lifted from textile

Figure 3-5: Surfactant penetrating oily soil

Figure 36:Surfactant dispersing oily soil

When the soil particle is free from the fiber, it moves through the washing solution, where it is affected by gravity and turbulence. Free soil particles tend to attract each other, causing them to draw together or agglomerate. This makes them larger and more susceptible to gravity forces, which could make them redeposit on the fabric. It's here that the surfactant's soil suspension properties become important. After mechanical action frees soil from the fiber, surfactant molecules hold it in suspension in the washing solution, a s shown in Figure 3-3. SoiVsurfactant formations such a s the one shown in Figure 3-3are limited in size by the nature of the hydrophilic part of the surfactant. The formations are small enough to remain in suspension until removed from the water by the dilution effect of each successive bath in the washing/rinsing process. Surfactant classifications Surfactants are organic chemicals t h a t contain a s their principal parts the elements carbon a n d hydrogen, along with oxygen a n d nitrogen, and minor amounts of sulfur. Surfactants are classified based on how they ionize in solution; t h a t is, how the active portion of a surfactant molecule is charged: cationic - the active portion i s a cation or a charge; R anionic - the active portion is a n anion or - charge; and nonionic - the active portion isn't electrically charged, meaning no ionization. Cationic surfactants are usually ammonia derivatives (nitrogen compounds) t h a t are rarely used a s surfactants for cleaning. However, they provide the basis for many fabric softeners a n d antibacterials. Cationic surfactants are discussed in more detail in Chapter 5.

+

-

-

Anionic surfactants historically have been themost widely used surfactants for cleansing; however, nonionic surfactants are the most widely used today. Both of these classes of surfactants are discussed below and a summary of this information is presented in Table 3-1. Table 3-1: Comparison of surfactant types Anionic

Nonlonic

Solubility

Increases with temperature

Decreases with temperature

Sudsing

Voluminous

Low to medium

Suds stability

Good to excellent

Poor to good

Detergency Particulate soils Oily soils

Excellent Good

Fair Excellent

Emulsifying

Fair to very good

Excellent

Soil suspension

Fair to good

Fair

Softening

Poor to good

Excellent Very good

Bacteriostatic Antistatic

Calionlc

Fair to excellent

Very good

Anionic surfactants

-P Soap is a natural surfactant t h a t is produced by mixing animal fats (tallow) or vegetable fats with caustic soda or caustic potash. The use of tallow soap spans some 25 centuries. To this day, soap remains a n important surfactant in the laundering industry. Sodium stearate, represented in Figure 3-8, is a common soap used. Figure 3-8: Soap (sodium stearate)

As a surfactant, soap performs very well in soft water. Its good suspending capability produces excellent whiteness in cotton textiles. Also, soap has a built-in cost-control feature. If too much is used. suds overflow the machine. Soap has some drawbacks, limiting its use. Acid soils, in the absence of added alkali, convert soap to a fatty acid. This insoluble, gelatinous material has no detergent value. It can also trap soil on fabric surfaces, causing graying. Consequently, soap must be protected by a sufficiently alkaline wash bath. The detergent action of soap is also reduced or destroyed by hardness in the water supply and/or in the soil being removed. Hardness forms insoluble lime soaps - gelatinous masses that trap soil on the fabric and cause graying a s well as odors.

Synthetic anionic surfactants At the close of World War 11, synthetic anionic surfactants came into general use because most home laundries lacked water-softening equipment. They immediately topped the list of detergents used in the U S . Anionic synthetic detergents are similar to soap in that they are high sudsing and excellent wetting agents and can often overcome some of the drawbacks of soap. S u l f a t e d f a t t y alcohols. Sulfated fatty alcohols were among the first widely used syntheticsurfactants. They aremade by reducingfatty acids to the corresponding alcohols, followed by sulfation and neutralization. Sulfated fatty alcohols are excellent surfactants, high sudsing, but poor lime soap dispersers. Sulfonated amides. This is a very important class of surfactants formed by the reaction of the acid chloride of a fatty acid with an amine. These surfactants are chemically outstanding in acid stability and are very stable in alkaline solutions and in the presence of bleach. They are also good lime soap dispersers. In addition, sulfonated amides are effective in the presence of salt and are used in seawater detergents. A l k y l a r y l s u l f o n a t e s o r a l k y l b e n z e n e sulfonates. These are very good surfactants. They were first known a s the "keryl" benzene sulfonates because they're made from kerosene in reaction with alkylbenzene, followed by sulfonation. Comparing detergency capabilities, alkylbenzene sulfonates are a s effective a s sulfated fatty alcohols and only slightly less effective than soap. These compounds are stable in acid and alkaline solution and in the presence of bleach. Once called ABS compounds - for sodium alkylbenzene sulfonate - they are now referred to a s U S , linear alkylate sulfonate. Chemically, the compounds have the same composition, but U S has a straight, unbranched alkyl chain, where ABS has a highly branched alkyl group. This change was made in the mid-1960s to improve biodegradability. LAS biodegrades very rapidly while ABS does so much more slowly. Detergency performance of both products is the same. Sulfated nonionics. Ethylene oxide condensate-type nonionics, which are discussed in the next section, are excellent surfactants, but they produce unstable foams and often cause turbidity in the cleaning solution. To increase foaming power and solubility, nonionics are often sulfated. This sulfation followed by neutralization converts these compounds into anionic surfactants. Often sulfation is limited, producing a compound that's a mixture of nonionic (the nonsulfated molecule) and anionic (the sulfated molecule) surfactants. Nonlonic surfactants

This class of surfactants differs from anionics and cationics in that no ions are produced in solution. Widely used, nonionic surfactants are excellent emulsifiers of oil soils, better generally than soap and the anionic detergents. Another plus is the tendency of nonionics to be attracted to and coat polyester fibers, which tends to shield the fibers from soil and dye particles. This is an important benefit in the light of polyester's scavenger nature. A drawback of nonio-

nics is that they don't have the soil-suspendingpower of anionic synthetic surfactants and soap. The classes of nonionic surfactants important to the laundering industry follow. T h e condensate of e t h y l e n e oxide o r propylene oxide w i t h a f a t t y alcohol. The structure of this type of compound made with ethylene oxide is shown in Figure 3-9.The value "n" in Figure 3-9is the number of times the formula unit is repeated. In general, optimum detergency occurs with "n" in the range of 7 to 15. However, some molecules with large Rs (long fatty chains have "n" values greater than 20, making them excellent surfacsuch as CIBHs7) tants but less biodegradable than other types. These compounds are widely used in proprietary products, frequently in combination with other surfactants. Figure 3-9: Nonionic, condensate of ethylene oxide with a fath/ alcohol R(-0-CH2

-CHll),-0

-H

F a t t y acid condensates w i t h e t h y l e n e oxide. These compounds also can be made by the esterification of a polyethylene glycol with a fatty acid. In acidic solution, these surfactants break down to form fatty acids (a reaction similar to that of soap). In highly alkaline solutions, they break down to form soaps and are no better than the corresponding soap used by itself. C o n d e n s a t e of e t h y l e n e oxide w i t h a n a m i n e o r amide. These surfactants are nonionic in neutral and alkaline solutions but can exhibit cationic behavior in acid solutions. C o n d e n s a t e of a l k y l p h e n o l s w i t h e t h y l e n e oxide. This is a high-foaming nonionic surfactant that is stable in acid and alkaline solutions and has excellent hard-water resistance. The structure of this class of compounds is shown in Figure 3-10. Figure 3-40:Nonionic, condensate of alkyl phenols with ethylepe oxide

-

0

(-0-CH2-CH2)n-0-H

I

Often called ethylene oxide adducts of alkyl phenol, this is the most important single class of surfactant in the laundry. General laundry use is when the "n" value equals 9 or 10 and temperatures range from 100' to 180°F.

ALKALIES While soaps and synthetic surfactants are organic chemicals, alkalies, in contrast, are inorganic chemicals derived almost entirely from the earth's crust. Alkalies and alkaline salts are added to surfactants to assist in soil removal and soil suspension. For this reason, they are frequently referred to as builders or alkaline builders. Textile detergency is most effective in an alkaline medium rather than acid. While some detergent processes use an acid medium, practically speaking, textile cleaning normally occurs in an alkaline medium. This statement is especially true for tallow soap. Tallow soap (produced by

combining animal fat and alkali) reverts to a fatty acid and loses its detergent properties unless it's used i n a n alkaline medium. The same problem can occur with synthetic detergents, especially in a heavy-soil formula. Alkali chemistry

Broadly speaking, an alkali is a substance that neutralizes an acid. Elementary chemistry textbooks define it a s a compound that, in water solution, furnishes hydroxide (OH-) ions. A solution is alkaline if its pH measures 7.1 and above. Two other tests: Litmus paper turns from red to blue and methyl orange indicator turns orange if a solution is alkaline. The most common alkalies are sodium hydroxide (NaOH), potassium hydroxide (KOH),and ammonium hydroxide (NH,OH). All of these substances produce hydroxide anions in soIution, as shown in Equation 3-1. Equation 3-f NaOH

____+

sodium hydroxide

+

No+

OH-

sodium ion

hydroxide ion

In laundering, alkalies are used to neutralize acids forming water and a salt. Equation 3-2 illustrates this process. Equation 3-2 sodium hydroxide

hydr~chloric acid

sodium chloride (salt)

water

Salts formed when an acid is neutralized by an alkali may be neutral, acid, o r alkaline in nature a s illustrated below: A salt formed by the reaction of a strong alkali and a strong acid is neutral a s shown in Equation 3-3. Equation 3-3 NaCl

+

sodium chlon'de (salt)

H20

-+

N ~ +

+

sodium

wafer

CI-

+

ch1oricYe anions

cations

H70 wafer

A salt formed by the reaction of a strong acid and a weak alkali is acid, a s shown in Equation 3-4. Equation 3-4 +

aluminum Chloride (salt)

3H,O water

--b

AI(OH), alumirium hydroxide

+

3H7 acid

+

3Cichlonde

anions

-

A salt formed by the reaction of a weak acid and a strong alkali is alkaline, a s shown in Equation 3-5. Equation 3-5 Na2C03

+

sodium carbonate (salt)

H20 water

2Na'

+

sodium cations

OH-

+

hydroxide anions

HCO;

Equation 3.6 +

sodium metas;licate

H20

-------, 2Na+

water

+

&;urn cations

OH-

+

HSiO; any one of several silcate anions

hydroxide anions

Equation 3-7 Na3mA tisodium phosphate

+

H20 water

------b

3Na' sodium cations

+

H2FQ dihydrogen phosphate anions

Table 3-2: Common alkaline builders

bicorbonde anions

Compounds referred to a s alkalies in the laundering industry usually aren't true alkalies but salts of a weak acid and a strong alkali. In solution, these salts produce the hydroxide anion (OH-), a s shown in Equations 3-5,3-6, and 3-7. Na2Si03

percent for sodium metasilicate pentahydrate. Another good choiceis anhydrous metasilicate, but only where the absence of water provides a concentrated product.

+

20Hhydroxide anions

Table 3-2 lists common alkaline builders used in the laundering industry. This group contains alkalies and alkaline salts. The terms "active" and "inactive" alkali have been used by laundry technologists and operators for many years. Broadly speaking, active alkali is the percentage of total sodium oxide content available a t a pH greater than 8.3. Except for sodium hydroxide, the alkaline silicates appear to have the highest active and total sodium oxide (Na,O) levels a s well as the highest pH values. Both of these factors - pH and sodium oxide content - measure the building strength of a n alkali and reflect the concentration of hydroxide anions (OH-) in solution. The role of sodium oxide content and/or solution pH in a n alkali's ability to build or enhance a detergent is very complex. In general, alkalis are ranked by their percentage of active sodium oxide content, which correlates with their solution pH, as shown in Table 3-2.This measure of alkalinity is often referred to as alkaline pressure. Note the sodium metasilicate and sodium bicarbonate listings in Table 3-2. The total sodium oxide content of sodium bicarbonate a t 36.9 percent is significantly greater than that of sodium metasilicate pentahydrate at 29.2 percent. Yet no experienced laundry operator would choose sodium bicarbonate over sodium metasilicate pentahydrate for laundering items such a s aprons because the active alkalinity of bicarbonate is 0.0 percent compared with 28.2

Percent Na,O

Bullder

Fonnula

Sodium hydroxide (caustic soda)

NaOH

Potassium hydroxide Potassium orthosilicate Sodium orthosilicate (anhydrous) Sodium metasilicate (anhydrous) Sodium orthosilicate (pentahydrate) Sodium metasilicate (pentahydrate) Sodium carbonate (soda ash) Sodium bicarbonate Sodium tripolyphosphate Trisodium phosphate (dodeca

Active' Total*'

Theoretical total

pH d water solulions (%concentrationsas sham)

1.0% 0.5% 0.1%

75.5%

76.0%

77.5%

13.1

129

122

KOH

-

-

55.3

13.1

12.9

12.3

KAsioA

-

-

50.0

13.0

12.7

12.1

NaASio4

59.0

60.8

67.4

13.0

12.7

11.9

Na2Si0,

49.0

50.8

50.8

12.6

12.3

11.6

Na~Sio4.5~~0 440

4.8

45.3

12.9

12.6

11.8

NazSi03.5~~0 28.2

29.2

29.2

12.4

12.0

11.4

Na2C0,

28.7

57.4

57.4

11.3

11.2

10 7

NaHC03

0.0

36.9

36.9

8.4

8.3

8.3

Na3P3010

4.3

16.9

43.0

9.4

9.6

9.9

Na3POp12H20 10.0

18.8

24.1

12.1

11.8

11.0

'Titratable with phenolphthalein "Titratable with methyl orange

The alkaline silicates

Generally, the surfactant is considered the principal agent in soil suspension, but studies show that alkalies help in this role. Alkaline silicates, in particular, have excellent soil-suspendingpower and work hand in hand with surfactants. In addition to helping in soil suspension, alkaline silicates help maintain pH

levels, or buffer a solution. Buffers are ingredients that help a solution maintain a stable pH when acid or alkali is added. True buffers are usually a mixture of a weak acid salt, or a mixtureof a weak alkali and a weak alkali salt. Laundry alkalies are not true buffers, but they do provide some resistance to pH change from added acids a s shown in Figure 311. On the chart, caustic soda and silicated alkalies show strong buffering action; that is, they do not change much in pH a s they're neutralized.

Figure 3-4 4: Bufferingeffect of alkali, solutionsof industrialalkaliescontaining 0.02% Na20(Courtesy of pQ Cop.) . NaOH -- -.- - -- -. (Caustic soda)

(Sodium sesquisilicate) 3 ~20a. . 2 -.~ .~ ..- -.--.Na2Si03- . - .- . - (Sodium metasilicate) Na3pQ

12

I

--- - - --- - -

Na2C03

(Trisodium phosphate) (Sodium carbonate)

The solid silicates Some alkaline silicates are available in dry form a s listed in Table 3-3. Table 33: Solid alkaline silicate ratios Theomtical percent sodium oxlda (total)'

Molecular formula

Name

Sodium metasilicate (pentahydrate)

Na20. SIO,

Sodium orthosilicate (pentahydrate)

2Na20 SIO,

5H20

Sodium metasilicate (anhydrous)

Na,O

Sodium orthosilicate

2Na20 SIO,

5H20

SIO, 67.4'

Theoretical valuesbasedupon anhydroussolid. Thecompletely hydroussolidmay not be stable, and significant amounts of moisture may be present.

As stated before, the level of sodium oxide (Na,O) content is an indication of the building power of the alkali. Equation 3-8 is the chemical breakdown for anhydrous sodium metasilicate: Equation 3-8

--

Na2Si03

--

6

Si02

+

>-

Na20

\

+

+ +

\ \ I

2

Si02

The molecular weight of the sodium oxide unit is (2x23) 16 = 62; for t h e silica unit it's 28 (2X 16) = 60. The proportion of sodium oxide in the anhydrous compound Na,O SiO, is 62/(62 + 60) = 50.8 percent. This is referred to as the total sodium oxide content of sodium metasilicate. In the pentahydrate, the total sodium oxide content is 62/[(62 60 (5 X 18)] = 29.2 percent. While sodium nietasilicate has a one-to-oneratio of sodium oxide to silica, sodium orthosilicate has a two-to-oneratio of sodium oxide to silica. The total sodium oxide content of sodium orthosilicate(2 X 62)/[(2 X 62) 601is 67.4 percent. As Equation 3-9 indicates, sodium orthosilicate is manufactured by mechanically combining proportionate amounts of caustic soda with sodium metasilicate.

+

-:-=

\

I

Na20

3

ML N/5 HCL PER I00 ML

Caustic soda is also an active builder for soap or synthetic detergent if properly handled and controlled in the washer. Prior to about 1950, many plants used straight caustic soda, but this practice has completely disappeared because: Caustic soda is hazardous to handle. Caustic soda is concentrated and difficult to control i n the laundering process. It's easy to over or under use. To offset these problems but maintain the benefits of caustic soda, chemical companies combine i t with silicates, carbonates, and to a lesser extent, phosphates and alkaline silicates. Silicates are available in either liquid or powdered form. Each has its uses, a s described on the following pages.

+

Equation 3-9 Na2Si03 sodium metasilicate

+

2NaOH (Na20+ H20) caustic soda

>--

2Na20. Si02 sodium metasilicate

+

H20 water

The finished compound, though called anhydrous in the trade, actually contains moisture. Taking this into account, the total sodium oxide content of

commercial sodium orthosilicate is not 67.4 percent but about 60.5 percent. Although i t would seem that all silicated alkalies should produce the same results as long a s the break and subsequent baths achieve proper alkalinity, there's reason to believe that all alkalies don't perform alike. For some time, operators have used orthosilicate for linen supply operations and metasilicate for industrial laundering. Linen supply processing generally involves oily soils of animal and vegetable fat. These soils are best removed by the strong saponification action of the active sodium oxide portion of an alkali. Therefore, a n alkali with a relatively high proportion of active sodium oxide such as orthosilicate is needed. For the mineral oil-based soils found on industrial uniforms, shop towels, and similiar classifications, the better emulsifying action of metasilicate plays a significant role in soil removal. For example, studies indicate that shop towels laundered with metasilicate show greater absorbency and less redeposition than those laundered with orthosilicate when both alkalies are added to an equal titration level. The liquid silicates

The alkaline silicates listed in Table 3-3 can be made in the laundry plant by combining liquid causticsoda with liquid silicate. Liquid caustic soda X 50percent by weight is a common item, as is liquid silicate. Liquid silicate comes in many forms. The type used in laundries, 8.9 percent Na,O and 28.7 percent SiO,, is known as 1:3.22 (the ratio of Na,O to SiOJ. Liquid caustic soda and silicate can be purchased in tanker quantities and stored. They then can be combined in the proper proportions to produce the aforementioned silicates or, for that matter, any other molecular ratio required. For example, 7.2 gallons of liquid caustic combined with 14.7 gallons of liquid silicate and enough water to bring the volume up to 100 gallons produces identically the same mixture as one 100-pound bag of anhydrous sodium metasilicate added to a 100-gallon tank of water. While the mixtureis identical, the cost isn't. Orthosilicate made by combining 11.6 gallons of liquid caustic with 9.7 gallons of liquid silicate, a practice followed by many plants, is about 45 to 50 percent below the cost of bagged alkali. Commercially available potassium orthosilicate is a highly concentrated liquid silicate. Potassium salts are alwaysmore soluble than sodium salts and prices range from the same to about 1.7 times as much as their sodium counterparts. Potassium orthosilicate is a very effective alkaline builder. Potassium silicates can be prepared in water solutions a s concentrated a s 4.2 pounds per gallon. Potassium silicate solutions are far more resistant to freezing than sodium silicate solutions of the same strength. For this reason, potassium orthosilicate solutions can be transported, stored, and used a t higher concentrations than can sodium orthosilicate solutions. In order to achieve equal results from potassium- and sodium-based alkalies, 1.1to 1.5 times (depending on Na,O to SiO, ratio) a s much potassium silicate as sodium silicate must be used. This produces a solution with equal alkalinity and SiO, amounts.

Alkaline damage to fabrics

Washing with alkaline builders declined in the 1980s because of a decrease in cotton fabrics and a n increase in polyester fabrics. Cotton is more resistant to damage from strong alkaline solutions. In fact, cotton fabric strength is often increased by alkaline solutions. For maximum soil removal, strong alkaline detergent solutions are usually used to launder cottons. Polyester, on the other hand, can be damaged in strong alkaline solutions. The fiber surface becomes pitted and/or the fabric loses strength - a chemical process termed alkaline hydrolysis. All the conditions that lead to alkaline hydrolysis haven't been firmly established, but a combination of higher pH and temperature causes the greatest damage and, in some cases, can destroy the polyester fiber. Quaternary ammonium surfactants (quats), which are used to formulate many types of fabric softeners, dramatically increase the severity of alkaline hydrolysis. Some manufacturers of polyester fabric recommend not using quarternary ammonium fabric softeners on their fabrics. In addition, polyester's resistance to alkaline hydrolysis depends on the type of polyester and the treatments the fibers may have received during manufacturing. The best practice is to avoid pH values above pH 11 and temperatures above 160°F. Many detergent manufacturers offer formulated detergents that produce only moderately alkaline solutions. These detergents provide excellent surfactant action to make up for the work done by alkaline builders in more traditional detergent formulations. Phosphates

Phosphorous forms many compounds with sodium and oxygen, all of which are alkaline. These alkaline salts are very useful in laundering and other cleaning procedures, but many areas of the U.S.have banned or restricted phosphate use, resulting in lower levels of soil removal and fabric whiteness. The complex phosphates - including sodium tripolyphosphate ("tripoly") (Na,P,O,,J, tetrasodium pyrophosphate, and sodium hexametaphosphate are used most frequently as builders for industrial and consumer laundry detergents. Phosphates sequester the hardness in water, leaving the detergent free t o remove and suspend soil. They render calcium and magnesium ions incapable of forming insoluble soaps, but don't precipitate these hardness elements. T h e advantage of this sequestering action is that soil can't be occluded or trapped in the fabric by precipitates if no precipitates are formed. So the whiteness of whites and the brightness of colors are preserved. Sodium tripolyphosphate also sequesters a large number of metallic ions. For many years, plants using tallow soap have added complex phosphates i n the bleach bath to regenerate soluble soap from its precipitated form. This enhances the whiteness and brightness of the finished product. Even relatively small amounts of precipitated soap that have become lodged in fabrics because of minute amounts (1 to 10 ppm) of water hardness in softened water can b e regenerated by adding small amounts of complex phosphate.

Complex phosphate use is certainly not limited to soap formulas; it also enhances the performance of synthetic detergents, suspending soil and helping to preserve the whiteness of white and the brightness of colors. On an equal-weight basis, the most effective phosphate is sodium hexametaphosphate, and trisodium phosphate is the least effective. Trisodium phosphate (Na,PO,) is a simple phosphate in the form of an alkaline salt. Its pH is 11.8(at a 0.1 percent concentration), and total sodium oxide content is 24.1 percent. Although its structure suggests it could function as a detergent builder, its low available sodium oxide content excludes it from general use. Trisodium phosphate, technically sodium orthophosphate, softens water by precipitating the calcium and magnesium ions in the form of calcium and magnesium phosphate. In this respect, it resembles sodium carbonate. Trisodium phosphate is widely used in non-textile applications where its mild alkalinity provides a wide spectrum of soil- and stain-removal action. Phosphate-freesequestering agents

Organic sequestering agents have replaced phosphates in certain parts of the country where phos'phate use h a s been restricted. These materials aren't a s effective a s phosphates, but they're stronger sequestering agents for a wider range of substances. Some of these organic compounds are derived from the sodium salts of ethylenediaminetetraacetic acid (EDTA). These phosphate-free compounds are very stable under all conditions. Some EDTA derivatives maintain their structure and sequestering power under extreme conditions of heat and alkalinity, conditions that cause complex phosphates to revert to the basic trisodium phosphate and lose sequestering power. They are also quite effective in sequestering soluble iron. A number of these compounds, sometimes referred to a s chelating agents, have similar chemical structures. While chelating agents are very efficient sequestering agents, their main function in the laundry is to control impurities such a s iron and manganese, which cause problems in very low concentrations. EDTAs can sequester (or chelate) iron in almost any concentration. The specific EDTA compound selected to do the job depends on the pH of the application - for example, the EDTA best suited for pretreating incoming water is different from the one best suited for the sour bath. Consult suppliers for information on the proper concentration of these sequestering agents, since the amounts needed depend on the concentration of the contaminant.

OTHER WASHING CHEMICALS Surfactants, alkalies, and phosphates constitute the bulk of chemicals used in the washing process. Other chemicals may be used in small amounts to increase quality. Optical brighteners

Cotton, in its natural state, is cream white to beige. Even after bleaching, cotton tends to revert to its natural color. Moreover, cottons can turn yellow during

ironing if bicarbonates haven't been properly removed in rinsing or neutralized by souring. The yellowing is caused by the action of carbonates formed when the bicarbonates begin to decompose. Optical brighteners, also known a s fluorescent whitening agents, are essentially colorless dyes that, when applied to textiles, papers, plastics, and other substances, absorb ultraviolet radiation and emit light of various hues. Blue i s the preferred hue for white textiles becauseit complements or counterbalances the yellow tint already present in off-white substances, imparting a greater apparent whiteness to the materials treated. Manufacturers add brighteners to practically all proprietary washroom supplies to gain a marketing advantage. Certain brighteners can produce significantly brighter finished textiles than might ordinarily be the case, even after a single wash, if added in sufficient quantities. Brighteners generally are absorbed only by cellulosic fibers, such a s cotton. A few respond to nylon, while others are absorbed by wool and acetates. Currently, no brighteners have an affinity for polyester fibers, so most producers of polyester fiber incorporate brighteners within the fiber during manufacturing. A brightener's effect is decreased as the fiber ages, which explains w h y laundered fabrics differ so markedly in whiteness. This is particularly evident when all-cotton items such a s bath towels are compared with sheets and pillowcases that may have been washed in the same load. The bath towel fibers. generally all-cotton, have a far greater capacity to absorb brighteners in t h e washing process than the fibers of the sheets and pillowcases, which generally are 50/50 polyester/cotton. Operators who purchase generic or raw chemicals can get the benefits of a brightener by adding one proprietary chemical to the generic mix, by making a stock solution of a water-soluble brightener, or by including a water-soluble brightener in the stock solution of one of the other washroom supplies. The correct point in the wash process to add a brightener is determined by t h e solubility and bleach resistance of the brightener. Most brighteners are best absorbed in a high-temperature surfactant bath. Therefore, manufacturers commonly add brighteners to detergent formulations. The effectiveness of some types of brighteners is reduced by bleach. To avoid this problem, certain warm- and cold-water-solublebrighteners c a n be used in a sour bath, protecting the chemical structure of the brightener from bleach used earlier in the formula. Carboxymethylcellulose (CMC)

Soap or synthetic detergent's job in thelaundering process is to wet, penetrate, deflocculate, and suspend soil. Tallow soap used in soft water can perform a l l four functions well. Synthetic detergents alone don't suspend soil a s well as soap does. Early research on soil-suspending products found that certain colloidal substances, notably sodium carboxymethylcellulose (CMC), a versatile cellulose derivative, have the unique ability to enhance the soil-suspending power of a l l synthetic detergents. As a result, CMC is widely used as an additive in most laundry detergents containing anionic and nonionic surfactants. Modern laundry detergents are complex mixtures of many substances for-

mulated to provide balanced washing action. By adding from 0.5 to 1.5percent of CMC to the detergent, synthetic formulations gain soil-suspending power about equal to tallow soap. CMC alternatives include various long-chain polymers such as the polyacrylates. Proprietary products

Some proprietary alkalies combine caustic soda with soda ash in formulations balanced to provide the same alkaline pressure (sodium oxide content) as the alkaline silicates. These products may also combine phosphates and other chemical specialties for a wide spectrum of building performance. Many laundries use proprietary built soaps and syntheticdetergents instead of buying basic supplies. These products are compounded using all the ingredients necessary for laundering a wide variety of classifications. Considerable research time and money have been spent to develop these formulas, so manufacturers often protect them by patents. These proprietary products usually consist of the following: a surfactant or surfactants, an alkali or a blend of alkalies, water softeners, suds stabilizers, soil-suspending agents, and brighteners. The more alkaline products range in pH from pH 11.5to 12.5 and have active/ total alkalinity ratios that compare favorably to metasilicate and orthosilicate. These products rely on alkaline chemistry to break down and remove soils from the textiles. The less alkaline products range in pH from pH 9.5 to 11.0and are especially suited for polyester fabrics to avoid alkaline damage. These products use the most current surfactant technology to emulsify and remove soil and may consist of a blend of several surfactants. They perform on a comparable level with the more alkaline products. Low-alkaline products generally cost more than high-alkaline products, but the costs may be offset by prolonged fabric life, color retention, and/or reduced water and energy consumption.

B

leach has three roles in the laundering process: removing stains, sterilizing linens, and maintaining whiteness. Of the three roles, bleach is most effective in removing stains and killing bacteria and other microorganisms. It does have a whitening effect on cotton, but whiteness retention is best accomplished by proper washing procedures. The whitening action of bleach is simply a fortunate byproduct. This chapter discusses the reasons and methods for using bleach. STAlN REMOVAL Most soils encountered in a laundry can be removed by a good, bleach-free washing formula. Bleach has no place in general soil removal because it doesn't effectively remove inert dirt that's been bound onto fabric by animal and vegetable fats or mineral oils. In fact, bleach only removes inert soil when it's used in such high concentrations and temperatures and a t such unfavorable pH conditions that it completely removes the surface of cotton fibers and severely reduces textile strength (see Table4-1).Even under those conditions, the small amount of soil removed is probably the result of mechanical action and the bleach's alkali content. Table 4-1: Effect of chlorine bleach on general soil removal (Soil removal measured on cotton standard soil cloth produced at Texas Woman's University) Bleach strength (%Cln)

1.O 1.O

Concentrdon (quartsper 100 pounds) pprn

2 8

100 400

Ternpercrhrre (OF)

PH

120 160

9.6 7.5

Strength loss

Soil removal

3.9 100.0'

7.9 7.4

'Strength of bleached sample was too small to measure.

Sometimes, however, small amounts of certain tenacious soils remain in the fabric. These soils are classified a s stains and are most often caused by certain

foods, mildew, some medicines, and dyes. Bleaching is the most effective and economical way to remove these stains.

BLEACH TYPES AND HOW THEY REMOVE STAINS There are two types of bleaches: oxidizing and reducing. Both types eliminate stains by removing the stain's color, making it invisible, or solubilizing the stain so it can be rinsed away. However, the two types of bleaches operate by opposite methods. Oxidizing bleaches take electrons from the stain, while reducing bleaches add electrons to the stain. Oxidizable stains, which include organic substances, far outnumber reducible stains, which include dyes and metals. Oxidizing bleaches include: I chlorine bleach, I hydrogen peroxide, I sodium perborate, I sodium percarbonate, I sodium peroxide, a n d I potassium permanganate. Reducing bleaches include: I sodium hydrosulfite, sodium bisulfite, I titanous chloride (stripping salt), Isodium thiosulfate, and oxalic acid. Of all the bleaches, chlorine is the most commonly used in the laundry.

STERILIZING WITH BLEACH Bleaches destroy bacteria and other microorganisms even when they're used under less than ideal laundering conditions. Of all the bleaches, chlorine bleach is the most effective sterilizing agent available to the launderer. As much a s 99.8 percent of the viable microorganisms in soiled textiles are eliminated by a s little a s 25 ppm of chlorine (one pint of one percent bleach per 100 pounds of fabric). Four other factors help kill or remove microorganisms from textiles during laundering: 1. chemical action-for example, the cauterizing action of alkali; 2. temperature-especially a t 160°F or higher; 3. dilution-from repeated suds and rinse baths; and 4. time-of the wash/rinse process. These four factors cumulatively work to lower total counts of all microorganisms. Textiles are essentially free of microorganisms immediately following processing in any of the bleach-containing laundering formulas listed in Chapter 7. However, microorganisms can again contaminate textiles during extraction and subsequent handling. Methods to deal with recontamination arediscussed in Chapter 5.

HOW CHLORlNE BLEACH AFFECTS TEXTILE STRENGTH LOSS IN COTTON Proper control of bleaching is one of the most important factors in minimizing tensile strength loss in cotton fabrics. Table 4-2 summarizes the relationship between textile strength loss and exposure to chlorine bleach. These figures have been drawn from a large amount of data accumulated over many years of studying the role and action of chlorine bleach in laundering. Table 4-2: Effect of available chlorine solutions on cotton fabric (Conditions: Textles subjected to 50 bleaching treatments; bleach used assayed 1.0percent available chlorine.) Concentration

Quarts

Temperature

per 100 Ibs

ibpm

pH

2

100

9.6

(OF)

80

Fabric sirength loss (%) 0.0

The first and third sets of values in Table 4-2 show the effect of temperature a t two bleach concentrations. The effect of temperature, even a t a moderate bleach level (100 ppm or two quarts of one percent bleach per 100 pounds), is quite pronounced. Strength losses increase from 4.5 to 68 percent a s temperature increases from 120' to 200°F. The effect of pH on fabric strength is also quite dramatic. Lower pH increases chlorine bleach activity.

RECOMMENDED USE OF LIQUID CHLORINE BLEACH Textiles laundered in a formula using no chlorine bleach show tensile strength loss about two percentage points lower than textiles laundered in the same formula with bleach according to conditions recommended in Chapter 7. The type of laundering equipment and the brand of laundry supplies, a s long a s the supplies are of good quality, appear to have little effect on strength loss. Chlorine bleach, when used properly, will not cause a significant increasein the amount of tensile strength loss. However, several factors must be carefully controlled:

Iquantity and concentration of bleach solution, Itemperature of the bleach bath, IpH of the bleach bath, and Itime of the bleach bath.

These four factors must be balanced properly to achieve maximum stain removal with minimal loss of fabric strength. Any change in one factor must be accompanied by compensating changes in one or more of the other factors to maintain comparable stain removal and control fabric strength. When making changes, keep in mind that bleaching activity increases when: Ithe quantity or concentration of the bleach solution increases, Ithe pH is lowered, or Ithe time and temperature of the bleach bath is increased. Each 18°F increase in temperature doubles bleaching activity. Guidelines for using chlorine bleach in processing historically have been based on 100 ppm bleach (two quarts of one percent bleach per 100 pounds of textiles) a t a pH of 10.2 to 10.8 for a period of six to eight minutes a t a temperature between 140' to 160°F. This procedure is widely used in theU.S. a n d i s referred to as bleaching in the clear with no residual soil present. Any residual soil and/or certain other contaminants present in the bleach bath may react with the bleach first and thereby neutralize it. This reduces the concentration of chlorine actually available to remove stains or sterilize textiles. Some laundry operators add additional bleach solution to the bleach bath to compensate for residual soil. The effects of this practice on textile strength have not been firmly established. Overnight soak

An overnight soak is a n effective modification of the historical bleach use guidelines. Bleach is used a t the rate of 400 ppm (eight quarts of one percent bleach per 100 pounds) or more a t a pH of 8 to 9 for a period of four to 16 hours a t a temperature below 85°F. The increased bleach quantity and time and lower pH are compensated for by the lower temperature. When increasing the quantity of bleach for lower temperature bleaching, use a n antichlor to ensure t h a t the bleach solution is completely exhausted prior to souring. Diluting the bleach

As previously mentioned, historical guidelines are two quarts of a one percent bleach solution per 100 pounds of textiles, depending on oxidizable stain content. For a washer loaded with 600 pounds of fabric, the recommended amount is 12 quarts of one percent bleach. Since one quart of 12 percent bleach is equivalent to 12 quarts of one percent bleach, is using the undiluted bleach concentration acceptable? No, because a concentrated bleach solution added directly into the washer causes serious localized damage to textiles, even during the brief time required to bring about dilution. Using diluted bleach saves textiles in the long run, especially if the bleach stock solution is being poured through the supply door. However, the supply

hoppers or injectors on many present-day machines are too small to accommodate diluted bleach, forcing operators to use bleach concentrations greater t h a n one percent. Therefore, all automatic supply systems must be set to properly dilute the bleach before it comes into contact with the fabric. Supply equipment must be well maintained to ensure proper bleach dilutions. Temperature of the first rinse

The factors operating in the bleach bath also operate in the rinses. If all of the bleach decomposed in the bleach bath, the first rinse wouldn't need to be controlled. But this rarely happens. In practically every case, bleach remains in the fabric and is carried over from the bleach bath to the rinses. For this reason, the temperature of the first rinse should never exceed the temperature of the bleach bath-160°F maximum. Higher temperatures can accelerate chemical decomposition and damage the fabric, depending on the amount of residual bleach. In subsequent rinses, bleach dissipates by mechanical dilution a n d by accelerated chemical decomposition caused by lower pH and higher temperature.

BLEACH MANAGEMENT IN THE LAUNDRY As mentioned, the most commonly used bleach in the laundry is a n oxidizing bleach t h a t releases free (available) chlorine in the bleach bath. Available chlorine may be prepared in the laundry washroom in the following ways. Sodium hypochlorite

Chlorine bleach is most often made by diluting a liquid sodium hypochlorite solution. Concentrated liquid sodium hypochlorite, also known a s "raw bleach," is simply diluted with water to the desired strength. Concentrated liquid sodium hypochlorite is available in five-gallon containers; in 15-,30-, and 55-gallon drums; and in bulk. Currently, concentrated bleach is labelled and sold a t strengths ranging from 10 to 17 percent available chlorine. Liquid chlorine bleach is quite unstable. Generally, it isn't wise to store the bleach in the plant for more t h a n 30 days; storing i t no more t h a n two weeks is even better. Check bleach strength to be sure t h a t each batch received measures up to desired specifications. Refer to Chapter l for determining bleach strength. Liquid sodium hypochlorite varies a great deal in strength a s received from the distributor. In warm weather, bleach supplies frequently don't correspond to strength (available chlorine) on the container label. For a safe dilution, a one-to-12 ratio is a good rule of thumb. For a n y dilution strength, the large number is the total units of volume that includes one unit volume of the concentrate. When the product is labelled 10 or 10.5 percent available chlorine, make a one-to-10 dilution. A one-to-10 dilution is made by taking one volume of raw bleach and combining it with nine volumes of t a p or softened water to make a total of 10 volumes of finished solution. Lithium hypochlorite

Lithium hypochlorite (LiOCI) is available a s a dry powder assaying 35 percent available chlorine. Lithium hypochlorite is readily soluble and provides the

same type of bieaching action as sodium hypochlorite liquid bleach. The powder is hygroscopic (absorbs moisture from air) and loses strength when exposed to humidity. Organic chlorine bleaches

Organic bleaches are relatively recent additions a s laundry bleaches. They're sold in a stable dry form, making them convenient to store and simple to use. The most widely used compounds are derived from either hydantoin or cyanuric acid. A number of chlorinated hydantoin compounds have been prepared and studied. In general, they have low solubility in water but are very effective bleaching agents once dissolved. The most popular is 1,3-dichloro-5,5dimethyl hydantoin. Commercially available chlorinated hydantoin is blended with alkalies (frequently phosphates and carbonates) to provide the desired level of available chlorine, usually less than 15 percent. Four cyanuric acid derivatives are used a s bleaching agents: trichloroisocyanuric acid (TCCA), dichloroisocyanuric acid (DCCA), sodium dichloroisocyanurate (NaDCC), and potassium dichloroisocyanurate (KDCC). TCCA is the least soluble of the four and is used the least often. When dry organic bleaches are dissolved in water, hypochlorous acid is formed. If the bleach bath contains alkaline compounds, the hypochlorous acid is converted by neutralization to hypochlorite, the oxidizing agent found in other chlorine bleaches. The hypochlorite is formed gradually a s the organic bleach decomposes. Potentially, the hypochlorites formed from organic bleaches have the same oxidizing action, weight for weight, a s the hypochlorites found in other chlorine bleach solutions. Because they are formed slowly, however, they do not produce a s high a level of bleaching activity as do the immediately available hypochlorites found in the ordinary chlorine bleach solutions. In some ways, this is a n advantage. Under the same operating conditions, organic bleaches cause less strength loss in cotton fabrics than do the inorganic hypochlorite type bleaches. They tend not to be as effective as inorganic hypochlorite bleaches in removing the more tenacious types of stains when both kinds are used a t comparable concentrations of available chlorine. In treating unbleached cotton goods, the organic bleaches are markedly less Table 4-3: Chlorine bleaches Compound Inorganic: 1. Sodium hypochlorite 2. Calcium hypochlorite 3. Lithium hypochlorite 4. Chlorinated trisodium phosphate Organic: 5. 1.3~ichloro-5.5-dimethylhydantoin 6. Trichloroiwyanuric acid 7. Sodium diisocyanurate dihydrate

Physical form

Available chlorlne (%)

Liquid Powder Powder Powder

5 to 15 70 to 75

Powder Powder Powder

35 3.5 to 4.5 36

90 56to M)

effective than are the hypochlorite bleaches. In routine laundry operations, organic bleaches are added to the washer in dry form a t the bleach bath. Usually one or two ounces are used per 100 pounds of load at the same pH and temperature a s recommended for hypochlorite-type inorganic bleaches. The chlorine bleaches currently used for laundering are listed in Table 4-3. The table also indicates the physical form and percentage of available chlorine. Hydrogen peroxide bleaching

Hydrogen peroxide (H202) was used a s a bleaching agent in many laundries during World War I1 when chlorine bleaches were not readily available. It's still used in textile mills for bleaching fabrics made of various types of natural and synthetic fibers. Compared to chlorine bleach, hydrogen peroxide bleach is more effective on some stains and less effective on others. (Recommendation: Compare the two on actual stains in the plant.) Hydrogen peroxide is less likely to cause loss of color in colored fabric and yellowing. Theseconditions are the result of chlorine retention and subsequent reaction on certain synthetic fibers and textile finishes. Hydrogen peroxide is not as effective as chlorine products in destroying microorganisms. Hydrogen peroxide, like sodium hypochlorite, bleaches by oxidation. Hydrogen peroxide has an advantage over other types of bleaches in that the only residue formed by its action is water. Therefore, there are no salts or other waste materials to be removed by rinsing. Hydrogen peroxide causes less fabric damage in the souring bath if it isn'trinsed thoroughly from the textiles. Experimental studies on hydrogen peroxide bleaches conducted in the laboratory and in laundry operations have revealed the following: H Effect of concentration. When all other factors are kept constant, increasing the amount of hydrogen peroxide in relation to the weight of textiles processed does not bring about markedly increased strength loss as do chlorine bleaches. H Effect of temperature. The activity of hydrogen peroxide bleach increases a s the temperature increases, and there is a corresponding increase in textile strength loss. As with chlorine bleach, the strength loss is low a t temperatures below 150°F, but it becomes more pronounced a s the temperature increases above 160°F. In general, hydrogen peroxide bleach is less damaging than chlorine bleach a t the same temperature. In lowtemperature washing, hydrogen peroxide is not very effective unless an activating agent such as tetraacetyl ethylenediamine (TAED) is added to the bath. H Effect of pH. With hydrogen peroxide bleach, an increase in pH increases bleaching activity, with a corresponding increase in tensile strength loss. This is the reverse of that encountered with chlorine bleaches, where a n increase in pH brings about a decrease in bleaching activity (lower strength losses). Hydrogen peroxide is.available in 35-, 50-, and 70-percent weight solutions. In practice, the equivalent of two quarts of hydrogen peroxide stock solution

assaying 1.0 percent of active oxygen should be used per 100pounds of dry textiles. This corresponds to a bleaching solution concentration of 100 ppm of H202.

The temperature should be approximately 160°F, and the pH level of the bleach bath should be in the range of 10 to 11.5,depending on the type of alkali used. Sodium percarbonate Sodium percarbonate is a combination of sodium carbonate and hydrogen peroxide, with the hydrogen peroxide readily released in solution. The percarbonate powder is shipped in dry form and may be added dry to the washer or dissolved in a stock solution. Sodium percarbonate should be used with the same guidelines a s hydrogen peroxide and is more soluble than sodium perborate. Sodium perborate Sodiumperborate is more easily used than hydrogen peroxide since it is available in solid form and, therefore, can be added directly to the washer a t the bleach bath. Sodium perborate also may be used a s a bleach with results similar to those obtained with hydrogen peroxide. In solution, sodium perborate undergoes chemical change, forming sodium borate and hydrcgen peroxide. This reaction is slow and produces hydrogen peroxide over a more extended period of time than does an equivalent amount of liquid hydrogen peroxide. The hydrogen peroxide formed decomposes, acting as an oxidizing agent for bleaching purposes. Sodium perborate should be used under the same conditions described for hydrogen peroxide, except longer bleach times and a minimum temperature of 160°F are recommended. The oxygen bleaches currently used for laundering applications are listed in Table 4-4. The table also indicates the percentage of active oxygen for each of the bleaches.

-

Table bleaches - 44: Oxvaen ,

Compound Liquid: Hydrogen peroxide 30%(by weight) 35%(by weight) 50%(by weight) 70% (by weight)

Powder: Sodium perborate monohydrate Sodium perborate tetrahydrate Sodium percarbonate Potassium monopersulfate

Active oxygen (%)

FINISHING CHEMICALS

5

F

inishing chemicals are used after the bleaching process. This chapter describes chemicals used in the rinsing, souring, and starching baths.

ANTICHLOR Antichlors are chemically known a s reducing agents. They neutralize chlorine and other oxidizing agents (bleach) on textiles and can also effectively remove some dyes and stains. Of the common antichlors-sodium hydrosulfite, sodium sulfite, sodium bisulfite, and sodium thiosulfate-sodium thiosulfate is the best and safest to use in laundry operations. In the laundering process, antichlor is applied during one of the rinse baths following bleaching to "strip" the last traces of chlorine bleach from the fabric. Low-temperature bleaching operations, in particular, may require an application of antichlor if tests show the presence of chlorine. The normal use rate is one-half to two ounces of product per 100 pounds of textiles. For process water containing high levels of chlorine, antichlor is used in the sour bath. In fact, some laundry sours contain small amounts of antichlor. Antichlor in the sour bath also corrects problems created by textiles with chlorine-retentive finishes. If the retained chlorine is not neutralized by antichlor, the heat of drying or ironing converts the chlorine to a n acid form that is very damaging to textiles-especially cotton.

SOURS The main purpose of the souring operation is to neutralize residual alkalinity with a mild acid or acid salt. Residual alkalinity in textiles is caused by the alkalinity in tap water, carryover from alkalies and detergents, and/or hydrolysis of soap. This residual alkalinity can cause: yellowing of white fabrics, fading or dulling of colors, skin irritation, and/or odors.

Another purpose of the souring operation is to retard iron accumulation in textiles laundered in rust-contaminated water. The souring operation also can help: Iremove some metallic stains, destroy some species of bacteria, set some classes of dyes, and Imaintain whiteness. Sours are some of the most hazardous chemicals commonly used in the washroom. Personnel must be properly trained i n the safe handling and storage procedures specified on the Material Safety Data Sheet (MSDS) for the particular sour being used. A proprietary sour can be a single acidic substance or a mixture of several such substances. Souring agents are available a s dry powders or crystals and a s liquids. Several factors must be considered when selecting a n appropriate laundry sour. Most important are: neutralizing value, Isolubility, and cost per ounce of bicarbonate neutralizers. Other considerations include: type of detergent used, type of washer used, method of dispensing, rust or iron content of the water, alkalinity of the water, and efficiency of the rinsing operation. Neutralizing value is important because the higher the neutralizing value, the smaller the amount of product required to perform a n y given souring task. The cost and neutralizing value are closely related. The neutralizing values of some commonly used sours appear in Table 5-1. The neutralizing value of each sour included in the table is expressed in terms of the number of ounces of sodium bicarbonate required to neutralize one ounce of the sour. Some sours have rust-removing (reducing agent) properties, a desirable trait if the fabric or water contains rust. The solubility of a sour is critical. Low solubility can result in poor distribution in the washer and can cause a buildup on textiles. This gives textiles a poor hand or feel and may result in rolling (tendency of the leading edge of textiles to tightly roll in front of the ironer rolls) in the flatwork ironer. Dry sours are convenient to use but must be weighed or measured with a calibrated scoop to ensure proper quantities. Some dry sours do not dissolve readily in water and, consequently, may cause uneven souring. Liquid sours aren't a s convenient to store or to handle a s dry sours, but they have the advantage of being easier to measure. Since they are already in solution, liquid sours are distributed uniformly and rapidly throughout the textiles when added to the washer. To gain the benefits of both dry and liquid sours, some laundry operators use easily soluble dry sours. By making the solution prior to use, they get the accurate measurement and good distribution of a liquid with the ease of storage and

Table 5-4: Common laundry sours

Sour

Formula

Citric acid Ammonium silicofluoride Sodium silicofluoride Phosphoric acid (75%) Formic acid Zinc silicofluoride Ammonium acid fluoride Sodium acid fluoride Oxalic acid Hydroxyacetlc acid (70%) Acetic acid (56%) Fluosilicic acid (24%)

CaHsO7 (NHa)?SiFa Na?SiFa HsPO4 HCOOH ZnSiFae5H20 NHaHFz NaHF2 (COOH)2.2H>O HOCHLOOH CHjCOOH H?SiFb

Ounces of sodium Rust. bicarbonate Solubility in reacting with ounces per removing one ounce of sour gallon of water propedies 1.86 1.83 1.78 1 68

1.64 1.62 1.47 1.35 1.33 1.19 0.78 0.54

170.2 28.8 0.85 Liquld Liquid 640 33.8 3.7 0.64 Liquid Liquid Liauid

None Poor Poor Poor None Poor Good Good Excellent None None Poor

handling of a powder. This procedure for dry sours is a must for washers equipped with automated liquid supply injectors. Ammonium a n d sodium silicofluoride are the most widely used dry sours. They have high neutralizing values and are sometimes blended with their acid fluoride counterparts to improve rust-removing properties. Zinc silicofluoride is sold in dry form but is sometimes used in liquid systems because of its high solubility in water. Other potential sours have their drawbacks. Formic acid and glacial acetic acid are not used a s sours because of their odor and skin-irritating properties. Formic acid may cause a n allergic reaction in people with bee sting allergies. Acetic acid was once widely used a s a laundry sour, but the bad odor it often produces during ironing h a s caused i t to lose favor. Hydrofluoric acid (not included in Table 5-1) is not recommended a s a laundry sour. Although it's a n effective neutralizer and h a s excellent rust-removing properties, i t is extremely dangerous and skin contact can be fatal. Commercial rust-removing agents may contain hydrofluoric acid and special buffering agents. Oxalic acid also is used a s a rust-removing agent. Oxalic acid must be thoroughly rinsed because any residuecan damage cotton, rayon, and other forms of cellulose. Fluosilicic acid is a fair neutralizing agent and is sometimes used in liquidsupply systems. The acid fluorides have good rust-removing properties, but ammonium acid fluoride, if overused, can cause irritating fumes during ironing. All proprietary laundry sours contain a t least one of the generic chemicals listed in Table 5-1.Other ingredients frequently found in laundry sours include: salt-occasionally added to laundry sours to cut costs. However, this generally is a more expensive alternative than buying nondiluted sour because the laundry operator must use more of the diluted product plus incur additional expense for transporting and blending.

Ioptical brighteners-sometimes

added to sour in minutequantities. They add little cost but significantly increase textile brightness. lubricants-added to some laundry sours to help keep washer doors from sticking when synthetic detergents are used. Lubricant additives range from expensive carbowaxes to simple tallow soap.

FABRIC SOFTENERS Fabric softeners have been used in textile manufacturing and finishing for many years to improve feel-or hand-and suppleness, and to reduce harshness of fabrics. At one time, about the only textile maintenance operators to take advantage of these obvious benefits were diaper services. Now most launderers use softeners because they also act a s lubricants, speeding extraction and conditioning, improving shake-out prior to ironing, reducing or eliminating ironer static, and generally increasing fabric and zipper life. Structure Softeners used in the textile rental industry are available a s concentrates in paste, liquid, and dry form. They also can be purchased in ready-to-use liquid form (diluted with water or alcohol) or dry (diluted with urea or salt). Commercial products are usually cationic surfactants, while consumer products rely increasingly on nonionic softeners. Cationic surfactants are better softeners for the textile rental industry than are nonionic products because their positively charged ions create high substantivity-ability to be attracted to the textile surface-with cotton. This is due to the fact that cotton, when wet, becomes negatively charged, attracting and holding the cationic softener on its surface. Most fabric softeners are prepared from fatty acids found in tallow, mainly stearic acid, because the tallow-based compounds are the most effective softeners. The chemical structure of these quaternary compounds is two long-chain units [CHs (CH&7] attached to the central nitrogen atom and two methyl (CH3) groups. (Quaternary germicides, on the other hand, contain only one fatty derivative of shorter chain length.) Many variations of this chemical structure-involving different raw materials and different anion combinations-are used in the textile manufacturing and maintenance industries. However, all cationic textile softeners are fundamentally similar in that they: Iare quaternary nitrogen compounds, Ipossess two long-chain fatty substituent fragments, and Iprimarily are derived from tallow fatty acids. How softenerswork Two explanations of how fabric softeners/lubricants work are: 1. The cation moves toward the interior of the fiber, leaving the two long chains (tails) exposed, which causes a smooth and soft feel and bulking.

Since fabric softeners are humectants-substances that absorb moisture from the surrounding environment-they cause the textiles to contain enough moisture to discharge any accumulated surface electricity, reducing static electricity. Instructionsfor use Fabric softeners should be used under the following conditions: application point-sour bath Itemperature-90" to 115°F IP H - ~to 7 Iwater level-low (supply level) Itime-4 to 6 minutes. Fabric softeners are added during or after the sour bath. They are easily absorbed by cotton from water and remain in the fabric until laundered again. Laboratory studies show absorption is completed in six minutes or less under normal conditions. However, fabric softeners can be overused. Overuse causes fabric to lose its water absorption capabilities. Using cationic softeners on polyester can result in alkaline hydrolysis even without overuse (see Chapter 3). Normally, water absorption isn't lowered noticeably when softeners are addedto the point a t which they lubricate. However, a t levels in which softening occurs, water absorption can be affected-sometimes dramatically. Two quick and easy tests-the sink test and the drop test-are used to check for water-absorption problems. The sink test works a s follows: 1. Fold the treated fabric into a packet and drop it onto the surface of cold water. 2. Note the amount of time the packet takes to completely submerge. Clean, untreated cotton textiles normally will sink in seven to 15seconds. As softener is added, sinking time increases. Sinking time up to 45 seconds is acceptable for general use. For the drop test: 1. Drop a drop of water onto the surface of a flat piece of softened fabric. 2. Note the amount of time the water takes to disperse. For general use, the drop of water should dispersein less than three seconds.

Caution: Residual detergent will cause faulty test results. Detergent decreases both the sink and drop penetration times.

CHEMICALS THAT CONTROL MILDEW AND BACTERIA Good laundry practices produce clean textiles, meaning textiles free from soil and stains. Another function of laundering is to substantially reduce bacteria, fungi, and other microorganisms, both pathogenic(capab1e of causing disease) and nonpathogenic, to help control the spread of infection and disease. However, since textiles can be recontaminated after laundering, antimicrobial agents are sometimes added to the washer. These agents are absorbed by the textiles and kill or inhibit the growth of microorganisms that might recontaminate the textiles. Three broad classes of microorganisms must be dealt with in laundering: 1. Gram-positive bacteria. In general, gram positives areindigenous to the

upper respiratory system and skin of humans; Staphylococcus aureus ("staph") are one example. 2. G r a m - n e g a t i v e b a c t e r i a . These are sometimes referred to a s soil bacteria and are associated with human intestinal waste; e.g., Escherichia coli (E. colil are found in large numbers in fecal matter. 3. Fungi. These microorganisms are responsible for mildew formation in textiles. They're very troublesome, especially during the warm summer months and in warm, humid climates. Antimicrobials fall into two categories: bactericides or mildewcides are capable of killing microorganisms; bacteriostats or mildistats disrupt the reproduction of microorganisms and prevent rapid increase. For laundry use, the ideal antimicrobial agent should: W be broad spectrum (able to kill or control a wide range of microorganismsgram positive, gram negative, fungi, and spore formers), W not be easily neutralized by soil (e.g., body waste and excrement), W have minimal toxicity to humans, W not produce undesirable side effects (not weaken or stain fabrics, irritate skin, or discolor fixtures, tile, etc.), and I have a low cost-per-use index. While antimicrobial agents tend to be selective in their activity, they all are somewhat effective if applied a t a high enough concentration. General guidelines are t h a t less microbial is needed to control Staphylococcus aureus (gram positive) t h a n to control Escherichia coli (gram negative), while more antimicrobial is required to suppress the activity of mildew-producing microorganisms t h a n gram-positive or gram-negative organisms. The amount of antimicrobial needed depends on: W the concentration of the product, W the length of time protection is needed, and W the type of microorganism to be controlled. Antimicrobial products sold to the laundry industry are registered with the U.S. Environmental Protection Agency (EPA) and must carry evidence of this registration on all product labels. In addition, label content for a n y antimicrobial sold in interstate commerce is controlled by regulations promulgated in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Act mandates that labels show: W the supplier's EPA registration number, W the chemical composition and concentration of all active ingredients, and W the proper dose rate and treating procedures for controlling specific microorganisms. The activity of any antimicrobial varies with the chemical nature of each ~ r o d u c tand with the concentration of active ingredients. so the directions printed on the label must be followed. Using the amount specified is very important because underdosing may allow certain organisms to mutate and develop a resistance to even higher levels of the antimicrobial product. This resistant behavior of mildew organisms h a s been confirmed in research studies. Once the mutating cycle begins, it can be broken only by using chlorine bleach. To lessen the likelihood t h a t mutated resistant strains will develop, the

-

antimicrobial active ingredient must be changed once or twice a year. Bleaches, while not true anti-bacterials, are effective in mildew control. Chlorine bleach removes the color pigment from mildewed areas. Oxygen bleaches also seem to be able to remove the mildew pigment color but are not a s effective a s chlorine in destroying the mildew organism. The classes of chemical compounds currently used a s antimicrobials are limited by environmental a n d safety considerations. For example, tin a n d mercury compounds effectively control or kill many organisms, but they are hazardous to humans. The major types of chemicals available for laundry use are described below. Quaternaw ammonium C O ~ D O U ~ ~ S ~ u a t e r n aammonium i~ bactkriostats are simliar in chemical structure to quaternary ammonium fabric softeners with two key differences: they contain only one fat-derived group attached to the nitrogen atom, in contrast with the two fat-derived groups found in fabric softeners, a n d the fat-derived group h a s a shorter carbon chain length. Quaternary bacteriostat agents share basic chemical properties. They: are quaternary nitrogen compounds, have one long-chain fatty substituent, and are primarily derived from coconut fatty acids [CH~(CHZ)II]. Quaternary bacteriostats are applied in the sour bath. The bacteriostat is absorbed from the sour bath and remains with the textiles until subsequent laundering. They are neutralized by tallow soap and anionic detergents but are not affected by nonionic detergents or alkalies. Quaternary bacteriostats should be used under the following conditions: application point-sour bath temperature-90" to 115OF pH-5 to 7 water level-low (supply level) time-4 to 6 minutes. Labels for these compounds indicate the chemical structure of the active ingredient. For example, a label stating, "active ingredients: n-alkyl(68%C12, 32%C14) dimethyl ethylbenzyl ammonium chloride," refers to a quaternary ammonium component in which two methyl groups, one ethylbenzyl group, and one n-alkyl (fatty group) are attached to the nitrogen atom. The n-alkyl group is composed of a mixture of Clz and C14 chain lengths. lsothiazolone derivatives I n studies conducted a t the University of South Carolina in Spartanburg to evaluate the effectiveness of mildew control agents, one class of compounds was found to be more effective t h a n quaternary ammonium compounds in controlling mildew-forming organisms. The study included five agents based on various forms of quaternary ammonium compounds, two based on octhilinone (2-n-octyl-4-isothiazolin-3-one), and one based on methylene bis-thiocyanate. Only the two agents containing 2-n-octyl-4-isothiazolin-3-onewere ranked a s excellent for mildew control (other forms of isothiazolone were not included in the study).

For best results, octhilinone mildewcide (2-n-octyl-4-isothiazolin-3-one)is used in the final rinse water operation. This minimizes the chance that it will be rendered inactive by other chemical additives, such as antichlor or chlorine. Mildew organisms can occur on both natural and man-made fibers. But cellulosic fibers such a s cotton provide the greatest nutrient source for mildew and, therefore, are the most likely to attract mildew and suffer the greatest textile strength loss. Soils and sizings on synthetic fibers such a s polyester may attract mildew and promote its growth. However, a mildew stain doesn't automatically indicate fiber damage.

SIZING Sizings give body to fabric, improve hand or feel, and impede soil and stain penetration. Sizings are: starch, I synthetic polymers, or a combination of these. Most starches are made from wheat, corn, or rice. Practically all proprietary laundry starches also contain a small percentage of waxes, sulfonated oils, or other additives that aid starch penetration and increase the pliability of the finish. The most commonly used synthetic polymer is polyvinyl acetate, although new synthetic fiber sizings are appearing on the market. Polyester and cotton are the most commonly used fibers in the textile rental industry. Since cotton is a hydrophilic fiber, it readily accepts starch. Polyester is usually sized with synthetic polymers or mixtures of starch and polymers. Polyester fibers that have been modified to increase the wettability of the fiber most readily accept sizing. Regardless of the type of starch or sizing used, both cotton and polyester perform better if the fibers are thoroughly clean before the sizing is applied. Raw and cooked starch

Cooked starch generally i s preferred to raw or uncooked starch because it can be applied more uniformly, penetrates the fabric better, and gives a better hand and finish to fabrics. Raw starch exhibits unusual behavior when mixed with water and heated (cooked). The tiny starch granules swell until they are many times their original size. As the swelling continues, the granules distend and their outer layers finally break. This releases very small particles of starch material that become suspended in the water to form a smooth, creamy mixture. If starch isn't cooked sufficiently or is used raw, only a portion of these granules disintegrate, resulting in a sticky, viscous mass that doesn't coat fibers evenly. This uneven coating can cause difficulty in ironing, resulting in highlights and sticking on ironer and press. Uncooked starch is used by plants that do not have cooking facilities. It is also used with cooked starch to give more body and added stiffness to fabrics. Thin-boiling starch, which is used on shirts and uniforms, usually is a mix:

ture of wheat and corn starch. Many operators prefer rice starch for a very high-quality finish because it doesn't congeal after cooking and, therefore, doesn't require rewarming to use. Thick-boiling starch contains a large proportion of corn starch and must be kept warm after cooking until used. The formula for thin-boiling starch is eight to 10 ounces per gallon of water in the stock mixture. The formula for thick-boiling starch is four to six ounces of starch per gallon of water. The amount of starch added to the washer depends on the nature of the items being starched and on the desired hand on the finished fabric. Starch should be used under the following conditions: application point-last washer operation while the washer is running temperature-90° to 120°F water level-cooked starch: very low water level; dry (raw) starch: regular low level time-6 to 10 minutes For best results, starch is added during the last washer operation to a low water level while the washer is running. In many plants, the starch operation is combined with the sour step and may also include mildistats, softener, and antichlor. Be sure to allow adequate dispersion time, otherwise starching will be uneven and will cause starch accumulation on ironers and presses. When thestarching operation is complete, drain the solution with the washer running. When preparing and using a conventional starch in the laundry, pay special attention to these guidelines: Starch should always be prepared according to a standard procedure. Measure the required amount of starch carefully so that the amount of starch per finished gallon always is the same. Cook starch for a t least 20 minutes after active boiling has begun to ensure complete breakdown of the starch granules. Do not add freshly prepared staich to an old batch of starch. This is a poor attempt a t economy. Keep the starch cooker clean and free from rust to prevent discoloration of the starch, avoid decomposition, and prevent bacteria growth. Clean the cooker thoroughly before each use. Be sure containers used to transfer the starch from the stock supply to the washer area are clean and free from rust. Maintain starch loads a t uniform weights to obtain consistent results. Do not overload washers or individual nets; this leads to poor distribution and uneven starching. Watch for mildew. Starch provides a good nutrient source for microorganisms and may increase the rate of mildew formation.

Modified starch Many companies offer corn and wheat starches in a form that can be added "dry to the wheel." These products have been chemically modified orpregelatinized for rapid dispersion in water.

Although modified products offer a more convenient method of starch management and application, in general, they produce a lower quality finished product. Synthetic polymer sizings Some polymer sizings are water emulsions of polyvinyl acetate polymer. The products vary in the concentration and the molecular weight of the polymer. Polyvinyl acetate is more difficult to remove from fabrics in subsequent washing than is starch. For this reason, polyvinyl acetate h a s a tendency to accumulate and develop a harsh feel on the fabric. Polyvinyl acetate also can cause fabrics to discolor and to retain soil and odor; polyvinyl acetate also can accumulate on press and ironer surfaces. To offset some of these problems, many proprietary formulations consist of modified polyvinyl acetate and blends of polyvinyl acetate with other polymers or starches. Many of these problems have been addressed by a new generation of synthetic sizings. However, additional information on thesenew synthetic sizings wasn't available for this edition.

SOIL-RELEASE FINISHES Soil-release finishes are classified a s durable or nondurable. The durable types of soil-release finishes are applied during fabric manufacturing. These finishes are intended to function for the useful life of the fabric. The nondurable soil-release finishes usually are applied in the washing process. Nondurable finishes coat the fiber during a rinse or sour operation, and the fabric retains this coating until the next washing. As the fabric becomes soiled, the soil does not bind a s strongly with the fiber because of the film between soil and fiber surfaces. Film and soil are then removed more easily during the next washing. Several materials including starch, polyvinyl acetate, and polyvinyl alcohol have the ability to function a s nondurable soil-release finishes if properly applied. PROPRIETARY FINISHING CHEMICALS Proprietary sours, softeners, sizing, and other products are based on one or more of the generic materials described in this chapter. In general, proprietary products also contain optical fabric brighteners. Some proprietary products combine different products. For example, one product may combine softener and bacteriostat or softener and sour. Multifunctional products offer the following advantages and disadvantages: AdvantagesOnly one product instead of several must be purchased and stored. Chance of washroom personnel forgetting one of the chemicals is reduced. Amount of required dispensing equipment may be reduced. DisadvantagesICould be more costly. Recommended use may cause underuse or overuse of one of the chemicals.

TEXTILE FIBERS, FABRICS, AND FINISHES

T

he purpose of this chapter is to summarize the nature of textile fibers t h a t may be encountered in a textile rental plant or related operation plus their chemical and physical characteristics, uses, and limitations. Many of the fibers included in this chapter are not frequently found in t h e professional laundry but are included to provide a complete list of fibers available.

CLASSIFICATION OF TEXTILE FIBERS Although fibers may be classified in several ways, a logical division is natural fibers and man-made fibers. Natural fibers used to make textiles occur in nature in fibrous form. Cotton, probably the most common natural fiber, is composed of cellulose (C,2H20010)X. Cotton fibers and other forms of cellulose can be dissolved chemically a n d regenerated to produce rayon. Both cotton and rayon have many properties i n common. Natural fibers also may be treated with a finish to alter characteristics such a s crease resistance, flammability, and luster. Man-madeor synthetic fibers are made synthetically by chemically combining elements or compounds (simple or complex) such a s petroleum products; they're also made from chemically regenerated natural fibers. With a few exceptions, textile fibers are composed of molecules called polymers. A polymer is a very long molecule formed when several smaller molecules link together in a regular, repeating manner that defines the combination of elements and determines many fiber proportions. The number of repeating units making up the polymer is termed the degree of polymerization.

FIBER NAMES One of the provisions of the Textile Fiber Products Identification Act (TFPIA) requires t h a t fibers be identified using "generic" names for man-made fibers and "commonly accepted terms" for natural fibers. The generic terms for m a n made fibers are based on the structure of the polymer repeating unit only. As of 1988,23 generic names for man-made fibers existed under Rule 7 of the TFPIA:

acetate acrylic anidex aramid azlon glass lastrile metallic

modacrylic novoloid nylon nytril olefin PBI polyester rayon

rubber saran spandex sulfar triacetate vinal vinyon

In addition to the 23 classes above, several new fibers have not yet been classified. To establish a new generic name, manufacturers must apply in writing to the Federal Trade Commission. New generic names are added to the list a s the commission approves them. Man-made fibers formed by combining two or more generic classes of polymers a s the fiber is made are classified according to how the polymers are combined. These are called: B bigeneric, bicomponent, biconstituent, or W matrix fibers. Manufacturers of these fibers must indicate the generic name of the components used to make the fiber. For example, fabric made from a matrix fiber composed of 50 percent vinyon and 50 percent vinal must be labeled: 100 percent matrix fiber (50 percent vinyon/50 percent vinal).

NATURAL FIBERS Natural fibers are not classified by any universal method, so a logical choice is to classify them according to their origin. This system includes three broad categories of fibers: Icellulosic, H protein, and W mineral. Cellulosic fibers Cellulose is the primary solid substance in most plants. However, only certain sections of some plants provide fibers that are suitable for making textiles. Fibers that grow from the plant seed are called seed hairs. In the case of cotton, the seeds and seed hairs are combined in a boll. Other suitable seed hairs come from milkweed, kapok, and cattail. Fibers that are found in the stalk of the plant are called bast fibers. These include flax, ramie, hemp, jute, and urena. Leaf fibers suitable for textile use are obtained from abaca, pineapple, agave, palm, and yucca plants. Fibers found between the husk and the nut of the coconut, referred to as nut husk fibers, also have been used for textile items. Protein fibers

Protein fibers are obtained from animal hair, fur, or secretions. The largest category of protein fibers come from animal hair and include

wool (sheep),alpaca, camel, cnshmerc, guanaco, llama, mohair (Angora goat), vicuna, mink, muskrat, and Angora rabbit. In 1939, Congress passed the Wool Products Labeling Act (amendedin 1980) "to protect producers, manufacturers, distributors, and consumers from t h e concealed presence of substitutes and mixtures in spun, woven, knit, felted, o r otherwise manufactured wool products." This act requires products containing wool to be labeled a s to whether the wool is new or recycled. The term "wool" as defined by the Act, is a fiber grown naturally as the coat of a living animal. Since the Act does not specify sheep as the sole source of wool, any fibers classified a s animal hair fibers can legally be labeled a s wool. However, most products labeled a s wool are derived from sheep. Manufacturers have the option, and usually prefer, to specify the animal of origin if other than sheep. Protein fibers made from animal secretions include all varieties of silk from cultivated or wild silk caterpillars or spiders.

TEXTILE LABELS A wide variety of labels are attached to textile products, especially wearing apparel. Many of these labels are required by federal legislation. A brief summary of the major labels required for the textile rental industry follows: H The Wool Products Labeling Act of 1939 (amended in 1980) requires labels for wool or part-wool products to indicate whether the wool content is new wool (called wool, virgin wool, or lambs wool) or recycled. H The TFPIA requires most textile products to be stamped, tagged, or labeled with: 1. the fiber or combination of fibers used in the item identified by generic name (man-made fibers) or common name (natural fibers). All fibers must be designated with equal prominence. 2. the percentage by weight of each fiber present, excluding ornamentation and fibers not exceeding five percent by weight of the total fiber content. Percentages must be accurate within a tolerance of three percent of t h e total. 3. for upholstered products, information on whether the stuffing has been used a s stuffing in another upholstered product. 4. the name or other identifying mark of the product's manufacturer. 5. if the item is imported, the name of the country of origin. 6. other items of information, such a s fiber trade names, a s long a s they don't violate the Act. U Fabric flammability standards currently are in effect for entrance mats, carpets and rugs, mattresses and mattress pads, and some clothing. Labels must specify how much flammability protection can be expected from t h e item. Since laws and regulations may change, operators must consult current requirements to ensure compliance.

COMMON FIBERS ENCOUNTERED IN PROFESSIONAL LAUNDRIES Not all of the fibers mentioned so far are used in products processed by the professional launderer. The ones most often encountered are listed on the follow-

ing pages in alphabetical order. Acetate Acetateis used in blends with cotton or rayon a s well a s with other fibers. When blended with nylon or acrylic, it imparts a softer hand to the fabric. Acetate has many excellent characteristics. It resists shrinking, spotting, and staining. I t dries quickly, h a s a soft, natural feel, isn't attacked by moths, and is mildew resistant. On the other hand, acetate is thermoplastic, meaning it softens or melts when exposed to heat above 350°F and must be pressed or ironed with extreme care. Acetate burns readily and melts while burning, leaving a blackened residue. In addition, temperatures from 194' to 225OF cause acetate to lose strength. Acetate decomposes when exposed to strong acids and weak organic acids such a s acetic acid and perspiration. Strong alkalies cause swelling and loss of fiber strength, while acetone and solvents used in fingernail polish removers and lacquers dissolve acetate.

Figure 64:Nonmercerized cotton' Cross-section 5OOX

Figure 62: Mercerized cotton Cross-section500X

Aramld

Aramid was first introduced as a type of nylon but has properties very different from most nylons - it's very strong and highly heat resistant. In 1974, the generic definition for nylon changed, and the generic term aramid was added to the TFPIA. The most common trade names for aramid are Nomex and Kevlar (duPont trade names). Aramid is used in applications requiring high strength and/or heat resistance. Nomex is used in covers for laundry presses and ironers, fire fighters' apparel, and flame-retardant furnishings for aircraft. Kevlar is used to reinforce radial tires and to manufacture cables, body armor, and gaskets. Cotton Cotton fibers usually vary in length from three-quarters of an inch to one and one-half inches. In general, the longer the fiber (staple length), the better the quality of the textiles. While cotton fiber has very little tendency to shrink, cotton fabrics do. Shrinkage occurs when cotton fabric "relaxes" from beingstressed. The fiber can be stressed - stretched or elongated - up to about seven percent, usually in manufacturing. The shrinkage caused by this relaxation commonly occurs during the first washing cycle and may be a s great a s 15percent. Once the fiber has relaxed, no more shrinkage should occur. Mercerized cotton has undergone a strong caustic solution treatment to cause permanent swelling of the fiber. The swollen fiber has a high luster and increased strength. Mercerizing and relaxation shrinking offabric increase the number of yarns per inch, causing the fabric to seem to gain in strength. Cotton material, especially when coated by foreign organic matter such as starches and gums and when stored in a warm moist atmosphere, is likely to be attacked by certain low-order plant organisms, known a s mildew. Mildew discolors and decreases the strength of cotton.

Longitudinalview 5OOX

Longitudlnaiview 500X

Water a t the boiling temperature or below has no effect on cotton fiber other than to soften it and cause it to swell. The action of hypochlorite on cotton varies according to the concentration and temperature. Hypochlorites are used extensively for bleaching cotton. When properly controlled, they are also effective for sterilizing and for removing oxidizable stains. Hypochlorite solutions will damage cotton if the concentration (with respect to the amount of available chlorine) is used a t too high a temperature or a t too low a pH. Cellulose converts rapidly to oxycellulose with a n accompanying weakening or even destruction of the fiber. In addition, hypochlorite solutions should be used judiciously on colored cottons because they can damage dyes. Alkali solutions, even a t boiling temperatures, do not weaken cotton fibers. However, fibers can be damaged during high-temperature drying and ironing *Figures 6-1 through 6-8 are copyrighted by the American Association of Textile Chemists and Colorists.

if strong residuals of alkali are left in the fabric. Proper souring prevents this damage. In general, concentrated mineral acids damage cotton severely and, in many cases, destroy it completely. Cold dilute mineral acids have less action on cotton if the last traces are washed out. Hot dilute acids, such a s sulfuric acid, weaken cotton if left in contact with it for any length of time. Volatile organic acids, such a s acetic and formic acids, have less effect on cotton a t o r d i ~ a r ytemperatures; but a t high temperatures, they may damage the fiber. These two acids were widely used a s neutralizing or souring agents but have been discontinued because they have unpleasant odors. Excessive use of some types of sours can lead to acid damage during hightemperature drying and ironing. Flax (linen)

The flax plant, which normally has a single stalk with a few branches, gmws to a height of several feet. The fiber itself occurs in the inner bark of the plant. As would be expected, the quality of the fiber depends on the type of flax grown (coarse or fine), seasonal conditions, and the time and manner of harvesting.

The color of unbleached flax varies from cream to gray, depending on previous treatment of the fiber. Bleaching may make linen snow white, but t h i s tends to weaken the fiber. Consequently, linen often is used at various stages of bleaching, such a s half-bleached, quarter-bleached, or unbleached. Linen fibers have a high cellulose content and are uniform in thickness - 12 to 25 microns or millionths of a meter. They may vary in length from a few inches to nearly five feet, depending on the manufacturing process. Like cotton, linen is decomposed by hot solutions of strong acids and by oxidizing bleaches. The first action of the acid or bleach i s to weaken the fiber. Strong alkaline solutions do not cause much weakening of the linen fiber unless the solution is hot. Linen, when subjected to a temperature of 300°F or more for any length of time, gradually turns brown and weakens. At 500°F, linen fibers decompose rapidly. Nylon

Nylon was the first truly synthetic textile fiber to find practical use. The averFigure 6-4: Bright nylon

Figure 6-3:Flax (linen)

Figure 6-5: Low-modificationratio trilobal nylon. 15 denier per filament, bright luster

Cross-section500X

Longitudinal view 50OX 76

Longitudinal vlew 500X

Longitudinalvlew 250X 77

age diameter of nylon filaments is 18.5 microns. It can, however, be madeinto a wide range of diameters varying from less than 10 microns up to the size of brush bristles. Nylon is inert to practically all organic acids. However, mineral acids, such. as hydrochloric and sulfuric acids, tend to degradenylon fibers. A boiling solution of five percent hydrochloric acid makes nylon brittle and ultimately causes complete disintegration. Cold, concentrated nitric acid rapidly decomposes nylon. The various alkalies have no effect on nylon because it is very resistant to alkaline substances a t all concentrations. Soaking nylon in a three percent concentration of hydrogen peroxide or sodium hypochlorite a t room temperature for 10 hours has no effect on the fiber.

Figure 6-6: Low-modificationratio trilobal polyester, 1.4 denier perfilament, semidull luster

Olefin

The generic term olefin includes several polymer structures, the most common being polyethylene and polypropylene. A wide variety of properties a n d products belong to the olefin category of fibers. Olefin fibers have the lowest specific gravity of the textile fibers. The fibers are not absorbent but do have the ability to wick (move) moisture. Olefin can be used in apparel fabrics (underwear, socks, sweaters), home furnishing fabrics (carpets, draperies, upholstery), andindustrial fabrics (dye nets, laundry bags, etc.). Polyester

Polyester is currently the most commonly encountered man-made fiber in the professional laundry. Textiles c a n be constructed of 100 percent polyester or polyester in blends with cotton, wool, or other fibers. Polyester fibers are manufactured in both filament and staple length and in a variety of textured shapes. Yarns made from staple textured polyester look very similiar to natural fibers. The widespread use of polyester fibers h a s generated many revisions in equipment and formulas used by professional laundries. Polyester fibers are durable, resilient, hydrophobic (have no attraction for water), and strong. They are very resistant to most chemicals, including strong sour and bleach solutions; but they can be damaged by strong alkalies, especially a t high temperatures a n d in the presence of quaternary ammonium compounds, such a s some fabric softeners. Polyester and polyester blends are unusually resistant to wrinkling. Polyester h a s high crease-retention properties, a n d so-called "permanent" creases and pleats can be pressed into polyester fabrics. Although polyester fibers aren't attacked by moths or mildew, they can be stained by mildew. I n addition, unmodified polyester tends to attract and hold oily soils, frequently resulting in discoloration and odors. Polyester fibers are constantly being modified to improve moisture absorbency, release of oily soil, and texture in order to provide the textile industry with a wide variety of properties and uses for the fabric. Ramie

Ramie is a natural fiber obtained from the stalk of the ramie plant, also known

Longlfudlnal view 250X

a s rhea or China grass. Ramie h a s a higher luster a n d absorbency t h a n cotton, but the fiber is stiffer and may rupture if repeatedly folded in the same place. The fiber h a s a naturally high resistance to insects a n d microorganisms, including mildew, and h a s been used with some success in butcher's aprons. Rayon

Rayon refers to filaments made from solutions of chemically treated cellulose. The cellulose solution is forced through a tiny opening or orifice and is solidified to form a filament. Rayon fibers are made a s a continuous filament and a s a staple fiber. Rayon fibers are made in three grades of luster: bright, semi-dull, and dull. The degree of luster obtained depends on the amount of pigments added while the rayon is in solution. The most common pigment added to control luster i s titanium oxide.

f

!

light, weathering, and temperatures up to 500°F. The fiber is used in industrial felts, filter fabrics, packing materials, gaskets, garment press covers, and some protective fibers. Some barrier fabrics contain a thin film of polytetrafluoroethylene for liquid and particulate protective applications.

Viscose rayon, regular Figure - 6-7:Cuprammoniumrayon. 1.3 Figure 6-8:tenacity, bright denier(0.14 tex) per filament, bright luster Cross-section500X

t

I

I

!

I

Longltudlnal view 250X

Longitudinal view 500X

At 300°F, rayon yarn loses strength; it decomposes a t 350' to 400°F. Rayon does not melt, but it ignites rapidly, giving off little odor and leaving only a small amount of ash. As with cotton, rayon tends to disintegrate when exposed to either hot or cold mineral acids. However, while strong solutions of alkalies have no effect on cotton, they will cause rayon to swell and lose strength. Strong oxidizing agents attack the fiber and cause degradation. Solutions of hypochlorite or peroxide do not damage rayon unless used improperly. Polytetrafluoroethylene Polytetrafluoroethyleneis not currently defined by theTFPIA. Under the trade

name Teflon, the polymer is commonly used for non-textile applications. As a fiber, the polymer is heavy; tan to white in color; and resists chemicals, sun-

1

STRUCTURE OF FIBERS, YARNS, A N D FABRICS Fibers are produced i n either staple (short fiber suitable for spinning) or filament (long, continuous fiber) lengths. Cotton, wool, flax, and most natural fibers are available only in staple form. Silk and most man-made fibers are available a s filaments. It is common practice to cut or break filament-length fibers into staple-length fibers for spinning into fabrics. Man-made fibers are produced by wet spinning, dry spinning, or melt spinning. All three processes use a spinneret, a corrosion-resistant disc containing from one to thousands of tiny holes. Rayon is produced by wet spinning. Purified cellulose is chemically transformed into a solution that is pumped or extruded through a spinneret. As the rayon filaments emerge from the spinneret, they pass directly into a chemical bath where they are solidified or "regenerated." Acetate and triacetate are produced by dry spinning. As acetate and triacetatefilaments exit the spinneret, they are solidified by being dried in warm air. Polyester and nylon are produced by melt spinning; the polymer material that forms the fiber is melted for extrusion and solidified by cool air. Man-made staple fibers are produced by first extruding many continuous filaments from the spinneret in a large rope-like bundle called tow. The spinneret often has as many a s 200,000 holes. These tows are crimped and mechanically cut into staple lengths, which are used as is or blended with other staple fibers, either natural or man-made. At the spinneret stage, fibers can be extruded in different shapes such a s round, trilobal, and octagonal. With man-made fibers, different materials are blended or combined. During the extrusion step, two different polymers can be laid side by side in a single fiber to create a bicomponent fiber. During or prior to extrusion, polymers can be mixed together to form a biconstituent or matrix fiber. In addition, other ingredients t h a t give the fibers specihl characteristics - anti-static, flameretardant, or color - can be added to the polymers prior tc? extrusion. After they're produced, fibers are converted into yarns for weaving or knitting. Some types of yarns are: spun (staple fibers), monofilament (one filament), multifilament (two or more filaments twisted together), or core spun (staple fibers twisted around a multifilament). The yarns may contain only one fiber type or a blend of two or more fibers (both natural and man-made). Man-made yarns are frequently texturized to give them more bulk. Many means can be employed to texturize yarns, including using stiffer boxes, crimping edges, and increasing heat or moisture sensitivity of bicomponent fibers.

Figure 69:Fiber shapes from the spinneret (courtesy of Samina Khan)

Yarns are usually converted into fabrics either by weaving or knitting. Weavinginterlaces two ormoresets of yarns, oneof which is always atright angles to the other sets. The set of yarns that runs the long dimension of a roll or bolt of fabric forms the warp, and theindividual warp yarns are called ends. A second set of yarns interlaced a t right angles to the warp in a predetermined pattern is referred to a s filling, weft, or woof. Individual filling yarns areidentified a s picks. Enlarged views of basic weaves are shown in Figure 6-11 through 14. Elaborate designs can be produced in woven fabrics by combining these basic weaves. Knitting forms a fabric by interlocking loops of yarn. The two basic types of knitting machines are weft and warp. Weft knitting forms fabric by interlocking loops of yarns across the width of the fabric. Weft knits may be single or

Figure 6-10: Blending of cotton and polyester fibers*

As the polyester and cotton fibers are blended during the finisher drawing operation, the blend becomes more uniform. This illustration, taken with ultroviolet light, clearly shows the presence of the fwo fiben and the resulting blend as the drawing operation proceeds from the feeding of the individual fiber slivers to the final blended sliver and to the roving.

double and plain or patterned. In warp knitting, loops made from each warp yarn are formed along the length of the fabric. Warp knits are usually formed i n a flat, single layer and can be plain or patterned. The essential elements of knitted fabrics are described in Figures 6-15 and 16.

*Figures 6-10 through 6-16 copyrighted by Spring Mills, Inc.

Figure 6-4 4: Plain weave fabric

Wisucrl dr'rngonal changes direction to form patfern

Figure 6-42: Right-handtwill weave fabric (2x2)

Visual diagonal moves from upper right to lower leff

84

Fiaure &14: Satin weave fabric

Warp yarns 'Yloat"over several filling yarns to produce gloss or sheen.

85

Figure 6-45: Comparison of weft and warp knit stitches

Figure 646: Types of stitches and structures REGULAR KNIT STITCH

Wen knit stitch components: Jersey structure

Weft knit

back

face

Rib structure

face

back

Wen and warp knit stitches:

Weft knit loop

Warp knit lap

Kniffedfabric construction begins with the formation of a series of Imps from the yam. The loop is, therefore, the fundamentalelementof all knlffed fabric.Loops are of two fypes - the needle Ioop and the sinker Imp. Sinker loops connect adjacent needle loops. In weft knitting, needle loops are drawn through needle loops in the row below. In warp knitfing, the needle loops are drawn through Ioops below and to the side. Theloop in a warpknit differs somewhat in its configuration from the loop in a weft knit. The difference in the interlooping can be seen clearly in this diagram. Loops can also be identifiedasopen or closed.An open loop is one in which the yarns do not cross at the neck or botfom. Open Imps are used in weft knitfing. A closed Ioop is one where the yarns cross at the base. Warp knit loops are examples of closed loops.

TEXTILE DYEING, PRINTING, AND FINISHING As fabrics exit the weaving or knitting machine, they are dyed, printed, or finished. Dyeing and printing contribute to the beauty of fabrics. Finishing makes them better suited to the purposes for which they're intended. However, poorquality material can't be made good through dyeing, printing, or finishing. Here, a s in weaving or knitting, the quality of the fabric begins with the quality of the fiber or yarn. White fabrics (especially cotton and cotton blends) are blended to obtain maximum whiteness. Cottons are commonly mercerized - a finish that adds luster, eases dyeing, and adds strength.

Tuck stitch

miss st~tch

Textile items can be dyed in various stages of manufacture and by many methods (washroom dyeing methods are described in Chapter 7). One method is to dye yarn in pressure becks or vats where dye is forced through the yarn by high pressure. Depending on the sizeof the beck, from 140 to 180 yarn packages can be dyed. Each yarn package holds 20,000 to 40,000 yards of yarn. Fabric frequently is dyed in atmospheric dye becks, J scrays, or by padding. In these procedures, the dye penetrates the fabric by wicking, which is less effective than the pressure method. In another method, color is applied to fabrics by printing it onto the surface. The most common commercial method of printing uses rollers; each roller usually adds a different color to the design. Finishing treatments cause fabrics to resist wrinkling, creasing, or crushing. Special finishing treatments make possible what are known a s "durable press" or "permanent press" fabrics. Resin-type finishes are often used to add durable-press, flame-retardance, and water-repellency features. Resins are "set" into fabric during a curing operation that can be done before the fabric is converted into a n item such a s garments (pre-cure)or after the items are constructed (post-cure).Permanentpress resins that set permanent creases and pleats are best applied as a postcure operation. A summary of garment finishing methods is shown in Figure 6-17. Soil-release finishes may be either durable or nondurable. Nondurable soilrelease finishes applied in the washer are described in Chapter 5. The nondurable soil-release finishes coat the fibers and prevent soil penetration. This coating along with the soil is removed in the next laundering process.

Figure 6 1 7: Basic garment finishes for permanent press (Courtesy of Harry Cohen Assmiates) Flnishlng range

Garment manufacturer

Wash or dryclean.

PRESS

Pntcure

1

plant processing

press

LAUNDRY PROCEDURES

RATH

7

DRYING OVEN

Conventional postcunr BATH

Vapor phase

PAD BATH

&

Home wash 120' or dryclean

Low-temperature wash or dryclean

T

his chapter deals with all phases of laundry operations: soil separation and washer loading, processing steps, general formulas based on soil content, applying the general formulas to item classifications, and chemical handling in the washroom.

CHAMBER

Durable soil-release finishes are applied during fabric manufacturing. Durable finishes are either a soil-resistant or soil-release type. Soil-resistant finishes are designed to resist penetration by either waterbornestains or oilborne stains. Finishes that resist penetration by waterborne stains are very similar to water-repellant finishes and are usually based on silicone or fluorochemicals. Other fluorochemicals can be used to produce resistance to oilborne soils. Soil-release finishes function by attracting water and allowing the water to remove the soil. Acrylic-based soil-release finishes may increase the stiffness of the fabric.

PREWASH STEPS Soil sorting Textiles should be sorted according to soil classifications such as light, medium, and heavy because not all items require the same laundering process or intensity. Proper soil sorting allows the load to be matched to the best formula for soil removal, resulting in the most economical use of chemicals, water, and enerav. -Proper sorting also reduces textile damage and extends the life cycle for lightly soiled items, which otherwise would be exposed to excessively intense laundering procedures. Hotel and motel sheets, for example, require less laundering supplies, water, time, and energy for processing than do kitchen and bar towels. Pillowcases usually require heavier laundering procedures than do sheets from the same hotel or motel to remove hair and body oils, lipstick and cosmetic stains. The finishing method also governs how textiles are sorted. Laundry operators should separate items to be fully dried from items to be conditioned. Items to be finished on different types of equipment, a t different speeds on the same equipment, or with different crewing on the same equipment need to be sorted. Fiber content also influences soil sorting. Polyester/cotton blends should be separated from cotton items. Polyester blends must be handled differently from cotton because the thermoplastic nature of polyester requires lighter load weights, gradual cooling during rinsing, and very light extraction. Items of 100 percent polyester should be separated from polyester/cotton blends. Polyester/cotton blends require more extraction than does 100 percent polyester to remove the moisture held by the fabric. The system of soil classification by item suggested in Table 7-1allows for differences in individual plants and is widely used.

Table 7-1: Soil classification by item Item

Vew ligk

Light

Medlum

Hecnry

Vey hecnry

shop towels

Hotel/motel Sheets Pillowcases Bath towels, mats Heatthcare Spreads Hospital linen Operating room linen Pediatrics Nursing home linen General linen supply Barber towels Hair cloths Continuous towels Dental/doctor towels Hand towels Massage towels Roller towels Diapers

w/o Dehairing

Dehairing

Food sewice Table tops Napkins Colored table linen Garments Aprons Kitchen/bor towels Indudrial Garments

Dust control Entrance mats Sweeping cloths Dust mops Wet mops W~pingcloths Printer wipers Shop towels

Guidelines for loading

Washer loading is expressed a s pounds of fabric per cubic foot of cylinder volume. Loading: varies with fabric and machine type; affects soil removal, fabric strength, and, in certain fabric types, the tendency of blended fabrics to wrinkle; and influences the costs for chemicals, water, and energy.

The weight of water and soil in soiled fabric can vary from almost none to a sizable percentage of the fabric weight. In order to provide consistent standards, loading factors normally are based on the weight of clean, dry fabric processed. Load sizes have increased over the years. In the 1930s, commercial laundry practice in the U.S. was to load wooden washers a t about 3 pounds per cubic foot and metal washers a t about 4.5 pounds per cubic foot. British Launderers Research Association standards in 1945 specified 3.5 pounds per cubic foot loading for cottons. Following World War 11, load sizes began increasing. In the 1960s, it became virtually universal practice to load a 42- by 84-inch washer a t 350 pounds, corresponding to a load capacity of 5.2 pounds per cubic foot. Larger diameter washers permit somewhat higher loading factors. Tunnel washers have a load range from about 1.2 to 1.9pounds per cubic foot of compartment volume. The volume in cubic feet of a washing cylinder can be computed from Equation 7-1: Equation 7-1: v = d2z/2200 Where: v = volume in cubic feet d = diameter in inches z = length in inches

Overloading leads to poor laundering performance. Supplies can't be distributed properly throughout the load, and the tightly packed condition of the textiles impedes dilution, lowers soil removal, and results in poor mechanical action. Additional rinses may be required to remove loose soil and supplies remaining in the load; or frequently, loads must be rewashed. Underloading also can result in poor performance due to less mechanical action and can lead to excessive costs if water levels and chemical concentrations are not adjusted accordingly. Some fabrics must be underloaded because of their bulk a s compared to their weight. Garments containing polyester blends.usually are loaded a t 65 to 85 percent of calculated capacity to minimize wrinkling and provide easier subsequent finishing. Loading figures should be based on equivalent clean, dry textile weight. Operators who want to load on the basis of soiled weight must use a reliablesystem for converting clean, dry weight to soiled weight for each individual plant classification. Data collected in the plant is used to determine the ratio of soiled to clean weight to establish proper load sizes. Approximate figures for these ratios are given in Table 7-2. To use Table 7-2, multiply the weight of the textiles desired on a clean, dry weight basis by the ratio forthat item given in the table. The resultingfigure is the weight of soiled textiles that corresponds to the required weight of clean textiles. For example, if a washer has a rated capacity of 350 pounds of textiles on a clean weight basis and the load consists of bib aprons, then 350 pounds x

Brecrk

Table 7-2: Ratio of soiled to clean weight for various textile classifications (examples only)

m o : Soiled weight Ifem

Sheets, pillowcases. continuous towels. hand towels, family work Table linen Bib aprons Garments Kitchen and bar towels Infant diapers Shop towels (industrials)

Clean weight 1.O 1.O 1.15 1.0 up 1.3 1.45 1.5 up

1.15 = 402.5 pounds or approximately 400 pounds of soiled aprons is the correct load size. The figures i n Table 7-2 are merely guidelines; the ratios will vary with individual plant conditions. Consequently, each plant must determine these ratios by weighing soiled loads and comparing the soiled weight to the clean weight for the same load after processing. If proper soil sorting is practiced, the ratio of soiled weight to clean weight should be consistent and will need to be determined only pericdically. Counting is another method of sizing washer loads. Operators determine the number of clean, dry aprons, towels, garments, or other items needed for a proper load size and make up soil loads by counting out that number of items kach time.

WASH STEPS Flushes

The word "flush" is used to describe a fairly quick, high-level bath prior to the break or the bleach bath. (The word "rinse" is usually reserved for high-level baths following the bleach bath.) Flushes generally are used to condition textiles before subsequent baths and to remove debris and loose soil. Hospital work is sometimes given a n opening flush or flushes a t a low temperature-below llO°F-so a s not to set blood a n d albuminous stains (blood, serum, and many proteinaceous stains are set a t temperatures above llO°F). Many operators also add some alkali to this initial flush to prevent setting of blood stains. This reasoning is valid only if the alkali is distributed throughout the load before blood stains are set; however, some alkali or a surfactant in a low-temperature flush can be beneficial in removing blood stains. Flushes also are used to: W raise washing temperatures from low to high, lower temperatures from high to low, Ilower alkalinity prior to bleaching, W lower the soil concentration, and more. Other special applications of flushes are discussed in the formula section starting on page 98.

The word "break" is used to describe the first wash-chemical bath. In light- and medium-soil formulas, all of the surfactant and alkali to be used i n the entire formula generally is added to the washer in the break bath. The break is the single most important step in the laundering process from the standpoint of soil removal. It is a crucial checkpoint for chemical control. For optimum soil removal in medium-soil classifications, the total sodium oxide content of the break solution must be between 500 and 1,000 ppm. For heavier soil classifications, higher concentrations of sodium oxide are required. For surfactant-based products, the surfactant, not the alkali, h a s the major cleaning role, which means that high alkali concentrations may not be necessary. The break bath is monitored by titrating with phenolphthalein to measure active alkalinity. The total or methyl-orange alkalinity also may be measured by titration. Titration procedures are explained in Chapter 1. Some alkalies have much of their titration value below the phenolphthalein limit; for example, 50 percent of the titratable alkalinity of sodium carbonate (soda ash) lies above pH 8.3, with the remainder lying below this value. Alkali that titrates below pH 8.3 is considered inactive. In general, most of the alkalinity of the silicated alkalies (sodium metasilicate, sodium sesquisilicate, and sodium orthosilicate) is available above pH 8.3. Suds and carryover suds

Any number of suds and flush baths may occur between the break and bleach baths, depending on the nature and intensity of the load's soil content. Suds baths are carried out a t low water levels, usually with hot or tempered water. The temperature of the water is thermostatically controlled. Suds baths are referred to a s carryover suds; no alkali or detergent is added. Their function is to: Iincrease soil removal by lengthening thecontact time between alkali/detergent and fabrics a t a n elevated temperature, Ilower the soil content of the water in the washer and textiles prior to bleaching, and W reduce pH and total alkalinity to the level a t which bleaching can be carried out most effectively. Bleach suds

The bleach suds bath is the last point a t which detergency-promoting agents are added to the laundry formula. In the past, this step has been referred to a s the "bleach suds" because a light, running suds was the visual indicator that the pH was correct. But the advent of low-sudsingsynthetic detergents and the practice of adding flushes between brcak and bleach to lower alkalinity have made pH testing a necessity to determine that the pH is correct for bleaching. The key measurement of the bleach bath is pH, although titration values can also have meaning, especially when the chemical composition of the alkali is known. The pH of the bleach bath a t 150°F should fall within 10.2 to 10.8 for chlorine bleach. A pH below 10.2 results in accelerated bleach action, with its

accompanying fabric damage, while a pH above 10.8retards bleaching action, which lessens stain removal and causes trailing of unspent bleach into the subsequent bath. Bleach pH values may be lower provided water temperatures are also lower. Rinsing Rinsing i s the term used for baths following the bleach and preceding the sour or finishing bath. Duringrinsing the final portions of loosened soil are removed along with the bulk of the washing compounds used in laundering. The temperature of the - be . removed . load also is gradually reduced to the point a t which textiles can .from the washer. ~ i i s e are s always carried out a t a high water level and usually with no additional chemicals except for antichlors. The number of baths required to complete the washing cycle is determined by the amount of dilution needed to remove the soil and lower the alkalinity and chlorine content. Titration measurements help determine the proper number of rinses. The following paragraphs deal with the controllable factors in rinsing, which have a bearing on the minimum rinsing requirements. Tem~erature.Rinsing lowers temperature a s well a s soil content, alkalinity, and chlorine content. . Usuallv the temperature of the wash load is between 130' and 150°F.when the bleaclh bath is dumped. The optimum temperature for handling a wash load with bare hands is in the range of 95' to 105OF.This means that rinsing reduces temperature by about 35 to 45 degrees if the load will be removed by hand (pulled). If the washroom has self-dumping equipment or washer/extractors, the linen can be dumped from the equipment at 130' to 140°F. Number of rinse baths. The function of the rinse baths is to remove loosened soil (most of which has been eliminatedprior to the bleach step) and the -chemicals used in laundering (alkali, detergent, and bleach). All of the chemicals are highly soluble and are easily removed a t a water temperature of from 110° to 140°F. The best way to check rinsing adequacy or completeness is to titrate for the amount of residual alkalinity. Each rinse must be titrated and compared with that of the tap or softened water being used in the rinse. This procedure is described in detail in Chapter 1.The final rinse titration should be in the range of 50 to 125 pprn bicarbonate above the tap-water titration. For many years, experts said that the differential should not exceed 50 pprn bicarbonate. This was true when all-cotton textiles, which are highly sensitive to yellowing from alkaline scorch in tumblers and on presses, constituted 95 to 99 percent of the fabrics used by textile rental operators. However, currently a 125 pprn bicarbonate differential between tap and the last rinse is sometimes acceptable because of the increased use of polyester/cotton textiles and fabric brighteners in many laundering supplies, a s well a s the need to conserve water and heat. If titration shows that alkalinity is reduced sufficiently, usually the other laundry chemicals are reduced enough for the textiles to proceed to souring and finishing. -

It is good practice to check for residual chlorine bleach in the last rinse by adding a few drops of a 0.1 percent solution of orthotolidine reagent as described in Chapter 1.The reagent can be added to a sample of the rinse solution or can be dropped onto the fabric itself. If fabric is used, it must be thoroughly rinsed and rewashed. A yellow color indicates the presence of chlorine. However, tap and softened waters used in rinsing also may contain sufficient available chlorine to be detected with orthotolidine reagent, plus some water impurities may produce false-positive results. Dilution. Rinsing also accomplishes dilution, a key function in the overall washing process. The degree of dilution depends on the type of fabric being processed and whether high or low water levels are used. Cotton retains more water than polyester. The cost of water has risen dramatically in recent years, a s have the costs of softening, heating, and disposing of it. For these reasons, less rinsing is done today than was thought necessary in past years. A minimum of four rinses, two hot and two split, was the rule a generation ago. Today, three rinses or two rinses and a n intermediate extraction are common. The following mathematical model illustrates the magnitude of dilution in a rinsing process. Under ideal conditions, the amount of soil remaining after any number of baths in a washer can be calculated a s shown in Equation 7-2.

Equation 7-2 :

s, = % (VfNtY Where: x = number of baths S, = concentration of soil after x baths Si = amount of soil present before washing/rinsing begins Vf= amount of water held by the fabric after draining Vt = total amount of water to achieve the set water level with the washer loaded (includes Vf)

Assume the titration of the bleach bath is three drops 1.0 N (N/l) acid. This alkalinity is expressed a s a concentration of 186 pprn sodium oxide (Si)A 42-by 84-inch washer loaded with 350 pounds of cotton fabric will retain 105 gallons of water (Vf) after draining. To reach a 12-inch rinse level requires an additional 116 gallons of water, producing a total rinse water volume of 221 gallons (Vt=Vf+ water to produce 12-inchlevel or 221 = 105 116). Equation 7-2 is applied below to show the dilution of the concentration of 186 pprn sodium oxide.

+

Concentration after first rinse: (SI) = 186 pprn (105/221)' = 186 (.475) = 88 pprn Concentration after second rinse: (52) = 186 pprn (105/221)2 = 186 (.475)" = 186 (.226) = 42 pprn concentration after third rinse: (S3) = 186 pprn (105/221 )3 = 186 (.475)3 = 186 (.107) = 20 pprn

The chemical concentration after the third rinse is approximately equivalent to three drops of N/1 acid. This rinse bath would consume a total of 348 gallons (116 gallons for each of three rinses), which is considered adequate rinsing by current standards.

Different concentrations are obtained for 50/50 polyester cotton, which holds about 55 percent as much water as cotton after draining (Vf= 58 gallons). To reach a 12-inch rinse level, a rinse volume of 174 gallons (Vt) is needed. Concentrationafter first rinse: (Si) = 186 (581174)' = 186 (.333) = 62 pprn concentrationafter second rinse:( S 2 ) = 186(58/1 74)2= 186(.333)== 186(.111)= 21 pprn

To achieve the same dilution effect on poly/cotton a s with all cotton (20 pprn or three drops of N/10), only two rinses consuming a total of 232 gallons [2 x (174-58)]of water are needed since poly/cotton rinses more rapidly than 100 percent cotton and requires fewer rinses. Another factor t h a t governs the number of rinses needed is the type of equipment used. Washer/extractors allow an intermediate extract. One of the rinses may be followed by 30 to 60 seconds of extraction, which spins off some of the water from the textiles, reducing soil, alkali, detergent, and bleach content, and allowing the machine to take on more water on the subsequent filling. In the cotton example, the dilution produced by following the first rinse with an intermediate extraction is increased because Vf is reduced to 53 gallons from 105 and an additional 168gallons (instead of 116) must be added to achievethe 12-inch rinse level: Concentration after first rinse and intermediate extract: (S,) = 186 p p r n (53/221) = 45 pprn concentration after second rinse: (S2) = 45 pprn (1051221) = 21 pprn

The total water consumed is 116 gallons to fill the first rinse plus 168 gallons to fill the second rinse for a total of 284 gallons. A general guideline is that the dilution effect of a n intermediate extraction is equivalent to one rinse. This procedure is particularly suited to loads containing all-cotton goods. With one less rinse operation, water savings result despite the fact that the water removed during extraction must be replaced on the next fill to reach the desired rinse level. I n the cotton example, two rinses and a n intermediate extraction using 284 gallons of water yield the same dilution effect a s the 348 gallons needed for three rinses and no intermediate extraction. The actual production time may be the same for both procedures because some machines require additional time to start and stop a n intermediate extraction. Antichlors. Antichlors are added to rinses to help remove residual chlorine. They are generally added to the first or second rinse following the bleach and also may be combined in the sour bath. Common antichlors are sodium bisulfite, sodium thiosulfate, or proprietary products; usage is usually a t the rate of 0.5 to 2.0 ounces per 100 pounds of textiles. Antichlors can help conserve water by reducing thenumber of rinses. They're often added if there is danger t h a t fabrics will retain available chlorine even though the rinse water sampled a t the dump shows n6 residual chlorine present. For example, certain resin finishes such a s some permanent-press finishes are chlorine-retentive. This is why antichlors usually are added if chlorine bleach is used in laundering resin-finished garments. Sour bath Souring is normally the final step in the launderingprocess. The purpose of the 96

sour or acid bath is to neutralize the alkalinity of the water in the textiles before finishing. The function of the sour and its role in the process have been described in Chapter 5. Souring is done a t a low water level, generally a t the temperature desired for extracting and finishing the textiles. Higher souring temperatures improve extraction and reduce drying time. Souring time varies depending upon conditions. In this bath, other finishing supplies such a s fabric softeners, antibacterial agents, brighteners-even starch-may be added along with the sour. Starch use general1y requires lengthening the bath time. Proper souring is determined by monitoring the pH ofthe finished work. This can be done in two ways: The pH of the sour solution can be checked in the same way described for the bleach bath, using a pH meter, slide colorimeter, or pH papers on a sample of sour bath. By far the most commonly used technique is to drop Universal Indicator onto an item in the washer. Universal Indicator is a pH-sensitive formulation of dyestuffs that indicates pH by color. Recommended souring guidelines are given in Table 7-3. Table 7-3: Sour guidelines* sour color

pH range

lndlcafes

Bluegreen to blue Green Yellow Orange Red

above 7.5 6.5-7.5 6.0-6.5 5.5-6.0 4.5-5.5

Not soured OK for flatwork Mid-range OK for towels OK for diapers

'Using Universal Indicator as supplied in the TRSA Washroom Test Kit. Extraction

Extraction is used to lower moisture. Laundering begins by saturating the textiles; no free water will accumulate in the cylinder until the textiles have first absorbed water up to the saturation point. For cotton, this is approximately 0.3 gallons per pound or 2.5 pounds of water per pound of cotton. For 100 percent polyester, the waterretained between the fibers is about 0.1 gallons per pound or 0.8 pounds of water per pound of polyester. Thus, a 350-pound load of cotton will hold about 105 gallons (875 pounds) of water when saturated. A 350-pound load of polyester will hold approximately 35 gallons (292 pounds). The water consumption of laundering formulas is determined by adding the amount of water required for saturation to the amount of free water in the washing cylinders. Extraction reduces water content in textiles to 25 to 70 percent moisture retention, depending on the type of fabric and equipment. Moisture retention is a n expression of the ratio of the weight of the retained moisture to the weight of the clean, dry textile. Clean, dry weight is most consistently determined in the plant by weighing textiles after full drying. A pound of cotton textile holds 0.3 gallons of water (2.5 pounds) or 250 percent of the dry weight.

Extraction reduces retained moisture to 50 percent, removing two pounds of water per pound of fabric. Since 50/50 polyester/cotton retains only 1.7 pounds of water per pound of fabric, only 1.2 pounds mut be removed to reach the 50percent moisture-retention level. However, polyester/cotton textiles come out drier than cotton for the same extraction effort. Extraction takes place automatically in washer/extractors; controls shift the washer into high-speed rotation following the laundering cycle. With conventional and tunnel washers, however, the work must be removed from the washer and loaded into a separate extractor. There are two types of extractors: centrifugal and hydraulic. In centrifugal extraction, the centrifugal force spins the water out of the fabric. I n one type of hydraulic extractor, the water is squeezed from fabrics by means of fluid pressure exerted against a flexible diaphragm i n which the textiles rest. I n another type of hydraulic extractor, fabrics are placed between a piston and a bulkhead. The piston is forced toward the bulkhead, thus squeezing water from the textiles. A hydraulic press is usually used with tunnel washers. Each method of extraction h a s advantages a n d disadvantages, but regardless, extraction is a more cost-effective method of removing water than dryers, ironers, and presses. The extraction process is most efficient a t high temperatures and if fiber lub-ricants - - -- ..- such a s fabric softeners have been added to the sour bath. In general, the warmer the fabric extracted, the better the moisture removal. -

GENERAL LAUNDRY FORMULAS Sorting by soil content and item classification h a s been described earlier in this chapter. In this section, basic formulas are described for five levels of soil content: Ivery light soil, Ilight soil, Imedium soil, Iheavy soil, Ivery heavy soil. Beginning 104 of this chapter, these formulas are applied to the - on page com&on item' classifications listed in Table 7-1: Ihotel/motel, Ihealthcare, Igeneral linen supply, including food service a n d other items, Iindustrial garments, dust control, and Iwiping cloths. The last three classifications-industrial, dust control, and wiping towelsvary enough from the general soil-content formulas to warrant specific formulas of their own. For each formula, supply usage i s based on pH and titration values. Measuring and closely controlling pH is essential for bleaching and souring baths; titrations normally are confined to sudsing and rinsing baths. Procedures for

these measurements are outlined in Chapter 1. Titrations for active and total alkalinity are conducted using phenolphthalein and methyl orange indicators, respectively. The relationship between the phenolphthalein (active alkali) and methyl orange (total alkali) endpoints depends on the chemical constitution of the alkali, that is, the ratio of active and total alkali, a s described in Chapter 1. Early research on removing soil from fabric pointed to a distinct correlation between the efficiency of particulate soil removal and the amount of sodium oxide (Na20) contained in the detergent solutions. Based on their findings, washroom chemists suggest maintaining total alkalinity (Na20)limits a t 250 to 500 ppm for light soil, 500 to 1,000 ppm for medium soil, and 1,250 to 3,000 ppm for heavy and extra-heavy soil. These guidelines are not appropriate for surfactant-based products that rely on the surfactant content rather t h a n alkaline content for cleaning. For these products, titrations are used only to measure detergent concentration. Appropriate titrations vary from product to product. The following formulas represent guidelines based on many years of research a n d in-plant experience. They may be used a s written for alkaline products or modified to suit the characteristics of soil classification, type of washer, or other variables in a n y given laundry. The authors, task force committee, and publishers present these formulas a s procedures for producing clean textile products a t reasonable consumption levels of water, energy, and chemicals. No consideration h a s been given to modifications t h a t may be necessary to meet wastewater requirements or to protect laundry workers from exposure to hazardous soils. Each operator is responsible for ensuring that plant procedures are in compliance with all environmental and safety requirements. Operators must obtain Material Safety Data Sheets (MSDS) from customers for hazardous soils that are likely to be on the soiled textiles a n d consult with water treatment facilities and other appropriate agencies to ensure all procedures are in compliance.

Very light soil Table 7-4 is a formula for very lightly soiled items such a s hotel sheets. The formula suggested here i s a one-suds procedure with a six- to eighbminute break suds. One quart of 1.0 percent chlorine bleach per 100 pounds of textiles is included along with alkali and detergent. This is followed by two rinses using tempered water to cool t h e load to the desired finishing temperature. The sour bath, which may include fabric softener, antibacterial agent, antichlor, and brightener, follows rinsing. If the hot water tank i s set a t about 165OF,expect a break temperature of l3s0 to 145OF, which is well within the limits for proper use of bleach. Light soil

The formula for light soil in Table 7-5 is a two-suds procedure with t w o five- to seven-minute steps followed by three rinses and a sour. Formulas for very light soil and light soil differ in two ways: IVery-light-soilforn~ulasadd bleach to the break; in the light-soil formula, the bleach step follows the break. 99

Table 7 6 : Very-light-soil formula

Operatlon

Water level

Temperature Tlme (OF) (min.)

Break suds

Low

135-145

6-8

Alkali, swp/ detergent, bleach Antichlor

Rinse

Hiah

120-130

1-2

Rinse

Hiah

-

105-115

1-2

Finish

LOW

105-115

4-6

Supply type

Supply usage PH

Titratlon

9.8 60 to 180 pprn to Na,O ( I to 3 10.8 drops N/l with phenolphthalein)

50 to 120 ppm HCOj (4 to 10 drops N/10 with methyl orange) over tap Sour. softener. 5.5 bacteriostat to 7.0

Table 7-5: Light-soil formula

The light-soil formula calls for three rinses, whereas only two are suggested in the very-light-soil formula. The break titration for the light-soil sequence is higher t h a n for very light soil because the light-soil formula requires more alkali a t the break t h a n does the very-light-soil formula. Because time and washing compounds increase, detergency increases with the light-soil formula. Preliminary flushing is used for blood and albuminous stains. When there are no blood stains, the formula can begin with the break suds bath. Medium soil Table 7-6 i s a medium-soil formula t h a t provides for a break suds of six to eight minutes, a suds or carryover of a somewhat shorter time, and a bleach bath of six to eight minutes. This is followed by the same rinsing pattern shown for light soil. The formula extends the cleansing action by adding a suds between the break suds a n d bleach. This step is now referred to a s a carryover rather than a suds because in many instances no supplies are added. The carryover becomes just that, a renewal of water a t a low level which serves to lengthen the time of contact between textiles and washing solution a t a n elevated temperature.

Table 76: Medium-soil formula

Operation

Water level

Temperature Time (OF) (min.)

Flush

High

100-110

2-5

Flush

High

135-145

1-2

Break suds

Low

135-145

5-7

Supply usage

Supply

type

Alkali, soap/ detergent

Bleach

LOW

135-145

5-7

Bleach

Rinse

High

120-140

1-2

Antichlor

Rinse

High

105-115

1-2

Rinse

High

105-115

1-2

Finish

Low

105-115

4-6

PH

Titration

10.5 250-375 pprn to Na,O (4 to 6 11.5 drops N/l with phenolphthalein) 9.8 to 10.8

50 to 120 pprn HCOj (4 to 10 drops N/10 with methyl orange) Sour, softener. 5.5 bacteriostat to 7.0

Operation

Water level

Temperature Time (OF) (min.)

Supply type

Break suds

Low

140-150

6-8

Alkali, soap/ detergent

Carryover or (suds)

Low

135-145

4-6

(Soap/ detergent)

Bleach

Low

135-145

6-8

Bleach

Rinse

Hiah

120-130

1-2

Antichlor

Rinse

High

105-115

1-2

Rinse

High

105-115

1-2

Finish

Low

105-115

4-6

PH

Supply usage Tllratlon

11.0 500-900 pprn to NapO(8 to 15 12.0 drops N/l with phenolphthalein)

9.8 to 10.8

-

50 to 120 ppm HCOj (4 to 10 drops N/10 with methyl orange) over tap Sour, softener, 5.5 bacteriostat to 7.0

Heavy soil This classification represents a departure from previous formulas. Heavy soil removal requires a high water temperature, 165' to 180°F, and greater alkalinity than for medium soil. To remove the added alkali, the formula calls for a flush or flushes following the carryover. The flushing reduces bleach bath pH below 10.8, assuring proper bleaching. Another significant difference is t h a t the time devoted to the break a n d bleach baths is longer t h a n in previous formulas. For proper cleansing action, soil and stain levels in this classification need longer contact with laundering solutions.

Table 7-8: Very-heavy-soil formula

Table 7-7: Heavysoil formula

Operation

Water level

Temperdun, Tlme (OF) (mln.)

Flush'

High

100-110

25

Flush

Hiah -

140-160

1-2

Break suds

Low

165-180

10-12

Carryover or (suds)

Low

Flush

High

165-180 140-160

10-12

Alkali, soap/ deteraent "

135-145

8-10

Bleach

Rinse

H~gh

120-130

1-2

Antichlor

R~nse

H~gh

105-115

1-2

R~nse

High

105-115

1-2

Low

105-115

4-6

Temperature Tlme (OF) Win.)

Flush'

High

100-110

2-5

11.5 1,250-1.550 ppm to Na,O (20 to 25 12.5 dr&s N/I with phenolphthalein)

Supply usage

Supply

tVpe

Flush

High

140-160

1-2

Break suds

Low

165-180

15-20

Alkal~.soap/ detergent

Break suds

Low

165-180

10-12

Alkali. soap/ detergent

Suds

LOW

165-180

5-8

h p / detergent

Tltrdon

Flush

High

140-160

1-2

Flush

High

140-160

1-2

Bleach

Low

135-145

8-10

Bleach

Rinse

High

120-140

1-2

Antichlor

Rinse

High

105-115

1-2

Rinse

High

105-115

1-2

Finish

Low

105-115

4-6

pH

Thotion

11.8 1,800-2.150 ppm to Na,O (30 to 35 12.6 drops N/l with phenolphthalein) 11.5 1.250-1.550 ppm to Na,O (20 to 25 12.5 drops N/l with phenolphthalein)

9.8 to 10.8 ~

1-2

Low

Finish

pH

(Soap/ detergent)

Bleach

Water level

Supply usage

Supply

type

Operation

9.8 to 10.8

50 to 120 ppm HCO; (4 to 10 drops N/10 with methyl orange) over tap Sour, softener, 5.5 mildistat to 7.0

'An opening low-temperatureflush is used topreventsetting food stains that might bepresent in this classification.

Very heavy soil This formula is similar to the one for heavy soil except that it includes two hightemperature breaks, each with alkali and soap or detergent. Both breaks run for longer periods of time than in the heavy-soil formula.

I

~~

50 to 120 ppm HCOj (4 to 10 drops N/10 with methyl orange) over tap Sour, softener, 5.5 mildistat, to antichlor 6.5

'Anopening low-temperatureflush is used topreventsetting foodstains that might bepresent in this classification.

If using soap on this soil classification, alkalinity levels must be closely controlled to prevent laundered textiles from being soap-specked. This occurs when the acid content of greasy soils is so great t h a t i t converts the soap to free fatty acid, which results in soap specks. Increasing the alkali content stops this process. Some operators deal with this problem by using only a nonionic synthetic detergent for very heavy soil or by using anonionic detergent on the first break, followed by alkali and soap on the second break and carryover. Bleach recommendations for this soil classification range from two to three

quarts per 100 pounds of textiles. While the authors traditionally have held to a n upper limit of two quarts of 1.0 percent bleach per 100 pounds, they recognize that the stain removal achieved a t three quarts may reduce rewash to such a n extent that the higher level is justified. The additional bleach isn't used for added whiteness but for stain removal. The effects of bleach usage above two quarts of 1.0 percent bleach per 100 pounds are tested by running test pieces a t two- and three-quart mixtures and assessing the rewash percentages a t each level. Increasing bleach usage above two quarts of 1.0 percent bleach per 100 pounds-long recognized a s the upper limit-will most certainly increase tensile strength loss. This factor must be included when considering the cost of such a n increase. The elevated tensile strength loss must be balanced against the amount of rewash a t a lower bleach level. With the exception of light a n d very light soil, all laundering formulas are identical from the bleach bath onward. This is because the washer contents reach the same alkalinity and soil content levels a t the bleach bath, no matter what the soil level is. I t follows, then, t h a t each classification requires the same rinsing,

ITEM CLASSIFICATIONS Hotel/motel

This classification is the lightest soil encounteredin the textile rental industry. With few exceptions, it's one-day soil and presents minor problems. Usually, the very-light-soil formula shown in Table 7-4 is sufficient, although some plants often classify pillowcases a s slightly heavier soil than sheets. Similarly, bath towels, mats, and washcloths may or may not be classified on the same soil level a s sheets. In general, these items are very lightly soiled, with stains confined almost entirely to cosmetics. The souring step on sheets a n d pillowcases is very important. These items are usually finished on high-speed equipment such a s flatwork ironers and folders and must be soured to a pH of about 6.5 to 7.0 to enhance fiber lubrication and promote peak ironer speeds. Fabric softeners also increase fiber lubrication and aid in ironing. Bath towels are washed separately and should be soured down to a pH of 5.5 to 6.0 to reduce a n y tendency to yellow in tumbler drying. Healthcare

Healthcare items include hospital, clinic, and nursing home linens, which are further broken down into ward, operating room, and incontinence care linens. Ward linen is classified a s either light or medium soil, depending on the quality requirements or care in sorting a t the institution or in the plant. Operating room linens may be classified a s light or medium soil. Pediatrics work usually i s classified a s medium soil because of the stains in baby clothes from medication and formula food stains. Nursing home linens are generally classified a s medium soil-occasionally heavy soil - depending on housekeeping practices a n d the quality of care in individual institutions. Incontinence pads and adult diapers are always processed separately, nor-

mally a s medium soil with extra initial flushes and extra rinses to remove urine odor and feces. I n f a n t a n d a d u l t d i a p e r s . Infant and adult diapers and pads used in a n institution are laundered frequently enough to keep stains from aging to t h e point where heavier soil formulas are needed. On the other hand, infant diapers served by professional diaper services become heavily stained because diaper services operate almost exclusively on weekly service, allowing stains to age to a point that requires a heavy-soil formula. Adult incontinence pads and diapers are complex assemblies of textiles containing filler fibers attached to a nonwoven backing. Since they're quite sensitive to the action of bleach and drying temperature, both processes must be carefully controlled to maximize the life of these items. G e t t i n g h e a l t h c a r e t e x t i l e s hygienically c l e a n . The professional laundry process is capable of producing hygienically clean linens. I t may also produce sterile linen, but sterility can be guaranteed only by autoclaving. Decades of work have been devoted to identifying laundry processes that destroy or remove microorganisms from textiles. Studies confirm t h a t a number of interrelated factors contribute to the amount of microorganisms removed from fabric: detergents, action of chlorine bleach, washing temperature, action of repeated changes of water (dilution), and drying temperature in dryers or on ironers and presses. Attempts have been made to rank the importance of each of these factors in eliminating bacterial contamination, but no definitive studies are known. Studies conducted a t the Pennsylvania State University in the 1930s reported t h a t a water temperature of 160°F destroyed all bacteria present on linen. Consequently, for years many states required t h a t healthcare linens be processed a t water temperatures of 160°F. Research studies carried out in hospital laundry plants in recent years have demonstrated that fabrics can be washed hygienically clean a t temperatures below 160°F, a s long a s suitable washroom chemicals (alkalies, detergents, bactericides, sours, etc.) are used, bleaching conditions are maintained, and repeated changes of water occur. In addition, linens must be finished over flatwork ironers or fully dried in tumblers. In fact, studies reported in 1984 revealed t h a t hospital linens processed a t temperatures a s low a s 71°F were a s hygienically clean a s those processed a t 160°F under the same conditions. The term "hygienically clean" h a s no precise definition but implies t h a t items are free of microorganisms in quantities capable of causing illness. One laboratory procedure widely used to evaluate the microbiological content of textiles involves culturing a four-inch-square section (103.2 square centimeters) of fabric and counting aerobic spores. An empirical rating system classifies results: Number of spores 0 to 5 6 t o 50 51 t o 1 0 0 100 to 200

Rating

100 95 90 85

This purely arbitrary rating reflects the character of the atmosphere in which the linen is processed and stored. Spores are bacteria that have encapsulated themselves for their self-preservation. They are not pathogens. Of course, the presence of a single bacterium results in a failed test, since this indicates the possible presence of pathogens. The need to control the spread of infection influences the design of plants processing healthcare linens. For example, plants may: maintain a physical separation between soiled and clean linens; Iuse washing equipment designed to load on the soil side and unload on the clean side; W have a n air-flow system t h a t moves air in the opposite direction from linen flow, minimizing the chance for lint- and dust-laden air to pick up microorganisms from soiled linen and transport them into clean linen areas. Stains in hospital textiles. Healthcare work is likely to generate more stain rejects t h a n general linen supply classifications because of the high staining potential of medicines coupled with a low-intensity washing formula. Stain reject percentages for general linen supply normally run two to four percent excluding table linen. Hospital stain rejects usually range from four to seven percent. Color transfer. Color transfer on healthcare linens occurs when hospital greens, blues, and whites are laundered together. The colors transfer from colored to white fabrics, producing a tinting on white. This tinting is permanent because polyester does not release color. Although dyed polyester fibers are fast to laundering, the migration of loose dye contained on new fabrics is sufficient to produce this tinting effect. This problem can be avoided by simply separating whites and colors.

Table 7-9: Industrial shirt formula

General linen supply General linen supply covers textile items such a s aprons, the many types of towels used in commerce and industry, table linens, and wearing apparel not soiled with mineral greases. (The "general linen supply" and "food service" items in Table 7-1.) The soil content of these items ranges from medium (white and colored table linen) to heavy (continuous towels a n d the many types of hand towels used in clubs and in dentists' and doctors' offices) to very heavy (aprons and kitchen and bar towels). These items primarily contain animal and vegetable greases that can either be saponified using alkalies or emulsified with surfactants. Refer to Tables 7-6 through 7-8 for appropriate washing formulas.

'Bleach is added here for white classifications.

Industrial garments Industrial garments are most frequently made of polyester/cotton blends. Cotton provides comfort while polyester offers strength and wrinkle resistance that can eliminate pressing. Poly/cotton garments are often simply placed on hangers and passed through a warm-air or steam cabinet, which relaxes the wrinkles. On the other hand, polyester can "remember" wrinkles, so it's important not to overload washers and set wrinkles. These wrinkles don't relax in the finishing cabinet

Operalion

Water level

Ternperdure Time (OF) (min.)

Supply iype

Break

Low

130-160

18

Alkali, surfactont. phosphate. CMC

Carryover

Lw

130-160

9

Suds'

LOW

130-160

9

Alkali. surfactont, phos~hate. CMC

Rinse

High

115-145

2

(Antichlor if bleach is used',

Rinse

High

100-125

2

Rinse

High

Cold-100

2

Sour

Low

Cold

4

Supply usage TMon pH 10.0 375 to 500 ppm to No20 (6 to 8 11.0 drops N / l with phenolphthalein)

- -

50 to 120 Darn HCO; (4 ~O'IO drops N/10 with methyl orange) over tap Sour

5.5 to 6.5

-

or tunnel. Industrial garments are usually heavily soiled with mineral soils and greases, and a few operators elect to dryclean them. Drycleaning prevents the problem of wrinkling, since solvent temperature a n d moisture levels are normally low a n d loading is light. Garments can be easily dried wrinkle-free. Also, the solvent h a s a powerful degreasing impact on the oily soil. The trade-off, however, is that water-soluble soils such a s perspiration and many food stains tend to accumulate and detract from the wearing quality of drycleaned garments. To solve this problem, some operators launder the garments every third or fourth cycle to keep water-soluble stains a t a minimum. Others use specially designed drycleaning machines capable of handling both water a n d solvent. Environmental concerns and regulations have affected the number of rental operators using drycleaning a s opposed to laundering. Washing formulas for industrial garments require certain modifications. Typical washing formulas for industrial shirts and pants are shown in Tables 7-9 and 7-10. The rinse temperature should decrease gradually in order to minimize the possibility of wrinkling due to thermal shock. Rinse-to-rinse temperature

Table 7-40: Industrial pants formula

Opercrtion

Water level

Temwroture Time (OF)' (min.)

Suppb lype

Break

Low

130-160

Alkali. surfactant. phosphate. CMC

18

Canyover

Low

130-160

9

Rinse

High

115-145

2

Rinse

High

100-125

2

Rinse

High

Cold-100

2

Sour

Low

Cold

4

-

Supply usage pH

Titration

10.0 375 to 500 ppm

to

Na20(6 to 8

11.0 drops N/l with phenolphthalein)

50 to 120 ppm HCO; (4 to 10 drops N/lO with methyl orange) wer top

5.5 Sour

to

6.5

decreases of about 15°Fare best until the solution reaches about 110°F. Pants are frequently loaded a t full capacity and shirts a t about 65 to 80 percent of full capacity if tunnel or cabinet finished (3..5 to 4.0 pounds per cubic foot) and 100 percent if pressed. Washing supplies used in industrial garment washing are different from those used in other fabric classifications for two reasons: High alkalinity, like high temperature, is harmful to polyester fiber, which predominates in industrial garment fabrics. Mineral greases must be emulsified since they aren't saponifiable by high alkalinity. Therefore, detergents designed for industrial garments contain mild alkalies; are high in complex phosphates; a n d are very rich in surfactants, which have a key role in penetrating a n d emulsifying mineral greases. Of course. all fabrics become soiled with body oils, especially wearing apparel a t cbllars and cuffs. Alkali is needed to clean the entire garment. Nonionic surfactants play a key role in industrial detergents, which may contain several different nonionics, making them effective in degreasing a s well a s in removing water-soluble soil. Another important ingredient in industrial formulations i s sodium carboxymethylcellulose (CMC), a cellulose derivative that promotes particulate soil suspension, minimizing soil redeposition. Therefore, a n effective industrial detergent will combine most of the following elements: a n alkali-usually low pH (less than 11.0), a complex phosphate-sodium tripolyphosphate or tetrasodium pyrophosphate,

a surfactant-usually nonionic or a blend of nonionics with other organic surfactants, carboxymethylcellulose, and fabric brightener. Bleach is used to removestains and maintain whiteness on whitework, such a s lab coats, smocks, and shirts. Bleach can pose problems, however. Industrial garments frequently are produced from resin-finished fabrics that provide wrinkle resistance and easy care. These resins may be chlorine retentive. This retained chlorine will cause permanent yellowing a n d degradation of the fabric if i t isn't neutralized. To counter this, antichlors (bleach neutralizers) are added to the rinses following bleaching. Using oxygen bleach i s a n alternative, although the bleaching action is milder t h a n sodium hypochlorite on some stains. Extraction, drying, a n d finishing of industrial garments must be carefully controlled to minimize wrinkling. Since polyester fiber absorbs virtually no water, extraction usually is minimal, ranging from merely bringing the basket up to speed to extracting for two, three, or four minutes. For compression-type extractors, lower pressures are used. Garments can be finished and dryed by pressing or by being passed through hot-air/steam cabinets or tunnels. Some operators tumble dry garments before using a cabinet or tunnel, while other plants pull the garments directly from the extractor and hang them wet for cabinet or tunnel finishing. The latter, obviously, requires a much longer time in the finishing system than do fabrics t h a t are fully dried. Wet-to-dry tunnel finishing produces a better flat finish than does dry-to-dry. While these finishing methods differ, the basic principle of dealing with a thermoplastic fiber such a s polyester is to ensure that wrinkles aren't set into the fabric during processing. Following these precautions will avoid wrinklesetting: Scale back load weights from normal machine standards. Minimize drain times between washer baths to avoid setting sleeve wrinkles. Reduce temperature gradually during rinsing. Minimize extraction. Finish garments by either pressing or drying in a cabinet or tunnel a s soon a s possible following extraction or full-drying. Do not overload hampers holding fabrics in process. Dust control

The term dust control refers to textiles used by industry for floor care: mats, dust mops, wet mops, dusting cloths, and sweeping cloths. Mats. Mats are widely used in shops and markets, restaurants, offices, and industrial plants. They can be constructed of anylon pile with rubber backing, cotton pile with rubber backing, cotton pile with latex backing, or polyester pile with vinyl backing. Mats are quite durable. By virtue of their chemical composition, the synthetic-pile types are relatively resistant to soil and moisture retention, although vinyl mats are quite sensitive to heat. Therefore, for best results, mats shouldn't be processed above 120°F.

Figure 7-1:Closed-oil mop washing system

Table 7-1I:Mat formula Suppty usage

Water operation

level

Temperature Tlme (OF) (min.)

Rush

High

110-120'

2

Rrwk

Hiah

110-120'

6-10

Carryover"

High

110-120'

6

Rinse"'

High

110-120

2

Rinse

High

Cold

2

Phenolphthalein

SUPP~~

bP Alkal~,soap/ detergent

PH

tthation

10.5 60 to 180 ppm to Na,O ( ?to 3 11.5 dro~sN/1'1"" . .,

'130-140°F for cotton pile mats "Only for heovily soiled cotton and nylon pile mats "'Two or more split rinses for heavily soiled cotton and nylon pile mats ""Up to 960ppm (16 drops N/1 acid using phenolphthalein indicator) for heovily soiled cotton and nylon pile mats

Mats can be processed in conventional equipment or, where volume warrants, in specially designed mat machines capable of processing 1,000 mats or more per day. Mat machines use a scrubbing and beating action and apply detergents and hot water jet sprays to loosen a n d remove soil. Some machines feed mats pile side down so that soil falls downward in the machine as it is loosened. Most plants process mats in conventional washers or washer/extractors. Mats are normally classified a s light soil, since little soil adheres to synthetic fiber. A typical wash formula for mats is shown in Table 7-11. Formulas may specify either tempered or split (hot a n d cold) water throughout. Two flushes instead of one will remove excess sand and clay. Mat formulas normally call for modest amounts of alkali and detergent. Entrance mats of 100 percent cotton pile require a much heavier wash formula than synthetic mats because they get much dirtier. Cotton mats larger than three by five feet may need to be treated or sprayed with flame-retardant substances per Federal regulations DOC-FF-1-70 a n d DOC-FF-2-70. Mops. Mops are a very significant part of dust control. Mops may be wet or dry, but by far the biggest part of this classification consists of oil-treated mops used dry on floors. They are constructed in such a way that they can be drawn over a metal holder attached to a handle to produce what is referred to in building maintenance a s a sweeping tool. Mops generally are made from cotton or blends of cotton with polyester or acrylic. The synthetic fiber significantly extends the life of the mop, but a n allsynthetic mop will not pick up soil. Acrylic is favored over polyester in blends with cotton because acrylic fiber picks up oil in the treatment process whereas polyester doesn't. Mops frequently are dyed for identification a s well a s for esthetic reasons.

They may be dyed permanently before being placed in service or with each processing a s a regular part of the maintenance program, a s is the practice with shop towels. Mops are processed using a shop-towel formula (Table 7-12)and some plants process both items in the same load when oil treatment isn't applied in the washer. The oil treatment i s applied either in the washer, a s stated, or in a separate process outside the washer and consists of specially formulated or chemically modified petroleum products that coat the fibers. Where volume warrants, mops may be processed in a closed-oil system, which consists of a washer connected in a closed loop with a pressure filter so that the treating fluid-generally aliphatic (straight-chain) hydrocarbon oilcirculates continuously from washer to filter and back a s shown in Figure 7-1. The filter generally is made up of a series of hoops or rings covered with fabric through which the hot oil is pumped. In appearance i t is much like a stack of dinner plates. The plates are coated with diatomaceous earth, which is added to the oil in the system. This system traps soil particles removed from the fabricin the washer, a n d the oil carriers them from the washer to the filter. The oil supply is heated to process temperature in a separate holding tank and added to the closed loop with each load. A typical washer/extractor requires about 1,000 gallons of oil and diatomaceous earth. The soil load then is processed with continuous flow and filtration for approximately 25 minutes a t a n oil temperature of 100' to 140°F. This is followed by five to seven minutes of extraction, leaving t h e mops a t 10 to 30 per-

Table 7-13: Printer towel formula'

Table 7-12: Shop towel formula' supply u=ge

Supply usage Operation

Water level

Tempercrhrre Time (OF) (min.)

1-2

Flush"

High

100 or less

1-2

Flush"

High

100 or less

1-2

Break suds

Low

165-180

12-20

Operutton

Wcrter level

Tempercrhrre Time (OF) (min.)

Flush"

High

140-160

Supply type

Phenolphthalein PH M o n

Flush"

High

140-160

1-2

Break suds

Low

165-180

12-20

Carryover

Low

165-180

5-8

Flush

High

160-170

1-2

Rinse

High

160-170

1-2

Break

Low

160-170

8-12

Rinse

High

160-170

1-2

Rinse

High

160-170

1-2

Rinse

High

120-140

1-2

Rinse

High

160-170

1-2

1-2

Rinse

High

160-170

1-2

Rinse

High

160-170

1-2

Rinse

High

160-170

1-2

Rinse

High

105-115

Alkali. detergent

Grater 2.000-3.1 00 ppm than Na,O (32 to 50 drops N i l ) 11.5

Supply

type

Alkali, detergent

Alkali, detergent

Dye"'

'Operatorsmust ensure thatprocessingproceduresfor this classificationcomply with environmental and worker safety regulations. "To avoid combustlon. cold-water flushes are required if laundering highly flammable loads. "'Dye is sometimes added on the break if time is available for leveling and setting. Common salt up to 20percent of fabric weight may be addedaffer the dye has been introduced.

cent oil retention (20 pounds of oil per 100 pounds of dry mops). Another type of mechanism called a rotary vacuum filter is becoming more widely used for mop processing. This filter uses a vacuum pump to suck the oil through the filter cake. A blade shaves off a thin layer of soil-filled diatomite with each rotation of the filter. This type of filter takes up only 20 percent of the space of the standard plate-and-frame pressure filter and uses 50 percent less diatomaceous earth. A mop oil additive containing a detergent to hold soluble soil in suspension and a bactericide to prevent odor in the reused oil is commonly added to the system a t the rate of 1.5 gallons per 100 gallons of oil. If processing damp mops, mop oil additive is a must. Shop and printer towel formulas

Table 7-12 is a suggested formula for laundering shop towels, which usually are heavily soiled with mineral grease. Mineral grease can't be saponified; it must be emulsified. Emulsification requires higher ratios of SiO, to Na,O than are contained in sodium orthosilicate, so sodium metasilicate is generally used for laundering shop towels. Nonionic synthetic surfactant is the preferred detergent for shop towels. Operators processing shop towels or printer towels must ensure plant compliance with wastewater restrictions. In addition, customers must be asked

Rinse

High

120-140

1-2

Rinse

High

105-115

1-2

PH

Phenolphthalein M o n

Greater 2.000-3.100 ppm than Na,O (32 to 50 11.5 drops N/1)

1,800-2.150 ppm Na,O (30 to 35 drops N i l )

Dye"'

'Operatorsmust ensure that processing procedures for thb classificationcomply with environmental and worker safety regulations. "To avoid combustion additional cold water flushesare required if laundering highly flammable Iwds. "'Dye is sometimes added on the break if time is available for leveling and setting. Common salt up to 20percent of fabric weight may be addedaffer the dye has been introduced.

about the possibility of hazardous materials in thesoiled shopor printertowels and provide the appropriate MSDSs. Solvents also may beused to remove soil from shop and printer towels. However, flammability, toxicity, and disposal problems must be considered when using solvents. The formula for shop towels generally calls for a long break suds bath (up to 20 minutes) a t a temperature of 160' to 190°F. A carryover and a t least three rinse baths, all above 160°F, continue to draw off the grease t h a t h a s been loosened and suspended by alkali, solvent, and detergent. This is followed by a t least two additional rinse baths, with a gradual temperature reduction down to the point a t which the load is pulled. The printer towel formula in Table 7-13includes two breaks and many rinses. Cold water flushes are essential if there is any possibility of the towels containing flammable soils. Some printers' solvents can cause explosions in standard washers if warm or hot water is added before the solvent is removed.

The effectiveness of the laundry formula is measured by a break titration or by testing the absorbency of the finished towels. One in-plant check for absorbency is the sink test. Ten towels are selected randomly from a load. Each towel is folded twice (like a handkerchief), rolled into a cylinder, a n d secured with a rubber band. Each towel is timed to determine how long it takes to sink completely beneath the surface of cold tap or softened water. T h e sinking time of the 10 towels is averaged; a n average sinking time of 60 seconds or less is acceptable. Some customers, however, m a y require better absorbency, which translates into a n average sinking time of 30 seconds or less. This test is not reliable if residual surfactants a r e present. More precise absorbency tests such a s hexane extractables can be performed by a testing laboratory.

Table 7-14: Chemical makeup of selected detergent powders Products

CHEMICAL SUPPLIES Dispensing methods

Washroom chemical supplies are purchased either a s dry powders in drums or bags, or a s liquids in drums a n d crocks. While dry powders have long been the staple of washrooms, the wide use of tunnel washers h a s led to a n increased use of automatic liquid supply systems. These "liquid" supplies can be purchased a s liquids or made by adding water to dry supplies. Chemicals a r e added to washers manually, semiautomatically, or automatically. Manual control, a s implied, means t h a t dry or liquid chemicals are added to washers by individuals who determine t h e correct quantities, usually using different sized scoops. I n semiautomatic washrooms, operators simply fill supply hoppers or receivers on t h e washer with powder or liquid products. T h e washer automatically calls for t h e supplies a t the right point in t h e cycle. The operator still m a y determine the quantities added. Fully automatic bulk chemical delivery systems automatically inject washing supplies from a central liquid source. These systems a r e the only method used to add supplies to tunnel washers. Washroom supplies for semiautomaticor completely automatic systems a r e stored in either permanently installed or portable tanks. Delivery lines are either rigid pipe or flexible tubing; black iron or stainless i s recommended for heated supplies. Measured quantities of supplies are injected into washers from containers that have been prefilled manually or electronically to a fixed volume, or by a timed flow of fluid from the central source. Positive displacement pumps of various designs are widely used with automatic equipment. The trend is toward automatingsupply delivery to washers usingmicroprocessors to meter supplies; display operation functions; a n d record loads processed, times of operation, a n d other statistical data.

CHEMICAL SELECTION While dry powders traditionally have dominated the market for washroom supplies, liquids have taken a n increasingly larger share a s the industry h a s moved to automatic supply delivery. As previously mentioned, these liquids can be made in the plant by dissolving powdered supplies in water or purchased a s liquids t h a t a r e used directly from drums a s supplied. Some operators purchase in bulk,taking full and partial tankwagon quantities into on-site t a n k s .

'

Component

A

B

C

D

E

F

G

Caustic soda Anhydroussodiummetasilicate Soda ash Sodium tripolyphosphate S ~ P Anionic surfactant Nonionic surfactant CMC Brightener Unidentifiable

-

-

15 30 15

-

42 44

14 32 23 8

-

75

25 40 13 11

50 38

82 10

-

-

-

-

-

17

-

-

-

8 6 2

-

-

-

10 2

6 1

+

-

8 -

12 2 +. 3

9 2

9 1

+

+

3

1

-

+

+

+

7

23

-

T

1

= present

Alkali can be purchased dry or a s a liquid. For t h e past 25 years, the most commonly used dry alkalines have been sodium orthosilicate a n d sodium metasilicate. Laundry chemical suppliers offer these basic chemicals under their own packaging labels or a s the generic product. Liquid alkali generally is purchased in bulk. Built detergents are available from virtually every chemical supplier in powder form. These products generally are complete detergents needing no supplements, but their chemical makeup varies depending on the supplier. These built detergents contain alkalies, detergents, phosphates, surfactants, CMC, a n d a brightener. All except one in Table 7-14 are based on a synthetic surfactant, with the nonionic type dominating. T h e alkali/surfactant ratio runs from about 5:l to 15:l. Table 7-14 suggests t h a t there is a limit to thecombinations from which built products can be formulated. This table provides excellent guidelines for plant owners who prefer to proportion and feed washers from basic chemicals. T h e common practice of determining how much of a built detergent to use by titrating alkalinity presumes t h a t the proportion of alkali to other components in Table 7-14 is correct. This m a y not always be the case. Thesedry powders are manufactured by spraying the liquid nonionic surfactant onto the dry ingredients. However, alkali's ability to absorb t h e liquid nonionic surfactant is limited, a n d to achieve the levels shown in Table 7-14, manufacturers usually must add soda a s h to facilitate absorption. Soda a s h i s a relatively mild alkali, a n d caustic soda is often added with soda ash in order to boost the pH of the finished material. I n liquid systems, chemical supplies usually are grouped by compatibility a n d dispensing point in the formula. Alkali normally i s kept separate from other supplies. Surfactant can be stored alone or, a s i s frequently done, combined with phosphate, CMC, a n d brightener. These formulations can be purchased ready to use or combined in the plant from individual components. T h e mixtures often must be agitated to keep components dispersed.

Tallow soap is added in its neutral or unbuilt form dry, from a stock solution, or purchased a s a built product. However, using tallow soap in a liquid system is complicated. The solution must be kept heated so that it will flow. Unless the solution is constantly circulated, the supply lines must be heated during the shift and drained a t the close of each operating day to prevent congealing. Finishing chemicals can be purchased in several forms and combinations. Dry sours and antichlors are available from all chemical suppliers. Specialty products such a s rust-removing sours and formulations containing sour and fabric softener or a softener and a bacteriostatic agent are widely used. Add to this the fact that these finishing agents usually contain a fabric brightener, and it becomes apparent that there are many products to choose from. For liquid systems, sour may becombined with a fabricsoftener and a bacteriostatic agent. This mixture also needs to be agitated, since softeners have some tendency to salt out or be thrown out of solution by the high ion activity of the sour. If antichlor is incorporated in the finish mix, the softener, bacteriostat, and antichlor can be combined, but the sour must be maintained separately since some sours-notably fluosilicic acid (nfs)-will drive sulfur dioxide out of the antichlor, producing noxious odors. A successful combination of sour, softener, bacteriostat, and antichlor can be made using ammonium silicofluoride a s the sour. Starch usually is maintained a s a separate supply, or it can be combined with polyvinyl alcohol or polyvinyl acetate for sizing polyester and its blends. While starch is most commonly added dry to the washer, it works best if first dispersed in water by cooking in a starch cooker. Formulating liquid alkali

Alkali stock solutions can be prepared by dissolving 100 pounds of dry silicated alkali in 100 gallons of stock solution. Each gallon of this solution will contain one pound of alkali. Equivalent solutions of sodium silicates can be prepared in the laundry by combining liquid caustic soda (50.0 percent NaOH or 38.8 percent Na,O) and liquid sodium silicate (8.9 percent Na,O, 28.7 percent SiO,; 1:3.22 Na,O:SiO,). These chemicals, common to many industries, can be purchased in tankwagon quantities and held underground or in the plant in storage tanks. However, they must be stored a t or above the temperatures shown in the following chart to keep them from solidifying. The properties of these materials are listed below: Liquid caustic soda Density, lb./gal. Percent Nan0 Percent SiOn Solidifcation temperature

Liquid sodium silicate (4:3.22)

12.76 38.8 0.0 52°F

Combined in the proper proportions, liquid caustic soda and sodium silicate produce alkaline silicates of any molecular ratio (k value, where k is the ratio of Na,O to SiO,) up to a maximum solution concentration of about 1.25 pounds per gallon.

Table 7-15: Liquid sodium silicate formulas -

k (ratio of Na20: S i 0 ~ )

Formula

Caustic (gallons')

Sillcafe (gallons')

7.2 11.6 13.7 15.9

14.7 9.7 73 4.8

-

-

1 (Sodium metasilicate) 2 (Sodium orthosilicate") 3(3 to 1") 5(5 t o l " )

NazO.Si02 2Na2OOSiO2 3Na200Si02 5Na200SiO~

'Figures are gallons of caustic soda and sodium silicate needed to produce 7OOpounds of alkali in 100 gallons of stock solution. "Liquid system provides solutions equal to the theoretical values obtained from anhydrous solids. Due to moisture in the "dry" solids, the liquid-produced systems are slightly more concentrated.

Table 7-15 shows examples of some alkaline silicate formulations. For example, combining 7.2 gallons of liquid caustic soda, 14.7 gallons of liquid sodium silicate, and enough water to bring the volume up to 100 gallons provides the same product a s one 100-pound bag of anhydrous sodium metasilicate (k=l) dissolved in 100 gallons of water. The results are the same, but combining- the generic liauids costs less. The proportions of each component necessary to produce 100 gallons ( a t a concentration of 1.0 pound of alkali per gallon of solution) of other k ratios (Na,O:SiO,) can be calculated using the following proportions: W gallons of sodium silicate = 1791 (62k 60) W gallons of caustic soda = (1252k - 376)/(62k 60) W enough water to provide a total volume of 100 gallons To take maximum advantage of this system, a laundry needs about 5,000 gallons of storage-tank capacity for each component to hold tankwagon quantities, and personnel who are knowledgeable in the safe handling and mixing of these types of chemicals. Potassium silicates also can be formulated. A whole range of potassium silicates are formed by combining liquid caustic potash with liquid potassium silicate. There are three distinct advantages to using potassium metasilicate, orthosilicate, or other potassium ratios instead of sodium silicates: W The alkaline potassium silicates can be produced in concentrates up to 4.5 pounds per gallon. This allows the producer to combine the caustic potash and potassium silicate before shipping so that the product is ready to use a t the plant without mixing and/or dilution. Sodium silicate concentrations, on the other hand, are limited to about 1.25 pounds per gallon. W Potassium orthosilicates solidify below -20°F, making them suitable for use in any climate. W Potassium silicates are superior alkaline builders because of their very high solubility. The trade-off comes in terms of cost. Potassium salts cost the same as or up to 1.7 times more than their sodium counterparts, and up to 1.1 to 1.5 times

+

+

Table 7-16: Liquid potassium silicate formulas k ( m o of KzO: SiOi)

1 (Potassium metasilicate) 2 (Potassium orthosilicate) 3 (31)

Caustic potash Potassium silicate (gallons') (gallons')

Formula KQsSi02 2K20.Si02 3KD&i02

9.2 14.1 16.2

72.7 8.0 5.8

'figures are gallons of caustic potash and potassium silicate needed to produce 100 pounds of alkali in 100 gallons of stock solution.

(depending on Na,O to SiO, ratio) a s much of the potassium silicate is required to obtain the same alkalinity. The chemicals used for producing liquid potassium silicates are: Liquid caustic potash Denslty, Ib./gal. Percent I40 Percent SiO, Soiidiflcation temperature

Liquid potassium silicate ( 1 3 . 2 9 )

12.09

37.8 0.0 -20°F

Potassium silicates are produced a t a concentration of one pound per gallon of solution by combining these chemicals in the proportions given in Table 7-16. As previously stated, potassium silicates can be produced in highly concentrated solutions. For example, 14.1 gallons of caustic potash and 8.0 gallons of potassium silicate will mix together without dilution. This solution contains 100 pounds of K,SiO, (potassium orthosilicate) or 100/22.1, which equals 4.5 pounds per gallon. Solutions of the same strength and concentration but a t significantly lower cost can be produced by substituting sodium silicate (1:3.22)for potassium silicate (l:3.29) in equal volumes. The chemical species produced by this substitution is about 85 percent potassium orthosilicate and 15percent sodium orthosilicate. Except for slight crystallization a t extremely low temperatures, little efficiency is lost with this substitution. Choosing an alkali The selection of silicated alkali depends on the type of soil being removed. A t first thought, it would seem that all silicated alkalies (orthosilicates, metasilicates) should produce the same results a s long a s the proper alkalinity is achieved in the break and subsequent baths. However, silicated alkalies may not all perform alike. For some time, operators have selected orthosilicate for linen supply operations and metasilicate for industrial laundering. The contention is that the oily soils present in linen supply items are primarily derived from animal fat, which needs the strong saponification action of the sodium oxide portion of the alkali to be removed.

To remove mineral oil-based soils found in industrial uniforms, shop towels, and similar classifications, the emulsifying action of metasilicate works b e s t In addition, shop towels laundered with metasilicate show greater absorbency than those laundered with orthosilicate when both alkalies are added to a n equal titration level.

DYEING TEXTILES IN THE PIANT Using stain-treatment formulas on heavily stained textiles shortens their life. An alternative is to redye heavily soiled items to a darker shade. Some plants also dye new textiles to customize certain services such a s continuous towels, mops, shop towels, and other specialty items. The dyeing process can be carried out in the plant or by a dye specialist. Direct dyeing Many operators direct dye wiping cloths a s part of the regular formula. Also, plants offering colored table linens can use a touch-up procedure to prevent a rainbow-of-hues effect caused by a mixing of new and used inventories. Wiping cloths may be purchased either a s greige (unbleached) goods or white fabrics. Many operators initially offer white wiping cloths and then dye them when they become too stained to serve. Direct cotton dyes are sufficiently washfast for wiping cloths and can be applied to fabrics being washed during the rinse bath or the break, or applied a s a separate procedure. The dye generally comes in pouches, each containing sufficient dye for the contents of the washer. When the dye is added to the third hot rinse, the rinse is extended to five or more minutes, followed by the usual split and cold rinses. However, this process is time-consuming, adds measurably to formula expense, and the dye doesn't penetrate the fabric well. Adding the dye packet a t the break improves the process; it has a long time to exhaust before the bath is drained. The dyestuff works independently of the detergent to accomplish its task. The most effective method of'direct dyeing in the washer relies on additional time and steps to achieve a washfast color. This is the procedure: load the textiles and draw a high level of hot water; add the dye and increasethe water temperature to 200°F by direct admission of steam; agitate the load for 15 minutes to thoroughly distribute the dye; add rock or tablesalt, usually 10 to 20 pounds per 100 pounds of textiles (the salt lowers the solubility of the dye in water and forces it into the fibers); and B rinse the textiles four to six times. Vat dyeing

Textiles used in food service or wearing apparel must be vat dyed in order to resist fading during heavy-soil washing and/or bleaching. Vat dyeing also can be done in a regular laundry washer. Here's a n example based on a 42- by 84-inch open-pocket machine loaded with no more than 200 pounds of merchandise: draw eight inches of hot water into the empty machine a t a temperature of 170" to 190°F, adding about six ounces of nonionic synthetic detergent and a

weighed amount of anthraquinone (vat) dye; Irun the washer for about a minute, add 10 pounds of caustic soda, and allow

several minutes of mixing; Iadd the load of merchandise to be dyed; Irun the load for at least five minutes, then add sodium hydrosulfite, 2.5

pounds a t a time, up to 12.5 pounds; Irun the machine an additional 30 minutes and add one quart of 1.0 percent

chlorine bleach; Irun the machine an additional 10 minutes; Igive the contents of the washer three high-level rinses, all hot, followed by a

regular light-soil washing formula. Although this procedure has been used for many years, it's complicated and time-consuming, and it involves chemicals not commonly used in the professional laundry, notably sodium hydrosulfite. An easier alternativeis to use premixed vat dye kits from chemical and textile distributors. Dye specialists Some companies specialize in vat dyeing textiles, saving operators from the tedious procedure of dyeing textiles in the washer. These dye specialists color merchandise to the desired shade and convert stained goods to useful life.

SAFE HANDLING OF WASHROOM CHEMICALS

N

ormal operating procedures in a laundry create several safety issues for the employees. The very nature of the work being performed i n a laundry environment exposes employees to slippery floors, moving equipment parts, hot water, high-temperature metal surfaces, live steam, hazardous chemicals, microorganisms, soils, and extremes in both air temperature and humidity. Employers can control the risk to employees by providing appropriate safety equipment, training, and first-aid information and materials. This chapter deals primarily with hazards from chemicals used in the washroom and is not intended to be all-encompassing. Employers must continually review current publications to obtain the most up-to-date legal requirements.

CHEMICAL HANDLING Chemicals used in the washroom can be classified into the following broad categories: Ialkalies and alkaline builders, Isurfactants and detergents, Isours and acids, Ibleaches (oxidizing type), Isolvents, and Ispecialty chemicals. The potential for danger when using the above compounds depends a great deal on their strength. Most of the chemicals are hazardous in their concentrated forms. Although makeup solutions and stock solutions are less hazardous than the concentrated form, they must be handled properly. All employees and supervisors who handle any washroom chemical must read the product label and the Material Safety Data Sheet (MSDS) supplied by the manufacturer. In addition, everyone handling these chemicals must have access to and use all appropriate protective devices such a s protective clothing, breathing devices, gloves, goggles, ventilation systems, eye-wash stations, and safetv showers. Each employer is responsible for providing proper facilities and training in required procedures and use of safety devices. Management is responsible for

Figure 8-1: NFPA hazardous material code with numerical scale

ensuring that employees follow established procedures.

CHEMICAL STORAGE Many of the classes of compounds available in the washroom are capable of reacting with each other and must be stored separately. In general, alkaline materials must be stored separately from acid materials such a s sour, and chlorine bleaches must be stored separately from acids. The same precautions apply to transporting washroom chemicals - do not move incompatible items together on the same pallet.

HEALTH HAZARD 4 Deadly

4 Below 73°F

3 Extreme danger

2 Hazardous (Boiling pt. atfabove 1 0 0 ~ ~ andfor atfabove 73'F-not

hazardous

0 Normal material

HAZARD COMMUNICATION STANDARD OSHA's Hazard Communication Standard, sometimes referred to as the Right-to-Know Law, establishes uniform requirements to make sure that the hazards of all chemicals produced in, imported into, or used in U.S. workplaces are evaluated, and that this information is transmitted to the people who use the chemicals. Among the rights the law grants to employees is theright to certain kinds of information about specific health and safety aspects of chemicals the employee handles or is exposed to in the workplace. All employers using hazardous chemicals must develop and implement a written hazard communication program that includes labels on containers, MSDSs, and training to give this information to their employees. The training can be in written or oral form but should be generally nontechnical and easily understood by employees.

Container labels A chemical container label provides the following information: Ihazard rating, Ihazardous ingredients, precautions of use, and Ifirst-aid instructions. In addition, the container label may contain information about a chemical's flammability, health, and reactivity rating as defined by the National Fire Protection Association (NFPA). The NFPA codes are an approved method of rating the hazard level of chemicals. They provide an easy way to identify the hazardous properties of the chemical under normal and emergency situations. NFPA uses a four-color, diamond-shaped symbol. Each color has a special hazard meaning: red a t the top (fire),yellow (reactivity), white (specific hazard), and blue (health). The level of the hazard, indicated by a number from zero to four, or specific hazard identification abbreviations are printed in the color box referring to the type of hazard. (See Figure 8-1.) The numerical values mean: 4-Severe hazard I3-Serious hazard I2-Moderate hazard I1-Slight hazard I0-Minimal hazard The following explanation of the numerical values is taken from "Recom-

X

Yellow

4 May detonate

SPECIFIC

3 Shock and heat

HAz4RD

Oxidizer Acid .ACID Alkali o v Use NO WATER w Rodiwctive

&R"

/ /

\/ f 1

f'

V

may detonate

2 Wolent

chemical change 1 Unstable if heated 0 Stable

I i

1 f

mended System for the Identification of the Fire Hazards of Materials," (NFPA No. 704M). IFlammability 4 Very flammable gases, very volatile flammable liquids, and materials that in the form of dusts or mists readily form explosive mixtures when dispersed in air. Shut off flow of gas or liquid and keep cooling water streams on exposed tanks or containers. Use water spray carefully in the vicinity of dusts so as not to create dust clouds. 3 Liquids which can be ignited under almost all normal temperature conditions. Water may be ineffective on these liquids because of their low flash points. Solids which form coarse dusts, solids in shredded or fibrous form that create flash fires, solids that burn rapidly, usually because they contain their own oxygen, and any material that ignites spontaneously a t normal temperatures in air. 2 Liquids which must be moderately heated before ignition will occur, and solids that readily give off flammable vapors. Water spray may be used to extinguish the fire because the material can be cooled to below its flash point. 1 Materials that must be preheated before ignition can occur. Water may cause frothing of liquids with this flammability rating number

if it gets below the surface of the liquid and turns to steam. However, water spray gently applied to the surface will cause a frothing which will extinguish the fire. 0 Materials that will not burn.

W Health 4 A few whiffs of the gas or vapor could cause death; or the gas vapor or liquid could be fatal on penetrating the fire fighters' normal full protective clothing, which is designed for resistance to heat. For most chemicals having a Health 4 rating, the normal full-protective clothing available to the average fire department will not provide adequate protection against skin contact with these materials. Only special protective clothing designed to protect against the specific hazard should be worn. 3 Materials extremely hazardous to health, but areas may be entered with extreme care. Full-protective clothing, including self-contained breathing apparatus, rubber gloves, boots a n d bands around legs, arms, and waist should be provided. No skin surface should be exposed. 2 Materials hazardous to health, but areas may be entered freely with self-contained breathing apparatus. 1 Materials only slightly hazardous to health. I t may be desirable to wear self-contained breathing apparatus. 0 Materials which on exposure under fire conditions would offer no health hazard beyond that of ordinary combustible material.

W Reactivity 4 Materials which in themselves are readily capable of detonation or of explosive decomposition or explosive reaction a t normal temperatures and pressures. Includes materials which are sensitive to mechanical or localized thermal shock. If a chemical with this hazard rating is in a n advanced or massive fire, the area should be evacuated. 3 Materials which in themselves are capable of detonation or of explosive decomposition or of explosive reaction but which require a strong initiating source or which must be heated under confinement before initiation. Includes materials which are sensitive to thermal or mechanical shock a t elevated temperatures and pressures or which react explosively with water without requiring heat or confinement. Fire fighting should be done from a n explosion-resistant location. 2 Materials which in themselves are normally unstable and readily undergo violent chemical change but do not detonate. Includes materials which can undergo chemical change with rapid release of energy a t normal temperatures and pressures or which can undergo violent chemical change a t elevated temperatures and pressures. Also includes those materials which may react violently with water or which may form potentially explosive mixtures with water. I n advanced or massive fires, fire fighting should be done from a protected location.

1 Materials which in themselves are normally stable but which may become unstable a t elevated temperatures and pressures or which may react with water with some release of energy but not violently. Caution must be used in approaching the fire and applying water. 0 Materials which are normally stable even under fire exposure conditions and which are not reactive with water. Normal fire fighting procedures may be used. Material Safety Data Sheets (MSDSs)

Under the provisions of OSHA's Hazard Communication Standard, employees have the right to examine any Material Safety Data Sheet (MSDS) upon written request. Employers must maintain MSDSs for all hazardous chemicals in use in the workplace and must make them available for employee review. In addition, MSDSs must be readily available to emergency personnel in the event of fire or other emergency. The MSDS contains more detailed information than the product label and should always be consulted during a n emergency. A typical MSDS is divided into sections of required information. The information may appear in a different order, but it will always be labeled for easy identification. The sections are: W P r o d u c t identification. Gives both the name and chemical family of the product. H a z a r d o u s components. Identifies the components of the product considered to be hazardous by EPA or OSHA standards. This information is based on the hazardous nature of the component in its pure and concentrated state, and includes exposure limits for the concentrated material. In general, exposure to a formulation of the material represents a lesser hazard than what's indicated by the MSDS because the material is diluted with water and/or other chemicals. W P h y s i c a l d a t a . Lists the chemical and physical properties of the substance. W F i r e a n d e x p l o s i o n d a t a . Contains essential information in the event of a fire or other emergency, including proper fire fighting techniques in the presence of the material. R e a c t i v i t y d a t a . Describes hazardous conditions to avoid and hazardous products that can form if the material chemically decomposes. H e a l t h h a z a r d d a t a . Describes chronic or acute effects of exposure and provides first-aid information. Anyone handling the product must thoroughly understand emergency and first-aid procedures and must make certain t h a t the required items for first-aid treatment are readily available. For washroom chemicals, the normal first-aid procedure is to thoroughly flush the affected body area with water, either in a safety shower or eye wash station. W P r e c a u t i o n s f o r s a f e h a n d l i n g a n d use. Describes precautions for handling a spill or disposing of the product and precautions to be taken in general handling and storage. W C o n t r o l m e a s u r e s . Describes protective devices for safe handling of the product.

The best source of information on handling washroom chemicals is the

MSDS for the product in question. Employee fraining

Every employer is responsible for providing a safe working environment and training all employees required to work with or be exposed to any hazardous or toxic substance. The training includes proper safety procedures and hazard information on the substance. This chapter only highlights the major provisions on laws relating to safe handling of chemicals. Operators must consult the most recent edition of national, state, and local regulations to ensure compliance.

PROBLEM SOLVING AND TROUBLESHOOTING

D

iagnosing problems in the washroom involves analyzing both t h e mechanical and chemical processes necessary to producegood quality. This chapter presents information and procedures for troubleshooting mechanical and chemical problems a s well a s tests operators can perform in the plant to maintain consistent quality in day-to-day operations. While it concentrates on washroom chemistry, it nevertheless touches on many phases of operations. Machine maintenance is not covered in this chapter. However, properly maintained equipmentis a prerequisite for using the procedures described here. For example, leaking fill and/or dump valves can lead to wrong titration values i n the same manner a s improper chemical use can.

TROUBLESHOOTING TYPICAL OPERATING PROBLEMS Plant and production managers are constantly faced with quality problems. Here are some typical problems and possible causes. P o o r s o i l removal: - Suds bath was too low. - Suds time was too short. - Washing temperature was too low. - Not enough detergent was added. - Washer was overloaded. - Water levels were too high/low. - Water was too hard. - Soil loads were mixed. - Wrong formula was used.

Poor color (redeposition): - Water was too hard. - Washers were overloaded. - Not enough detergent was used. - Detergent ingredients were poorly balanced. - Formula didn't call for enough rinses. - Rinse times were too short.

P o o r color (not redeposition): - Dye transfer occurred. - Bleach was used incorrectly. - Washing temperature was too high. - Alkalinity was too high. - Textiles lacked colorfastness. W P o o r color, w h i t e s ( o t h e r t h a n redeposition):

- A yellow or brown color indicates: iron poor rinsing undersouring unneutralized bleach - Yellowing indicates chlorine-retentive resins. - Pink indicates an iron/bleach/brightener complex. - Green indicates: W metallic salts W dye bleeding - A dull appearance indicates: W not enough bleach W weak bleach W short bleaching time W not enough flushes W not enough rinses W short rinses W poor soil removal W P o o r s t a i n removal: - Temperatures weren't controlled in preliminary flushing. - Not enough bleach was added. - Bleach stock solution was too weak. - Bleach pH was incorrect. - Washing temperature was too low for the detergent. - Water level in bleach bath was too high. - Washer was overloaded. - Bleach bath contained too much soil. - Bleach time was too short. - Improper bleach for stain type was used. - Alkalinity was too low. - Not enough soap/detergent was used. - Sudsing time was insufficient. - Sudsing temperature was too low. - Merchandise was abused in customer locations. W W W W

W H i g h tensile s t r e n g t h loss:

- Bleach wasn't diluted to one percent. -

Too much bleach was used. Bleach pH was too low. Bleach temperature was higher than 155OF Steam had escaped into the bleach bath.

- Mechanical action was excessive because of: underloading too lengthy formulas too much time between filling and draining low water levels - Highly alkaline builders were used excessively in the presence of steam and high water temperatures on fabrics containing polyester. - Wrong souring agents were used. - Souring agents were used improperly (too much/too little). W W W W

W Linting/pilling:

- Mechanical action was excessive because of:

underloading too lengthy formulas too much time between filling and draining water levels too low leaky washers (dump valves, shell, etc.) - Textile fibers are too short. - Textiles contain low-twist yarns. - Washers, conditioners, tumblers, or flatwork ironers have rough surfaces. - Too much bleach was used. - Textiles were exposed to excessive heat in tumblers. - The pH of bleach was too low. - Bleaching temperature was higher than 155°F. - Strong alkalies weren't rinsed out of polyester in fabrics before finishing. - Souring agents were improperly used. W W W W W

W O d o r i n textiles:

- Hard water reacted with soap.

- Poorly soured loads have fermented. - Too much sour was used. - Soil remains in the textiles. - Rinsing was incomplete. - Boiler treatment chemicals have contaminated the load.

- Resin-treated fabrics have retained soil and chemicals.

W F l a t w o r k r o l l i n g o n ironer:

- Rinsing was incomplete. - Too much sour was used. - Souring time was too short. - Sour was added improperly.

- Wrong type of sour Mias used. - The work was too damp. - Ironer chests were dirty.

- Chest was lubricated improperly. - Starch or other substance such as wax has accumulated on chests. - Rust is present on chest surfaces.

- Ironer chests have been assembled in the wrong machine sequence.

- Chests were cold because of: Iimproperly sized steam lines Itoo low steam pressure Iimproperly operating traps Iair-bound chests - Chests were warped. - Static electricity was present. - Goods were improperly feeding. - Fabrics lacked lubrication. - Apron covers, padding, ribbons, and guide strings were poorly maintained. IGarment wrinkling: - Washers were overloaded. - Cool down in rinsing was too rapid. - Time between washer reversals was too long. - Drain times were too long. - Cylinder rotation speed was too slow. - Intermediate extraction was used. - Extraction time was too long. - Extraction speed was too high. - Basketloads awaiting hanging were overloaded. - Delay before hanging was too long. - Steam has leaked.

CAUSES OF TEXTILE DAMAGE Textile damage is a source of concern to all laundry plant operators. Textile degradation is expected in normal use from physical abrasion and flexing during wear and laundering, chemicals used in laundering, and oxidizing agents in the environment. This relatively long-term deterioration is an anticipated part of the cost of operation. On the other hand, abnormal textile damage that becomes apparent after items have been laundered only a few times or suddenly and unexpectedly after many launderings signals problems in the plant or a t the customer's, or indicates a n inherent weakness in materials received from the mill due to imperfections in the manufacturing process. Chemical and physical laboratory tests often must be conducted by experienced analysts to determine the true extent and nature of the damage. Textile damage usually can be classified into a few major categories. The most common ones are described here. Chemical damage during use

Chemical damage occurs when the chemical makeup of fibers i s altered in a way that causes a decrease in tensile strength. Chemical damage results when textiles are exposed to: U acids, I alkalies, oxidizing agents, I certain atmospheric gases that have a degrading effect, I light and other types of radiation, and I high temperatures in drying or pressing.

-

Also, operators handling doctors' and nurses' uniforms, towels from medical or dental offices, and hospital linens have to contend with holes caused by: Imedicines; Initric acid; Isilver nitrate; Ialum; Iferric chloride; Idisinfectants and antiseptics such as hydrogen peroxide, hypochlorites, potassium permanganate, merthiolate, mercurochrome, carbolic acid, cresols, and iodine; and Iastringents such a s zinc sulfate, zinc chloride, and aluminum chloride. Much of the chemical damage from these corrosive substances occurs when the solutions dry on the textiles. During drying the solutions evaporate and become increasingly concentrated. If the chemicals remain on the textile for any length of time, they cause serious degradation, which in most cases does not become apparent until the textile has been laundered once or twice. This damage occurs after laundering because chemically treated cotton loses its wet strength more rapidly than its dry strength. Degraded cotton textiles often retain sufficient dry strength to remain intact during use, but fail, developing holes and tears, during laundering or while the textile is wet. Textile strength measurements on unused cotton indicate wet strength is 1.2 to 1.3 times dry strength. Chemically degraded cotton, on the other hand, has lower wet strength than dry strength; severely damaged textiles can have a wet strength less than half the dry strength. Numerous studies have been conducted on the effect of various chemical agents on the strength of cotton textiles. One study revealed strength loss ranging from 16.6 to 65 percent when certain common medicines were allowed to remain on cotton textiles for three weeks. Findings from this study appear in Table 9-1.

Table 9-1: Chemical damage to cotton caused by common medicines (3-week exposure) Staining substance

Percent loss in bursting strenglh

Tincture of ferric chloride .............................................. 65.0 Picric acid solution (2%) .............................................. 55.8 Tannic acid (5%) ..................................................... 30.1 Tincture of merthiolate ................................................ 21.7 Silver nitrate solution (12%). ........................................... 19.4 Iodine (7%) ointment ................................................. 19.4 lcyfhyol(10%) ointment.. ............................................. 18.6 Syrup of phosphate. .................................................. 17.1 Zinc chloride solution ................................................. 17.1 Mercurochrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16.6

Foodstuffs also cause appreciable damage to textiles. Frequently acidic substances in foods are responsible for much of this damage, although other substances also can degrade textiles. Table linens and napkins, a s well a s shirts and other wearing apparel, often develop holes because of the corrosive effect of foods. Even spinach, when spilled on cotton textiles and allowed to age for a s short a time a s two weeks, will cause sufficient deterioration to produce holes t h e first or second time the textile is laundered. Textile soiled with medicines or foods t h a t have been allowed to dry and age plainly show some damage when examined under a n ultraviolet lamp; this damage may not be visible to the unaided eye. Table 9-2 gives pH values for a number of common foodstuffs. All of these foods are strongly acidic. Chemical studies of the composition of fruits and vegetables show that oranges, grapefruit, a n d lemons are rich in citric acid. Grapes contain potassium hydrogen tartrate, a n acid salt. Cranberries, plums, and prunes contain benzoic acid. Oxalic acid is present in spinach, beet greens, and pineapple. The oxalic acid content of spinach varies from about 0.5 to 1.2 percent, depending on the variety of spinach. Table 9-2: pH value of foodstuffs Food

pH values

Apples. ............................................................. .2.9-3.3 Apricots ............................................................ .3.&4.0 Blackberries ......................................................... .3.2-3.6 Cherries ............................................................ .3.2-4.0 Cider ............................................................... .2.9-3.3 Gooseberries ........................................................ .2.8-3.0 Grapefruit .......................................................... .3.0-3.3 Jellies (fruit) ......................................................... .2.8-3.4 Lemons ............................................................. .2.2-2.4 Limes ............................................................... .I .8-2.0 Olives .............................................................. ,363.8 Oranges ............................................................ .3.0-4.0 Peaches ............................................................ .3.4-3.6 Pears ............................................................... .3.6-4.0 Pickles (dill) ......................................................... .3.2-3.6 Pickles (sour). ....................................................... .3.0-3.4 Plums. .............................................................. .2.8-3.0 Rhubarb.. .......................................................... .3.1-3.2 Sauerkraut .......................................................... .3.4-3.6 Soft drinks.. ......................................................... .2.0-4.0 Strawberries ......................................................... .3.0-3.5 Tomatoes ........................................................... .4.0-4.4 Vinegar. ............................................................ .2,4-3.4 Wines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.8-3.8

The acids found in fruits and vegetables, with the exception of oxalic acid, are weak acids t h a t ordinarily would not be considered corrosive materials. However, when foodstuffs containing these substances are spilled on textiles a n d permitted to remain and evaporate, a relatively concentrated amount of acid crystals results. With the aid of moisture from the air, the action of the acid eventually breaks down the cellulose. I

!

I

Damage tom fungi

Certain microorganisms, especially molds, cause significant textile damage. Molds or fungi are found practically everywhere, and the varieties that can damage textiles are numerous. The coating or discoloration on cotton, linen, or other materials that results from fungi growth is called mildew. Most fungi grow best in humid conditions a t temperatures ranging from 70° to 90°F. Many fungi can withstand freezing for months or years, but their growth is slowed a n d they eventually die when exposed to higher temperatures. Temperatures of 160°F or higher will kill fungi, usually in a few minutes. Fungi can use a large variety of materials a s food sources. They're able to do so by secreting a number of different digestive enzymes t h a t chemically change the materials into simple-soluble materials t h a t the organisms use for food. Practically all materials, with the exception of metals, are considered food sources by fungi. In addition to some types of textiles, leather, paper, paint and wood are subject to attack. Fungi have been known to corrode lenses of microscopes and other optical instruments under the proper growth conditions. Ordinarily, the cellulose fibers of cotton and linen have little or no nutritive value for higher organisms. Fungi, however, through the action of the specific enzymes they produce, are capable of decomposing cellulose for food. The extent of decomposition ranges from slight discolorations to extensive weakening of the fibers t h a t results in holes in the textiles. Molds also produce grey or grey-brown stains on fabrics. These stains may not appear until the affected textileis laundered and subjected to the heat of the tumbler or ironer. Table a n d kitchen linens are most often subject to mold damage. The damage occurs when the linens have been stored in dark, humid, warm places for a period of several days or longer before being picked up for laundering. Under these conditions, the almost universally present mold spores develop into mold plants, which grow prolifically. They attack the textiles and certain types of soils, specifically foodstuffs, in their quest for food. The longer the molds are left on the linen, the more damage they'll do. Methods for treating textiles to prevent mildew are presented in Chapter 5 . Mechanical damage

Mechanical damage to textiles is characterized by the abrading, cutting, or breaking of textile fibers and yarns. Mechanical damage results from: W normal wear; mechanical action during laundering; W cuts or snags made by sharp instruments; W abrasions;

cutting oftextiles by insects such a s moths or silverfish (Although they don't ordinarily attack cellulose, insects may use certain types of soil on textiles a s food. In consuming the food, they may cause damage to the fibers.); cuts from foodstuffs; and defective manufacturing procedures (These failures can be distinguised from mechanical damage of similar appearance only by careful examination.). Mechanical damage resulting from abrasion is common. For example, sheets and pillowcases may be dragged across hard, rough surfaces such a s bed frames and sometimes even concrete floors and truck beds. Snags and cuts from sharp instruments also arecommon. For example, hand towels can be damaged by razor cuts; the results may not appear until after laundering when the weakened fibers give way under the stresses of the laundering process. Tablecloths frequently receive knife cuts. Yarn failures that occur a t a n angle to the warp and filling yarns are almost certainly from knife cuts because tears in textiles always occur parallel to the warp or filling yarns. Mechanical damage also can be caused from materials imbedded in or overlaid on the textile. For example, when foods containing dissolved acids, salts, or even sugar evaporate on cloth, they form crystals or hard deposits of a noncrystalline nature in the spaces between the fibers. Crystals are well-defined structures with angular, often sharp edges that can abrade or actually cut textile fibers. Some foodstuffs such a s maple sugar or egg white beaten with sugar are relatively harmless to textiles from the chemical standpoint, but do form crystalline coatings that can cause mechanical damage. Damage to table linens, bedspreads, and the poorer grades of sheeting frequently can be traced to manufacturing imperfections or to impractical design. For example, some table linens and bedspreads, particularly items with special designs, are constructed to have many floats (yarns running over the top of the woven yarns without interlacing). Yarns that arenot interwoven usually have a very low twist and aren't very durable. The filaments are very easily broken by slight abrasion and by stresses encountered during wear or in the washer. Poorly constructed table linens and bedspreads often sustain physical damage during laundering. For example, some tablecloths made of cotton and rayon with jacquard designs contain many floated yarns of loosely twisted rayon filaments. This particular type of construction sacrifices durability for a n attractive appearance. Consequently, during laundering and even general use the loose floating yarns have a great susceptibility to wear a n d a tendency to snag, leading to increased possibilities of damage. Chemical damage during manufacture

During manufacture, textile damage can also occur in the finishing process. Chemical agents, particularly bleach, are usually responsible. As in laundering, bleach used in high concentrations or a t excessively high temperatures during manufacture causes marked degradation of fibers. Tests of many samples of cotton tablecloths t h a t have developed holes or even fallen apart during laundering have proven t h a t the damage was caused by overbleaching during manufacture. To check results, unlaundered items

from the same lots were also tested and showed evidence of chemical breakdown. Items that have been chemically damaged during manufacturing often show satisfactory strength before laundering; but during laundering the damaged yarns and fibers pull apart, leaving holes and tears. Damage in the laundry

Apart from the mechanical damage due to careless handling and to defective equipment, the main source of damageto textiles in the laundry is improper use of chemical agents, especially bleaches. The conditions necessary for proper bleach usage have been discussed in detail i n Chapter 4. But to reiterate, damage from bleach is most often caused by: using excessive amounts; failure to maintain the proper conditions of time, temperature, and pH; and leaving residual bleach in the textiles because of inadequate rinsing. Another source of chemical damage in the laundry is caused by leaving merchandise for extended periods in laundry baskets t h a t are made from two or more dissimilar metals or alloys, such a s brass and stainless steel. These metals provide the necessary conditions for electrolytic action when they come in contact with textiles containing moisture and salts from laundering. Electrolytic action produces corrosive chemicals in sufficient concentration to cause discoloration and permanent damage to the textiles. The damage isn't noticeable until the affected textiles are exposed to the heat of tumbling or ironing. Then the damaged areas appear a s brown spots, which often disintegrate and leave pinholes during use. A common mechanical problem t h a t causes damage to textiles in the laundry is overheated tumblers. Excessively high temperatures cause scorching. In addition, laundries that use perchloroethylene may encounter acid damage to textiles from overheated tumblers. When exposed to flames or redhot metal higher than 900°F, perchloroethylene can decompose to produce strong corrosive acids that can damage cotton textiles. This problem may be corrected by proper maintenance and operation of tumblers. Damage to polyester/cotton blends

While the cotton portion of a blended textile is subject to the same types of damage a s items of 100 percent cotton, the polyester portion has a higher resistance to chemical (other than alkali) and mechanical damage than does the cotton portion. A common occurrence in blended textiles is the almost complete removal of the cotton portion due to either chemical damage, a s described earlier, or mechanical damage. This mechanical damage is caused by a n abrasive action of the polyester on the cotton during use and laundering. The flexing of the blended fabric causes the polyester fibers to cut or abrade the cotton fibers into short lengths. These short cotton fibers are removed in laundering, usually appearing a s lint. Many laundries observe more lint from blends than from allcotton items due to this action. The polyester portion of blended fabrics most often is damaged by strong alkaline solutions. This damage, called alkaline hydrolysis, is greatest a t high

temperatures or in the presence of quaternary ammonium compounds (some softeners and some bacteriostats). Polyester fabrics are thermoplastic and become "relaxed" a t high temperatures. This relaxed state allows the fiber to free itself of wrinkles and return to the desired shape. However, wrinkles are believed to be set into polyester by too-rapid cooling from a relaxed state. This problem usually occurs during rinsing as the water temperature is lowered and is often referred to a s thermal shock. Overloading increases the amount of wrinkling because of increased compression of the load and erratic cool down.

Turnbull's b l u e t e s t Chemicals: 1. Solution A - 10 grams of ferrous sulfate per liter of water. 2. Solution R - 10 grams of potassium ferricyanide per liter of water.

TESTS F O R DAMAGE A number of tests can be used to evaluate the nature a n d extent of damage to

Obseruation: A deep blue color shows the presence of carboxyl groups, indicating cellulose damage.

fibers a n d textiles. The procedures listed here are for analyzing some of the types of damage typically found in a professional laundry. For a comprehensive listing of test methods, refer to more specialized sources such a s Analytical Methods for a Textile Laboratory, Third Edition, American Association of Textile Chemists and Colorists, 1984. Chemicals referred to in the following tests may be purchased from local chemical supply companies. Teds for chemical damage to cellulosic fibers (coffon, linen)

Fehling's solution chemicals: 1. Solution A - 60 grams of copper sulfate per liter of water. 2. Solution B - 346 grams of potassium sodium tartrate and 100 grams of sodium hydroxide per liter of water. Procedure: 1. Mix equal parts of solutions A and B. 2. Immerse the sample i n the mixture and boil for 10 minutes. 3. Rinse in hot water (70°C, 158°F). Observation: Pink or red deposits (cuprous oxide) indicate the presence of reducing groups, which damage cellulose.

Harrison's test Chemicals: 1. Solution A - 80 grams of silver nitrate per liter of water. 2. Solution B - 200 grams of sodium thiosulfate and 200 grams of sodium hydroxide per liter of water. Procedure: 1. Dilute Solution A 1:20 with water and diluteSolution B 1:10 with water. 2. Mix equal volumes of the diluted solutions. 3. Immerse sample and boil for five minutes. 4. Rinse in Solution B dilution (1:lO). 5. Rinse i n hot water (70°C, 158°F). Observation: A gray or black deposit of silver indicates the presence of reducing (aldehyde) groups, which damage cellulose.

Procedure: 1. Immerse the sample in Solution A. 2. Rinse in warm water (55"C, 131°F). 3. Immerse in Solution B for five minutes. 4. Rinse in hot water (70°C, 158°F).

R e s i s t d y e i n g test Chemicals: A solution of 5 grams of Chlorazol Sky Blue F F (C.I. Direct Blue 1) per liter of water. Procedure: 1. Immerse the sample in the dye solution a n d boil for five minutes. 2. Rinse in hot water (70°C, 158°F). Observation: Light spots show the presence of carboxyl groups, indicating cellulose damage. Muller's t e s t Chemicals: 1. Solution A - 10 grams of phenylhydrazine-p-sulfonic acid per liter of water. 2. Solution B - 2 grams of Fast Blue Salt (C.I. Azoic Diazo Component 48) and 1 gram of sodium bicarbonate per liter of water. Procedure: 1. Immerse two samples in Solution A (boiling). 2. Remove one sample after 30 seconds, the other after one hour. 3. Rinse both samples thoroughly in warm water (55OC, 131°F). 4. Immerse both samples in Solution B (room temperature) for 20 minutes. 5. Rinse in hot water (70°C, 158°F). Obseruations: 1. Sample 1(30 seconds in Solution A, 20 minutes in Solution B) - a brownred stain indicates oxycellulose (bleach/alkali damage). 2. Sample 2 (one hour in Solution A, 20 minutes in Solution B)-a red-violet stain indicates hydrocellulose (mineral acid damage). Tests for chemical damage to nylon (and other polyamide) fibers

Ninhydrin test Chemicals: 5 grams of ninhydrin per liter of water. Procedure: 1. Place a sample of damaged fabric and a sample of undamaged fabric in

the test solution and bofi for five minutes.

2. Rinse and allow to dry. Observation: If the damaged sample absorbs less dye and is a different shade than the undamaged sample, damage from light is indicated. Samples damaged by acid or alkali absorb more dye than the undamaged sample. Test for damage to polyester W N,N-dimethylparaphenylenediaminehydrochloride test

Chemicals: A solution of 0.2 grams of N,N-dimethylparaphenylenediamine hydrochloride, 5 milliliters of 0.4 N potassium hydroxide, 95 milliliters of methyl alcohol, and 100milliliters of benzene. (Dissolvethe 0.2 grams in the potassium hydroxide, then add the methyl alcohol, followed by the benzene.) Procedure: Immerse the sample in the test solution and shake it for two hours. Observation: A yellow-brown stain indicates damage from weathering.

TESTS K)R BACTERIOLOGICALGROWTH A number of bacteriological tests designed to monitor the presence and/or type of bacteriological species on equipment and/or fabric are available to the laundry operator. Specialized training and equipment are needed to perform culture-type evaluations. Hard surfaces such as laundry carts, washing machines, and trucks are normally evaluated. A trained technologist collects samples fromvarious locations. The samples are cultured to encourage bacterial growth, and the colonies of bacteria are identified and counted to determine the type and level of contamination. Culture testing i s especially appropriate in healthcare applications. Textile surfaces such a s ironer covers and press covers are not normally evaluated using the above procedure. The porous and rough texture of these surfaces makes obtaining accurate samples for evaluation difficult. Researchers have had success using impression plates, a method in which fabric surfaces are pressedinto a growth medium and later cultured, identified, and counted. However, research indicates that the transfer to impression plate i s not always complete, leaving some organisms undetected because they didn't transfer to the medium. A more accurate procedure for evaluating bacteriological species on fabric is to cut a specimen of the fabric, pulverize the specimen in a blender, and sample the resulting solution. Some tests are designed to monitor the performance of bacteriostatic or bactericidal finishes, either permanent or laundry applied. The standard test used to evaluate the effectiveness of a finish is the zones of inhibition test. The technologist takes samples of the fabric, places them in a bacteriological media, adds bacteria species to the media, and allows them to grow. After a specified period of time, the technologist evaluates the samples in terms of zones of inhibition, which measure how close to the fabric sample the

bacteria are able to grow. Effective bacteriostatic and bactericidal agents prevent growth of the bacteria species toward the fabric. The greater the distance between the bacteria growth and the fabric, the more effective the finishing treatment.

STAIN REMOVAL METHODS Most of the stains encountered in the professional laundry are removed in the regular washing process. The stains remaining after washing are generally of unknown origin, although long experience usually allows operators to judge the basic character of the stain - grease- or oil-based, rust, and so forth. Many methods have been developed to deal with the large number and variety of stains encountered on textiles. In professional drycleaning, stains are dealt with on an individual basis, and highly skilled spotters employ specific stain-removal procedures for known and unknown stains. However, the professional launderer, working with largevolumes of textiles, simply cannot treat stains on a n individual basis. Stains must be treated in bulk. This approach is presented in this section on stain removal. The stain removal procedures discussed here have been reduced to a few basic treatments, each of which can be applied to large volumes of stained fabrics in the washer. (Detailed formulas a m e a r in Tables 9-3 and 9-4.) Stains are grouped broadly into four basic categories: 1. grease- and oil-based (animal or vegetable derived), 2. oxidizable (many foods and medicines), 3. reducible (dye), and 4. metallic (aluminum and rust). The proper approach to dealing with these stains is to remove each of them sequentially in the washer by the shortest, simplest, and least costly procedure that preserves the color and strength of the fabrics being treated. A

A

Grease and oil-based stalns Grease- and oil-based stains come from a number of sources. Body oils and greases, either exuded or applied, stain wearing apparel. The numerous fatty substances contained and used in food are found on restaurant linen and garments. On cotton, these stains usually yield to high temperature and high alkalinity for extended periods of time. One treatment is a n alkaline boil (boil out): Draw a low water level. W Add about three pounds of anhydrous sodium orthosilicate per 100 pounds of textiles and sufficient soap or synthetic detergent to produce a heavy suds a t temperatures ranging from 195O to 205OF. Agitate for 30 minutes to three hours. Rinse. This treatment does have drawbacks. It consumes large amounts of time, supplies, and energy. It also affects tensile strength because the textiles are processed a t high temperatures in oxygenated water of very high alkalinity. An alternative treatment is to use a surfactant-based formula with less alkalinity and lower temperature. Surfactant-based products are also more effec-

tive than alkaline products on mineral-oil stains. The recommended formula is: H Draw a low water level a t 180°F. H Add about four pounds of product per 100 pounds of textiles. H Agitate for 20 minutes. H Rinse. Oxidizable stains

These stains are from the color-based materials found in foods, medicines, and cosmetic preparations. They yield to the action of an oxidizing bleach, such a s chlorine, hydrogen peroxide, or even sodium perborate. These stains require strong bleaching action, much more intense t h a n the bleaching action encountered in the regular washing process t h a t they may have already undergone. However, a n intensified bleaching process leads to a decrease in tensile strength. To minimize this problem, the formula calls for a low temperature. By reducing the bleaching temperature from 160' to 88OF, bleach activity is reduced sixteen fold (six percent of the activity a t 160°F),allowing for corresponding increases in bleach-bath strength. An overnight soak is the most effective way to bleach out oxidizable stains: H Draw a high level of water a t a temperature not exceeding 80°F. H Add 5 to 15 quarts of one percent bleach per 100 pounds of fabric. I Soak the textiles for four hours to overnight. I Add antichlor to the rinse water to deactivate the heavy concentration of bleach. Reducible stains

Reducible stains generally are dyes, most commonly hair preparations, but also other fugitive dyes encountered in the professional laundry. They require the action of reducing bleaches; the most common one used is sodium hydrosulfite with an alkali such a s soda ash. The process is: H Draw a low water level a t 160°F. H Add sodium hydrosulfite a t the rate of 2 pounds per 100 pounds of fabric. I Agitate for about 20 minutes. H Rinse.

oxalic acid treatment generally is the first used in any sequential stain removal procedure; it can be removed or neutralized by subsequent treatments in the cvcle. The process is: H Draw a low water level a t 150' to 160°F. I Add oxalic acid a t the rate of 8 to 16 ounces per 100 pounds of textiles being processed. I Agitate for about 20 minutes. I Rinse three or four times. The stain-removalsequence in the washer

The common stain-removal procedure in the washer combines the boil out, bleach treatment, and oxalic treatment into a single formula. The reducing bleach treatment is used only in special instances. Table 9-3: Stain-removal procedure for unknown stains Water level

Temperature

Operation

("F)

Time (min.)

Supply type

Bleach soak

High

80

Overnight

Bleach

Rinse

High

110

3

Rinse

High

110

1

Rinse

High

110

1

5 to 15 quarts of 1%bleach

M u m b~suif~te 2 ounces

Fabrics still stained should be set aside and treated as follows: Reducing sour

Low

150

15-20

Rinse

High

150-160

1

Rinse

High

150-160

1

Boil out

Low

195-205

60-180

Metallic stains

Iron rust i s the most common stain in this group. Rust stains are removed by a reducing agent such a s oxalic acid, sodium or ammonium bifluoride, sodium trisulfate, or hydrofluoric acid. The bifluorides and hydrofluoric acid are relatively safe for fabrics because they can be left in textiles in lower concentrations without danger of tendering or weakening the fabric. The fluoride compounds are hazardous and must be used carefully. Hydrofluoric acid, in particular, can be fatal to humans and must be used only with extreme caution. Oxalic acid is a reducing sour, and its reducing action also is effective against other reducible stains in the load. However, it's very damaging to cotton if allowed to remain in the textile following treatment. For this reason, the

Supply usage per I00 Ibs.

Rinse

High

150-170

1

Rinse

High

130-150

1

Rinse

High

100-120

1

Rinse

High

110

1

Rinse

High

110

1

Sour

Low

110

4

Oxal~cacid

8 to 16 ounces

Sodium orthosilicate

4 pounds

Soop or detergent

To suds

Sour

To des~redpH

Experience shows that the overnight bleach soak (top portion of Table 9-3) normally removes between 70 a n d 85 percent of all stains encountered in the professional laundry. This procedure does not take time out of the productive day and frequently is carried out a s a single step. The 15to 30 percent of stained textiles that don't respond to the treatment are set aside for oxalic treatment and boil out (bottom portion of Table 9-3), which must be done during production hours. A plant processing 100,000 pounds per week with three percent stain reject has a weekly stain load of 3,000 pounds. This represents four 800-pound overnight loads a week, but only one load needs to be treated with oxalic acid and boiled out. The reducing bleach treatment (Table 9-4) is used only in special instances in which stains are known to be reducible. These stain-removal procedures (Tables 9-3 and 9-4) are intended only a s guides to problems currently being experienced in the industry. Various segments of the textile rental industry encounter high or low stain percentages depending upon the soil classification and the severity of washing. Table 96: Stain-removal procedure for reducible stains Water level

Temperature

Operation Flush

High

Hot

2

Low

150

15-20

Rinse

High

150-160

1

Rinse

High

150-160

1

Boil out

Low

195-205

-

("F)

Time (min.)

Supply type

Supply usage per 400 Ibs.

-

Reducing sour

Oxalic acid 8 to 16 ounces

-

Rinse

High

170-180

Rinse

High

150-160

60-180

Sodium orthosilicate

4 pounds

Soap or detergent

To suds

1 1 -

Rinse

High

150-160

1

Bleach

Low

150-160

20-30

Bleach

6 to 8 quarts of 1%bleach

Rinse

High

120-130

3

Sodium bisulfite

2 ounces

Rinse

High

100-120

1

Rinse

High

100-120

1

Sour

Low

100-120

-

4

-

Sour

-

-

To desired pH

For example, most linen supply classifications average about three percent, but bib aprons are likely to average much higher in stain rejection. This reflects the severe use and abuse aprons receive. Similarly, diapers t h a t are exposed to food and medicines are very stain-prone. Stain reject averages should be used a s a guide to washing intensity. For example, a washing formula that holds stain reject percentages in diapers below five percent may be taking a n inordinate toll on textile strength. Test pieces can help determine if washing intensity is too great. Similarly, hospital linens showing 10 percent stain reject may need a more intensive washing formula (greater concentration of alkali, detergent, bleach, higher temperatures, and longer washing time) to reduce stain rejects. Removing silver nitrate stains

Silver nitrate stains pose special problems in hospital and medical work. The above formulas don't work on these stains, but the following will: To spot stains: Make a cold 1percent alcoholic solution of iodine crystals and apply to the stained area. After a few minutes, decolorize the iodine-moistened area with a 3 percent sodium thiosulfate solution. Follow with regular laundry processing. To soak linens in bulk, two solutions are needed: To immerse garments, prepare a solution containing 11 ounces per gallon each of citric acid and thiourea. To soak garments overnight, use this solution diluted 30:l. Launder fabrics lightly following immersion or soaking.

LAUNDRY AND THE ENVIRONMENT

T

he professional laundry plant uses water and energy to process linen supply and industrial textiles. In the process, it discharges chemicals and soils a s wastewater and stack emissions. This chapter identifies water and air pollution considerations and how launderers can conserve energy. For more complete information on wastewater processes, refer to publications by TRSA and other sources. The material presented in this chapter provides a n introduction and historical perspective only.

WATER POLLUTION In the years following World War 11, the sudden rise in industrial and home construction forced many municipalities to enlarge their sewage disposal facilities and build new treatment plants to handle the increasing amounts of waste. To get the funds to build new plants and expand existing facilities, local governments had to find new revenues. Many decided to impose surcharges for handling industrial sewage rather than add to the residential tax burden. However, even the enlarged publicly owned treatment works (POTWs) couldn't keep up with two problems caused in part by laundry products used by both consumers and professional launderers: nonbiodegradable detergents were producing large amounts of stable foam in lakes, rivers, and streams. phosphates were enriching the water, causing rapid plant growth that accelerated aging of slow-moving bodies of water. Nonbiodegradable detergents POTWs use both chemical and natural processes to remove pollutants from wastewater effluent. Bacterial action is a key factor in water purification. Bacteria and other microorganisms in water, with the assistance of sunlight and dissolved oxygen, decompose many natural and synthetic substances. This phenomenon is referred to a s biodegradation, and substances acted upon by bacteria are said to be biodegradable. Most soils and chemical washing agents are completely biodegradable.

However, synthetic detergents produced from petroleum sources prior to 1963 were not easily biodegraded, and their wide use in consumer laundry detergents in the 1950s and early 1960s led to severe problems of foaming in streams and waterways. Standing suds on streams and sewage treatment ponds were a common sight a t that time. On Mondays and Tuesdays, traditional consumer wash days, foam heights often reached six or seven feet. Manufacturers of laundry detergents reacted by reformulating consumer products to combat this problem. Beginning on July 1,1963,nonbiodegradable detergents were gradually replaced by products meeting rigid standards for biodegradation established cooperatively by the government and the Soap and Detergent Association. Phosphates in detergents In the late 1960s,consumer groups expressed much concern about the presence of algae and slime in lakes, ponds, and waterways. This growth of algae and slime is termed eutrophication - the process by which aquatic vegetation grows to such a n extent that it clogs lakes and waterways, making them unfit for industrial use, navigation, and recreation. Research indicated that phosphorus compounds were causing eutrophication because of their nutrient qualities for plant life. Whether phosphorus in detergents is a principal cause of eutrophication is debatable. Both human excrement from sewage disposal plants and fertilizer contained in runoff from farm lands constitute major sources of phosphorus pollution. Chemists have tested and evaluated many possible replacements for phosphates in detergents, including carbonates, zeolites, citrates, and complex organic sequestering agents. None of these has proven to be as effective in the detergency process a s phosphates. In fact, some of these phosphate replacements have created new environmental concerns because they can resuspend heavy metal contaminants. This issue is not yet completely resolved. Certain localities ban the use of phosphorus and its compounds in laundry detergents. However, many other areas allow the use of phosphates in commercial laundry detergents figuring that the detergency benefits outweigh the small contribution to overall phosphorus levels. Wastewater regulations The professional laundry can expect to see higher costs to purchase water, higher costs to discharge polluted water, and severe limitations on the discharge of toxic or hazardous substances into municipal sewer systems. With the emergence of environmental protection agencies at every level of government from local to federal, industrial establishments are coming under increasingly stringent regulations governing sewer discharges. As substantial users of water, professional laundries have come under close scrutiny. Many municipalities now assess fees for industrial discharge based on the volume and characteristics of the wastewater. Pollutants normally measured as characteristics of wastewater are materials that consume dissolved oxygen, biological oxygen demand (BOD),and chemical oxygen demand (COD);materials (mineral-basedoiland grease) soluble in Freon or hexane; and heavy met-

als such a s cadmium, lead, mercury, and zinc. Normally, BOD and SS (suspended solids) are considered compatible to a POTW. However. POTWs have been setting limitations on the acceptable concentration of these compatibles and assessing a user charge for excess amounts discharged. POTWs also have been setting maximum discharge lirnits for oils, greases, and heavy metals. Limits on heavy metal concentrations can be particularly troublesome for some professional laundries. The cost of discharging water into a POTW probably will continue to increase a s municipalities charge higher industrial recovery costs and user fees or ad valorem taxes. Municipal sewer districts assess industrial recovery costs against most industrial dischargers to repay money loaned to the POTW to expand and upgrade its facilities. User charges or ad valorem taxes a r e assessed against users of a municipal sewer system depending on the amount of contaminants they discharge into the system. But perhaps even more of a concern to professional launderers is the fact that their ability to discharge many substances into municipal sewer systems is likely to be severely limited, if not banned, as the list of potentially toxic a n d hazardous substances is expanded by the federal Environmental Protection Agency (EPA).

WATER AND ENERGY CONSERVATION The cost of water for laundry processing has risen sharply in the past decade. The cost increase is attributable to the increased cost of water itself, to t h e added charge for sewage disposal, and to special user charges for discharging certain pollutants in sewage. An even more compelling reason for conserving water than its cost alone i s the fact that 40 to 60 percent of all water usedin the professional laundry must be heated. Obviously, the less water used, theless energy is required forheating. The rapid risein energy costs has given added impetus to the search for ways to reduce water consumption. Water can be conserved in a t least two ways: 1. Rinse waters can be recycled with no treatment. 2. Water can be recycled through a water reclamation system. By using the formulas listed in Chapter 7, laundry operators can reduce water use about 20 to 50 percent below traditional formulas without using a water reclamation system. Washer/extractors eliminate one rinse cycle by adding an intermediate extraction step between rinses. Obviously, because less rinse water is used o n equipment with intermediate extraction, less water is saved by reuse. Continuous washing systems can reduce water consumption to as low as one gallon per pound of merchandise. By design, continuous washing systems reuse a substantial portion of water and energy, which in part accounts for their increasing popularity. The cost of gas or oil required to heat water, generate steam, and run conditioning and drying equipment adds up to about 50 percent of total nonlabor variable laundry processing costs. For this reason, many operators closely monitor and control steam and hot water consumption and the use of gas i n

conditioning and drying. However, a total energy and water conservation plan requires vigilance throughout the operation: Physical plant and maintenance

Energy conservation in the plant starts with insulating hot water and steam pipes and tanks, inspecting steam traps, repairing steam and condensate leaks, repairing water leaks, and using low-energy light bulbs in all light fixtures. Boiler operation and heat recovery

For maximum savings, boilers must be maintained a t peak operating efficiency. More importantly, an efficient wastewater heat reclaimer can reduce energy consumption by a s much a s 40 percent over a-system with no reclaimer. Processing

Processing procedures offer many opportunities to conserve energy. Reduce h o t w a t e r temperatures. Many plants maintain hot water temperatures of 180°F.While this temperature may be needed for breaks, suds, and carryovers, it's often higher than needed for rinsing and souring. An energy-saving procedure here is to lower water tank temperature to 160°F or less and use a thermal control that adds steam to the wheel to boost water temperature as high as needed for the break. While some may argue that using steam in the hot water heating tank is more efficient than in the washer, a lower hot water tank temperature probably results in lower overall energy use. One reason for this is that light- and medium-soil formulas perform satisfactorily at a top temperature of 130" to 145OF. L o w e r w a t e r levels. Reducing water levels reduces the liquid/fabric ratio in each bath, which in turn reduces the efficiency of the dilution process. Many operators have attempted to reduce energy consumption by lowering suds levels by one inch and rinse levels by two inches. However, to offset the reduced dilution effect, they've had to add processing steps. For example, in many cases, lowering the rinse levels by two inches requires an additional rinse. In this situation, total water consumption actually increases rather than decreases. Substitute a n i n t e r m e d i a t e e x t r a c t f o r a rinse. This is frequent practice with washer/extractors. In general, a one-minute intermediate extract eliminates one rinse. This practice also represents a n efficient means of managing washing temperatures by reducing the amount of water requiring temperature change. Intermediate extraction decreases the amount of moisture retained in the fabric by approximately one-half of what is retained after a simple drain step. For example, 100 percent cotton retains 0.3 gallons of water per pound following a drain operation and only 0.15 gallons per pound following an intermediate extraction. Although this lost water must be made up in the next cycle after the intermediate extraction, the subsequent fill uses less water than does an extra rinse step. The intermediate extraction also provides the benefit of chemical consistency of the rinsing bath. Recover d r y e r heat. For many years, operators paid no attention to the energy lost in dryer and conditioner exhaust. However, the waste can be sub-

stantial. Two methods of conserving dryer heat are: 1. using a heat pipe (or wheel) unit, which warms incoming air by running it through a finned bank of tubes set in the dryer exhaust, and 2. recirculating air from the dryer. The first method is commonly used in heavy industry and has been adapted to the professional laundry. For the second method, factors such a s lint filtering and the moisture level and re-entry point of recirculated air must be considered when selecting, sizing, and installing air recirculating units.

AIR POLLUTION Increasingly stringent local regulations in various parts of the country control atmospheric pollution. Two emission standards that come under the jurisdiction of the EPA and that are being regulated a t federal, state, and local levels are particularly important to linen supply and industrial rental plants: 1. discharges of pollutants from boiler stacks, primarily from coal-fired and high-sulfur, fuel-oil-fired boilers, and 2. perchloroethylene (perc) emissions from drycleaning operations. The Occupational Safety and Health Administration (OSHA) also is imposing strict standards on the use of perchloroethylene. Usually, local agencies have the authority to enforce regulations that are more strict than federal government regulations. Therefore, each operator must exercise close vigilance over actions being taken, or considered, by state and local regulatory bodies.

WASHING AND FINISHING EQUIPMENT

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any considerations must be taken into account when selecting equipment for a laundry, including: machine capacity, physical space, capital costs return on investment, projected maintenance costs, availability and cost of utilities, quality level, production capacity, and labor costs. One function of washing equipment and related material-handling devices i s to minimize the number of times an item is handled during processing. Of course, the main function of washing equipment is to provide mechanical action necessary to dilute, suspend, and remove soil. The main function of finishing equipment is to aid in presenting an attractive product to the customer. This chapter reviews the washing and finishing equipment available to meet these goals.

CONVENTIONAL WASHING AND FINISHING EQUIPMENT Washers

Conventional washing equipment is designed only to wash textiles. Extraction takes place in a separate piece of equipment. Washers are horizontal cylinders of either conventional design (dual cylinder, one rotating, one stationary) or shelless (single rotating cylinder) that are manufactured to be loaded either a t the end or on the side. Conventional washer operation can be manual, semiautomatic, or automatic. A semi-automatic machine automatically controls inlet and dump valves, regulates water levels, and controls the time of each bath. A fully automatic washer also has automatic supply injection and, with auxiliary equipment, can be mechanically loaded and unloaded. The three configurations of washing cylinders are: open-pocket (Figure 11-I), split-pocket or Pullman (Figure 11-2),and Y-pocket (Figure 11-3).

Figure 11-1:Open-pocket washwheel (cutaway e n d view)

Figure 44-2: Split-pocket (Pullman) washwheel (cutaway e n d view)

and design of ribs, and desired action. The rotational speed a t the cylinder determines the G force developed by Equation 11-1. Equation 4 4-4: G force = dR2/704I 4

Where: G force = force at the inner edge of the cylmder circumference d = inside diarneter of cylinder in inches R = rotation rpm of cylinder

Figure 11-3: Y-Pocket washwheel (cutaway e n d view)

Open-pocket machines are generally considered to provide the best mechanical action for cleaning. However, unless the machines are equipped with tilting, cylinder elevation, or other unloading aids, the labor costs for unloading may be higher than for the other two cylinder designs, depending on the size of the washer. Mechanical action for washing and rinsing occurs when thecylinder rotates. For large-piece processing, the direction of rotation may be reversed a t regular intervals to prevent tangling and to better distribute washing chemicals. For small-piece processing in which tangling isn't a problem, many operators prefer to use washers that have been manufactured, modified, or programmed to rotate continuously in one direction. This results in significant electrical savings and 15 percent more mechanical action. The rotational speed of washers is determined by cylinder diameter, height

Low G-force washers tend to rotate the load in the lower part of the washer. High G-force (almost 1 G) machines push the fabric against the washing cylinder. Most conventional washers have a G force of 0.6 to 0.7 G to allow for lift, fall, and rotation of the textiles. The proper rotation speed in a n open-pocket machine lifts the load to a point above the midpoint of the cylinder a n d then allows i t to fall into the cleaning solution. This lift and fall provides the necessary mechanical action for cleaning. If rotation speed i s too slow, there is no lifting action. If rotation is too fast, the load will not fall. Load size and water requirements are determined by the diameter and length of the cylinder a n d shell, and space between the inner cylinder and outer shell. At least two water levels are needed for proper laundering and rinsing action. Low levels provide the least dilution of chemicals and are used for break, suds, carry over, bleach, and sour baths. High water levels provide maximum dilution of soil and chemicals and are used for flushing and rinsing baths. The high and low water levels are determined by the ratio of water to fabric. Suggested levels vary, depending on machine design features such a s the clearance between the shell and washing cylinder, but general recommendations are: low water levels provide a ratio of four pounds of water (% gallon) for each p m n d of textiles, high water levels provide a ratio of six pounds of water (% gallon) for each pound of textiles. Many operators standardize suds and rinse levels a t 6 and 12 inches respectively a s measured from the bottom of the washing cylinder. For all-cotton loads, these levels correspond to a total quantity of water, both absorbed and free, of about 4:l for suds and 6:l for rinse levels. For 50/50 polyester/cotton loads, the levels are about 3:l for suds and 5:l for rinses because polyester absorbs less water. Here's a n example of how to convert ratios of total weight of fabric,/total weight of water to gallons of water and water levels: 1,600 pounds of water is required to achieve the 4:l suds level in a washer rated a t 400 pounds for cotton fabric; one gallon of water weighs 8.34 pounds; and 1/3 gallon of water is retained per pound of cotton. Therefore: 8.34 pounds x 113 gallons = 2.5 pounds of water reta~ned per pound of cotton 1,600 pounds of water/ 8 34 pounds per gallon = 192 gallons required 400 poundsof cotton goodsx 1/3 gallonsof water per pound of cotton = 133 gallons of water to saturate 192 gallons required - 133 gallons to saturate = 59 gallons of water to achieve desired level and suds ratio

The remaining 59 gallons of water produces the desired level in the machine. However, equipment differs among manufacturers, so specifications must be consulted to determine the proper level setting to yield a volume of 59 gallons taking into consideration the volume displaced by the saturated load. For most equipment, the level is five or six inches. Extractors

Extractors are designed to remove a large percentage of water from a washed . . load before further processing. Separate extractors are needed for conventional and batch washers only. There are two types: centrifugal units and hydraulic presses. Centrifugal or rotary extractors spin the water out of textiles a t high speeds. The extraction cycle of a washer/extractor operates in the same way. The load must be evenly distributed around the circumference of the extractor so t h a t it doesn't become unbalanced and cause the extractor to "walk." Speed and extraction time are determined by the temperature and fiber content of the load. Cool loads require longer extraction t h a n warm loads, that is, the hotter the bath prior to extraction, the more water removed during extraction. Hydraulic press extractors use either a diaphragm or a piston to squeeze water out of a fabric. The load i s reduced to a compressed "cake" for finishing. Diaphragm extractors can exert pressure of up to 600 psi (pounds per square inch) to the textiles. In one type of diaphragm extractor, up to 225 pounds of textiles are loaded into its flexible, one-piece molded diaphragm liner, which squeezes the load from all sides with hydraulic pressure. In one type of piston extractor, a 200-pound capacity tubis rolled into position over the piston. Hydraulic pressure forces the piston upward against the wet textiles, squeezing the water from the load. WasherJextractors

Washer/extractors are, a s the name implies, a combination washer and extractor. The cylinders are designed basically the same a s in conventional washers a s open-, split-, or Y-pockets. Multispeed motors or additional motors provide the high-speed cylinder rotation needed to extract a large percentage of the moisture that would otherwise be retained. A washer/extractor provides a number of advantages over a conventional washer: It eliminates the need for a separate extractor, which reduces requirements for floor space and labor. The extraction process markedly reduces the weight of the load, making manual unloading easier. The ability to use intermediate extractions during washing can reduce time, energy, and water requirements. For example, an intermediate extract between a cold or warm flush and a hot suds reduces the amount of energy needed to raise the water temperature, or a n intermediate extract during the rinse baths can eliminate a minimum of one rinse.

Tumblers

Tumblers or dryers consist of rotating cylinders through which heated a i r passes to remove moisture from clean textiles. The heated air is provided by steam or hot-oil coils; electrically heated coils; or a n open fire of natural gas, propane, or oil. The amount of drying that textiles receive in a tumbler depends on the type of finishing needed. Turkish towels, diapers, and other items are fully dried since the tumbler is the last and only piece of finishing equipment. Garments and linens are often only preconditioned for other finishing processes. Two key elements of efficient drying a r e the volume of the basket and the quantity of air passing through the load. Ironers and presses

Many of the textile items processed by a professional laundry require ironing or pressing a s a final finishing step. Flat items such a s sheets and pillowcases are routinely finished on roll-type flatwork ironers, and contoured items s u c h a s cotton wearing apparel are typically finished on presses. Normal flatwork ironer design consists of from one to 12 padded rollers i n contact with heated metal chests. Ironer pads are made of metal, aramid, or high-temperature nylon. The condition of the ironer pads is critical to obtaining a quality finish. Pads and covers must be replaced periodically to maintain the proper roll diameter and chest contact for optimum ironer performance and ironing speeds. The most common heat source for flatwork ironers is steam, although g a s and heated synthetic fluids are also used. T h e degree of dryness obtained from a flatwork ironer is determined by: the temperature of the chest, the pressure of the rollers against the chest, the speed a t which items pass through the ironer, the number of rolls on the ironer, the degree of contact between the rollers and the chest, and the nature and moisture content of the fabric being ironed. Utility presses used to finish wearing apparel and small flat pieces consist of a n upper unit called the head and a lower unit called the buck. The operator places the garment on the buck and closes the head. The head can be a polished metal surface or padded. Both buck and head a r e heated either by steam or electricity. Steam tunnels

Steam tunnels consist of a conveyor system t h a t transports garments o n hangers through a cabinet or tunnel equipped with steam and air jets. T h e steam tunnel's main function is to remove wrinkles while drying the garment. For maximum performance, the tunnel's temperature, humidity, and conveyor speed must be properly adjusted. Then, after leaving the tunnel, garments must be allowed to h a n g free until cool. Steam tunnels provide high-production finishing of durable-press garments a t a low per-piece cost. However, they can't do a quality job unless processing guidelines designed to eliminate wrinkling in permanent-press items are followed throughout the entire laundry operation. The tunnel or cabinet may n o t

be able to remove wrinkles set into garments by a n overloaded washer or a n overnight stay in a cart. Steam air finishers and specialized presses

Garments such a s pants and shirts are frequently finished on specialized presses, equipment called pants and shirt presses. These pieces of equipment use metal forms or inflated bags to hold the garment in the desired shape during drying to achieve the final finish. With body-form equipment, the operator places the garment over a form that i s inflated by a mixture of air and steam. In another method, polished, heated metal surfaces close on the garment, which h a s been placed on a metal form. This specialized equipment can make sharp creases a n d smooth waistlines a t a higher rate of production t h a n can universal presses. TUNNEL WASHING

Until about the mid-1950s, laundering was entirely a batch process in which soiled goods were sudsed with alkalies and surfactants, bleached, rinsed, soured, and finished in a series of baths drawn and dumped from the same machine. Then the need to conserve water, labor, a n d energy led to a search for a more efficient laundry process. I n Europe, where water and personnel needs were critical, the concept of the tunnel washer evolved. This concept h a s developed a t a rapid pace. --

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The development of continuous batch tunnel washers

The idea of producing linen in distinct batches or lots continuously and without pause for loading and unloading presented formidable engineering problems. The biggest problems were how to create distinct washing zones and provide efficient moisture extraction. The first attempts a t a continuous washing system evolved from the concept of water reuse. Engineers reasoned that the final rinse water in conventional batch processing should be suitable for the early stages of the washing formula. The high detergent concentration of rinse water is capable of suspending considerable amounts of soil. This principle is still employed i n plants t h a t reuse rinse water i n conventional equipment. The system reduces water consumption without extensive capital outlay. This notion t h a t rinse water could be reused in subsequent breaks led to the development of the first continuous water use arrangement. Engineers connected a series of conventional machines so that water counterflowed from t h e final rinse toward the washing zone. The goods remained in batches, but the fluid flowed continuously through the goods from clean to soiled. Today's tunnel washers represent the culmination of more than a quarter century of constant improvement. They are sophisticated material-handling devices that accomplish all of the steps in laundering a s merchandise flows into and out of the machine, virtually without operator intervention.

Textile handling systems for tunnel washers

Generally, tunnel washers are loaded automatically, either by a compartmentalized loading conveyor t h a t advances the compartments of textiles one a t a time on command from the tunnel, or from bags on a n overhead rail that open on command. Compartmentalized conveyors are normally available with up to 12 compartments. The operator loads the textiles into the lowest compartment of the conveyor a n d enters the classification into the tunnel's control system. The control system tracks the load a s i t progresses through the tunnel, adding chemicals a n d controlling temperatures a s needed in each chamber. Some loading conveyors include a weighing device to assure t h a t the management-mandated quantity for each soil classification is added to the conveyor each time. The controller is programmed with specific soiled load weights for each soil classification. Operators simply enter the classification into the controller, which automatically accesses a n d displays pertinent information on the system's control panel. The weighing systems often include audible and/or visual signals to guide the operator i n putting the right quantity in each compartment of the conveyor. Advantages claimed for compartmentalized loading conveyors over bag-onrail systems include lower initial cost and lower ceiling height requirements. Automatically opened bags on rails are also popular. With this system, soiled goods generally are loaded into bags in the sorting area. The bags are stored on one of several rails, usually according to the washing and/or finishing classification. The advantages claimed for bag systems are that they can store large quantities of prepared, separated soiled linen and they are more automatic t h a n conveyor systems. Types of tunnel washers

Tunnel washers are classified according to their method of moving water and textiles. Tunnel washers are either bottom-transfer or top-transfer machines. Both types of machines use the principle of counterflow. Counterflow means t h a t the textiles being processed and the water used for processing move in opposite directions. Soiled textiles enter one end of the machine. Fresh water enters the rinse zone a t a steady rate from the opposite end. I n bottom-transfer machines, the screw action of the cylinder design moves or transfers textiles from one chamber to thenext along the bottom of the washing cylinder. I n top-transfer machines, textiles from one chamber are lifted out of the water to the top part of the washing cylinder where they slide down into the next chamber. By nature of design, top-transfer tunnel washers always have double shells. I n these machines, the outer shell i s always stationary a n d contains the water and washing chemicals. The rotating inner cylinder contains the textiles and provides the mechanical action and transfer mechanism. Bottom-transfer machines can have either single or double shells. Load sizes

A significant difference between conventional and tunnel washers is in the

load factor. Conventional washer loads range from 5.2 to about 6.8 pounds per cubic foot of free space. Tunnel washer loads typically range from 1.2 to about 1.9 pounds per cubic foot. Much of the free space in the tunnel washer is located above the textiles and solution. The space is needed to accommodate the mechanics of transferring textiles from one washing chamber to the next. However, this low textile-to-cylinder volume ratio allows textile surfaces much greater exposure to the dynamics of the washing process and improves washing over conventional washing equipment. Mechanical action

Mechanical action in the tunnel washer differs from conventional washers and washer/extractors. Bottom-transfer tunnels rotate through a n angle typically 300 to 450 degrees. The rotation causes textile items to slide and roll over each other, providing a squeezing action that forces the washing liquid through the textiles. The chambers in a bottom-transfer machine are in the form of an Archimedean screw. When it's time to transfer a load, the cylinder, which has been rotating back and forth, now makes a further 360-degreerevolution. This forces the merchandise forward, discharging a load from the final chamber. Immediately after transfer, a new soiled load enters a t the feed end. In most top-transfer machines, the washing cylinder rotates 300 degrees (150 degrees in each direction). During transfer, the machine reverses, and the scoop side of the lifter picks up the load and drops it into the next chamber. At least one top transfer machine rotates constantly through 360 degrees and transfers the textiles by a sequential reversal of 360 degrees. Bottom-transfer tunnels must transfer all of the water with the goods. The dilution effect in these machines is accomplished entirely by counterflow. Toptransfer tunnels pick the goods out of the water as they are transferred, leaving up to approximately half of the total water in the chamber. Since top-transfer tunnels also use counterflow, their manufacturers claim a dilution effect greater than that for bottom-transfer tunnels. This leads to claims that fewer top-transfer chambers are required for the same output and quality. Sizing a funnel washer and scheduling loads

Two factors determine the size of a tunnel washer: the production requirements in pounds per hour and the number of chambers required to remove soil. Production capacity is determined by plant requirements or throughput. For example, to produce 2,000 pounds per hour in 100-pound batches, a plant needs to load, wash, extract, and dry 20 loads per hour or one load every three minutes. The number of chambers required in a tunnel washer is dictated by the heaviest soil classification to be processed. For example, in a tunnel washer with 11 chambers, three-minute loads yield a total formula time of 33 minutes. This time may be fine for processing heavier soil classifications but too long for lighter soil classifications.

Soil classifications must be carefully scheduled to achieve the maximum economies inherent in tunnel washing. In fact, processing all classifications from very light soil to very heavy soil in a tunnel may not be cost effective. One way to handle different soil classifications is to alter transfer times so that the machine processes lighter soils in a shorter overall time. Another solution is to maintain transfer time and raise or lower chemical levels, water temperatures, and/or water flow rates to meet the needs of each soil level. If different transfer times are used for different soil classifications, the tunnel will transfer a t the slowest rate dictated by the heaviest soil in the machine. For example, a tunnel washer transferring loads on a two-minute cycle for light soil and a three-minute cycle for heavy soil will transfer every three minutes if classifications are mixed, slowing production. A solution is to schedule production so that heavy soil is concentrated into contiguous loads and not scattered throughout the production period. If there is excess tunnel washer capacity, using the excess capacity for heavy soil classifications might be cost effective. Otherwise, washing heavy soil in conventional equipment is probably the best solution. Extractorsfor tunnel systems

Two basic types of extractors are used in tunnel systems: pressure and centrifugal. Pressure extractors or presses. Most pressure extractors have a flexible diaphragm or "membrane" that, when pressurized against the textiles, conforms to all thickness irregularities and applies a uniform pressure. Unit pressure applied to the textiles ranges from about 20 bar (290 psi) to 36 bar (522 psi). As of this writing, a t least one press employs a perforated, flat, rubber pressure plate that may not fully conform to irregular cakes but has the capacity to blow compressed air through the textiles during extraction to enhance moisture removal. The cost and availability of compressed air for this type of system must be considered. The amount of moisture retained in textiles after pressing depends on these factors: Itextile type and its water-retaining characteristics, Itotal quantity of water that must be pressed out of the textiles, Iresidual chemical content in the water retained by the textiles, Iwater temperature, Iunit pressure applied to the textiles, and Itotal time a t full pressure. Presses able to exert high pressures will extract more efficiently, although easy-care or resin-finished fabrics may require low pressures to prevent wrinkles. Most presses offer a multiple-pressure option that lowers pressures automatically for these fabrics. Since the amount of time a t full pressure is also significant, another frequently offered option increases the rate at which the membrane can be pressurized so full pressure is achieved more rapidly, thus increasing the time at full pressure. However, the time required to achieve full pressure also depends on the quantity of water that must be pressed out of the textiles. With all other factors equal, full pressure is achieved faster with polyester/cotton textiles

than with cotton because less water needs to be removed from the textiles. Presses are subdivided into two basic classes: single-stage and two-stage versions. Single-stagepresses have a single pressing station into which all textiles are transferred from the tunnel. All the water transferred with the textiles must be pressed out in the single stage. Two-stagepresses have two pressing stations, pre-press and main press. The tunnel transfers the textiles into a perforated pre-press shaping basket in which most of the water is pressed out and the goods are pressed into a cake. The cake then passes to themain press, whereit receives maximum pressure. Two-stage presses are further subdivided into two classes: stationary prepress shaping basket and moving pre-press shaping basket. In the stationary pre-press shaping basket design, the pressed cake is removed from the shaping basket and transported, unsupported, by a belt conveyor to its position under the main press. In the mouingpre-press shaping basket, the pressed cake is transported by the shaping basket to its position under the main press. The doors of the moving shaping basket then open to deposit the cake. Since the cake remains supported during transport, the manufacturers claim that this style leads to fewer press faults. Centrifugal-type extractors. Centrifugal-type extractors are most often used with small, short, low-production tunnels, generally 25 to 35 kilograms or 55 to 77 pounds of capacity. These tunnels use relatively longer transfer times of six to nine minutes per transfer or 6% to 10 transfers per hour. Centrifugal extractors require longer transfer cycles to receive the goods, accelerate, decelerate, and then eventually unstick and discharge the goods. To limit vibration, some centrifugals use vibration sensors that reduce rpms (and extraction effect) when unbalanced loads occur. When processing goods with a high percentage of polyester, centrifugals can remove more moisture than presses; but this advantage diminishes and may even reverse when processing goods with a high percentage of cotton. Resulting moisture retention in centrifugals is affected by: textile type and its water-retaining characteristics, W total quantity of water to be removed from the textiles, W residual chemical content in the water retained by the textiles, W water temperature, G force exerted at full extraction speed, and w total time a t full extraction speed. Textile handling afler extraction

Most tunnel systems use an automated material handling system to convey the extracted work to dryers or to "no-dry" or bypass stations if the extracted textiles don't need drying or conditioning. In post-sort plants, all the work generally is routed through a single dryer. Most post-sort plants are located in Europe. All goods are cycled through the tumbler a t the same rate and batch size a s the tunnel. The goods arepre-conditioned only a t this time, then sorted and sent to the appropriate full-dry or finishing area.

Most pre-sort plants, where the textiles are presorted into washing/finishing classifications, use an automatic shuttle handling system to deliver the textiles to the appropriate dryer or no-dry destination. Although single-cake dryers are popular in Europe, dryers capable of processing two cakes are usual in the U S . Two-cake dryers require a double-cake shuttle. Thecontrol system also must be able to recognize when two successive cakes are incompatible so that incompatible goods aren't intermixed in the same dryer. Also available are material handling systems that automatically deliver the textiles by belt conveyors or in bags-on-railsfrom the dryers and/or no-dry stations to the appropriate finishing stations. Optional ticket printers and/or CRT screens display customer, goods, and similar data a s each load arrives a t its destination. These systems have the advantage of providing production data for management. Drvers

Dryers must be capable of drying or conditioning merchandise without holding up the continuous wash cycle. The vast majority of tunnel washer installations are coupled with dryers capable of handling the flow of laundered merchandise coming to them with a minimum of delay. Automatic systems communicate specific drying cycle information to the appropriate dryer based on the goods classification and/or the size of the load. A system that has 25 transfers per hour of 100-pound loads produces 2,500 pounds per hour. Slightly more than four 200-pound dryers are needed to full dry all loads a t a full-dry cycle time of 20 minutes including loading, drying, cooldown, and unloading. However, for this setup to work, all loads must be processed in double batches and the batches must be allowed to unload without delay. 0; the other hand, only one dryer is needed to maintain system balance if all loads are to be conditioned only in double batches for four minutes including loading and unloading. Of course, sequencing identical class loads such as all conditioned or full dried consecutively for long periods of time may not be practical. In this case, loads must be scheduled taking into account conditioned versus full-dry work and the subsequent finishing station, unless post-drying sorting is used. Careful scheduling maintains the proper balance between tunnel and dryers so that both pieces of equipment are fully utilized a t all times.

GLOSSARY

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Abrasion resistance - Degree to which a fabric is able to withstand surface

wear a n d rubbing.

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Absorption -Ability of a porous solid to hold, within its body, gases or liquids. Acid dye - A type of dye requiring a n acid environment during application;

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Acid number (acid value) - The measure of the amount of free acid in a sub-

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used for dyeing animal fibers. stance; expressed a s the number of milligrams of potassium hydroxide required to neutralize one gram of substance. Activated carbon - Carbon specially treated to give i t the ability to attract and hold dissolved substances in drycleaning solvent. Adsorption -Taking up of a substance by a solid or liquid surface. Affinity- The attraction of one substance for another, a s a textile fiber for a dye. Agglomerate - To coagulate or bunch particles into larger masses. Air permeability - Ability of a fabric to allow air to pass through it a s determined by its porosity. Air permeability is a factor in the warmth of blankets, for example. Alkali -A substance that yields negatively charged hydroxide (OH-) anions in a water solution. Alkaline substances, when dissolved in water, produce a slick feel, turn red litmus paper blue, and give solutions a pH value greater than 7. Alkaline hydrolysis- A chemical process that uses alkaline materials to break down other molecular units. The term is often applied to chemical damage to polyester fibers caused by contact with a strong alkaline solution. Alkaline pressure-A measure of the alkalinity of a solution a s expressed by its percentage of sodium oxide content. Amine -A compound t h a t may be regarded a s a derivative of NH3 (ammonia) in which one or more of the hydrogen atoms h a s been replaced by hydrocarbon radicals. Anhydrous - Free from water, a s in anhydrous metasilicate. Aniline dye - A type of dye derived chemically from aniline or other coal t a r derivatives. Anionic - A class of surfactants t h a t ~ r o d u c e snegatively charged active

Antibacterial - A chemical agent t h a t is able to kill or retard the growth of a

bacteria. Antichlor

- Reducing chemicals used in rinse or sour baths to facilitate com-

plete removal of residualchlorine. They includesodium bisulfite, sodium thiosulfate, and proprietary antichlors. Antirnycotlc - Having the property to minimize thegrowth of mold or mildew. Antiseptic - A substance, generally applied to living tissue, that prevents or arrests the growth of microorganisms either by inhibiting their activity or destroying them. Anti-static - Able todisperseelectrostatic charges on a fabric and prevent buildup of static electricity. Aseptic - Free of microorganisms capable of causing infection. Aspergillusniger- A type of fungus responsible for thedevelopment of mildew in fabrics. Atmospheric fading (gas or fume fading) - Fading of some dyestuffs through exposure to certain gases given off during the burning of fuels. Basic dye - A type of dye capable of coloring silk a n d wool directly but requiring a n assistant on cotton. Although they produce a very bright color, such dyes are little used because of their poor fastness. Bentonite - A colloidal clay capable ofadsorbing largequantities ofan oily soil. Bichloride of mercury - Sometimes referred to a s bichloride or corrosive sublimate. A poisonous, corrosive salt of mercury used chiefly in pharmaceuticals and antiseptics. I t frequently attacks and tenders cottons a n d linens, and the damage does not appear until the textiles are laundered. Biochemical oxygen demand (BOD) - A measure of the amount of oxygen consumed in the biologicc: ,oce;s that breaks down organic matter in water. Large amounts of organic waste use up large amounts of dissolved oxygen, thus the greater the degree of pollution, the greater the BOD. Biodegradable - A substance subject to the process of biodegradation. Biodegradation - The decomposition of a natural or synthetic substance through t h e action of bacteria a n d other microorganisms in water with the assistance of sunlight and dissolved oxygen. Bleachbath (bleach suds) -The bath in which bleach is added a s the last detergency-promoting agent incorporated into the laundry formula. I n the past, this step h a s been referred to a s t h e bleach suds because a light running suds was taken a s the visual indicator t h a t the pH was correct. With the advent of low-sudsing synthetic detergents and the placement of flushes between break and bleach to lower alkalinity for correct pH a t the bleach, testing for bleach pH rather than using the visual presence.of suds is a necessity. Bleaching in the clear - Bleaching under conditions where minimal amounts of soil, chemicals, and other materials remain in solution. Bleaching intensity - The quantity, concentration, time, and temperature of bleaching. Bleed - To lose dye from a colored fabric during laundering or drycleaning; can be caused by improper cleaning methods, dye application, or excess surface dye. Body - The compact, solid. or firm feel of a fabric.

Boiling polnr - The temperature a t which a substance passes from the liquid to

the vaDor state.

Bolt - roll or length of fabric. Bonding - A process of pressing fibers into thin sheets or webs held together

by adhesive chemicals.

Borax - A weak and sparingly soluble alkali, known chemically a s sodium

tetraborate. Break (breaksuds) - T h e first wash chemical bath. In light- and medium-soil

formulas, all of the surfactantldetergent and alkali to be used in the entire formula is generally added to the washer in the break bath. The break is the single most important step in the laundering process from the standpoint of soil removal. Break compound - Any washroom supply used in the break or initial operation in the washing formula. Broadcloth-A fine, rich-looking. closely woven cotton fabric, usually mercerized. Most dress shirts are broadcloth. Brownian movement - A ceaseless movement of ultra-microscopic particles of colloidal nature, first observed by a n investigator named Brown. This movement is important in detergent processes a n d is exhibited by soap and other colloidal substances. Brush - To finish knitted or woven fabrics by raising a n a p on them with circular brushes. Buffer -Substance or mixture of substances that in solution maintains a con. s t a n t hydrogen ion concentration despite addition of comparatively large amounts of acid or alkali. Building - The use of an alkali to enhance thedetergcnt efficiency of a soap.(' detergent solution. Bursting strength - The pressure required to rupt,ure a fabric. Calico - A coarse, printed cotton fabric, usually made from low-grade cotton and heavily sized. Carbonate - An alkaline chemical salt in which carbonic acid is the neutralized acid. Carboxyrnethylcellulose(CsH701(OH)10CH~COOHJn - Used a s a surface-active agent. (See surfactant.) Carboy - A container often encased in a protective covering and usually used to hold from 5 to 15 gallons of a corrosive liquid. Carryover (carryover suds) -Acleaningstepin a laundry formula in which no supplies a r e added, but supplies previously added a r e retained for use. Catalyst - A substance capable of speeding up a chemical reaction. I t can be recovered practically unchanged a t the end of the reaction. Cationic - A class of surfactants that produces positively charged active ingredients when dissolved in water. Caustic potash - See potassium hydroxide. Caustic soda - See sodium hydroxide. Causticity- The amount of free alkali or hydroxyl ions liberated when alkaline salts are dissolved in water.

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Celsius Referring to a temperature scale in which the interval between the freezing poirit and the boiling point of water, under standard pressureconditions, is divided into 100 equal parts or degrees, so t h a t 0°C corresponds to 32OF and 100°C to 212°F. Indicated by the letter C after the stated temperature. Centigrade See celsius. Centrifugal force - The force t h a t tends to propel a thing or its parts outward from a center of rotation. Choelomium globosurn - A microorganism responsible for the development of mildew in textile fabrics. Charged system A method of cleaning, employing drycleaning solvent to which a quantity of detergent h a s been added for improved cleaning. Chelate To tie up or render certain substances inactive. Chelating agent A substance t h a t h a s the ability to tie up and render certain substances, such a s hardness salts and iron, inactive in water. Chemical oxygen demand (COD) A measure of the amount of oxygen required to oxidize organic and oxidizable inorganic compounds in water. The COD test, like the BOD test, is used to determine the degree of pollution in a n effluent. Chino A particular type of all-cotton, khaki-colored army twill made of combed two-ply cotton yarns. Chintz A glazed cotton fabric often printed with figures a n d large flower designs. Chloride of lime A low grade of calcium hypochlorite assaying 35 percent available chlorine. Chlorite 'l'he bleaching agent sodium chlorite. Chrome dye - A type of dye t h a t uses a chromium compound a s a mordant or assistant. Clarify- To remove foreign matter and soluble impurities from a solvent usually by distillation or filtration. Classify- To separate goods according to degree of soil and resistance of fabric and color to physical and chemical attack. Cleaning cycle -The total time consumed from the beginning to the end of a complete round of cleaning operations. Clearing agent A material added to lower the cloud point of a liquid detergent product. Cloud point The temperature a t which a nonionic detergent or wetting agent, in solution, tends to become cloudy with consequent decreased solubility and effectiveness. CMC See rarboxymeihy~ce~lulose. Coagulate -To clot or consolidate into a mass. The solidification of egg white by boiling is an example. Coalesce - T h e tendency for smaller droplets of a liquid to form one larger drop. In a good e m ~ ~ l s i ocoalescence n, does not occur. COG - See NOG. Customer-owned goods. Colloidal State of subdivision of matter in which particles of 100 mu (microns) are dispersed in a continuous medium.

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Color buildup - Accumulation of loose or nonfast dies a n d other coloring matter from fabrics in a cleaning solvent. Calorimeter - An optical instrument for measuring color intensity; used to evaluate and standardize a colored solution. Combed yarn - 11 cotton yarn t h a t h a s been subjected to a special combing operation to remove short fibers and impurities remaining after the carding operations. This added process produces finer, smoother, and stronger yarns. Compatible - Capable of being used in conjunction with other materials without loss of essential properties. Condensate - The purified substance, usually water or solvent, formed a s a result of a condensing or distilling action. Condense -To reduce from one state to another s t a t e with a denser form, a s steam to water. Also, to compress or compact. Condition - To prepare goods for ironing, pressing, or other finishing operations by running in a tumbler until desired moisture retention is reached. Construction-Thenumber of yarns per inch in warp a n d filling in a fabric; for example, 60 x 52 means 60 yarns per inch of warp and 52 yarns per inch of filling. Contact stain - A stain acquired by a textile touching a staining surface or another textile and picking up color. Corduroy - A coarse, durable fabric having a piled surface raised in cords, ridges, or ribs. Count - See yarn count. Counterflow- A concept in which textiles being processed in a tunnel washer and the water used for processing them move through the machine in opposite directions. Coupling agent -- A substance soluble in both water and in material to be emulsified; improves the stability of a n emulsion. Crease resistant - Refers to fabrics with high resistance to wrinkling or creasing and good recovery from wrinkling. Often obtained by chemical finishing a s in durable press. Cretonne - A drapery or slipcover fabric, usually printed, similar to chintz, but without the glaze. CRF Abbreviation for crease-resistant finish. Crimp -To apply a wavy appearance to a fiber or yarn by means of a twist or mechanical application. Crock - To rub loose dye off one fabric onto another. May also be a container for chemicals. Cross-infection An infection t h a t is acquired from a contaminated environment. Crowsfeet - Indistinct wrinkles in a fabric. Crystal - A physical shape or form of matter, always conforming to a definite geometric pattern. Crystalline- Being in the form of crystals. A material t h a t is not crystalline is amorphous. Culture - A growth of microorganisms on a nutrient medium; to grow microorganisms on such a medium.

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Cure - To set a resin finish in treated fabric by converting it to the insoluble

Disinfectant detergent - A chemical compound formulated to disinfect while

form by heat. - Fabrics such a s velvets, plush, or corduroy in which pile surface is produced by cutting yarns,either warp or filling, t h a t were originally woven in loop form. Damask- A type of fabric in which the figures are formed by contrast between warp and filling yarns. The figures appear reversed on the wrong side. Decompose - To break up into similar component parts by heat or chemical action; for example. the decomposition by heat of sodium bicarbonate into soda ash and carbonic acid. Degrease - To remove greases and oils from garments prior to laundering or drycleaning with detergent a n d water. Deleterious - Harmful or destructive, a s the action of strong acids on fabrics. Deliquesce - The a c t of a solid turning to a liquid due to the absorption of atmospheric moisture. Denier - The weight in grams of 9,000 meters of fiber or yarn. The lower the denier number, the finer the yarn. Density - A substance's weight per unit of volume. With dry products, it is generally expressed a s ~ o u n d per s cubic foot; with liquid products, a s pounds per gallon. Deodorize - T o destroy or mask odor. Deposit - To settle upon, a s lime soap on a washwheel. ksiccate -To remove moisture; to dry. Desize -To remove the sizing from textile fabric. Desizingagent- A compound t h a t h a s the capability of removing sizing from textile fabric. Some enzymes are excellent desizing agents. Detergent - A surface-active agent or a blend of chemicals containing surfaceactive agents t h a t concentrates a t all the surfaces in the washing zone and aids in the removal of insoluble foreign substances or soil from textile fibers. Dlafomaceous earth - The hard skeletal remains of microscopic plants called diatoms. Used in filter powder. Diffuse- To spread or penetrate rapidly throughout. Dilution - A process using water to remove suspended soil from the washer by lowering the concentration of soil in each successive bath. Dilution occurs with each drain and fill and is frequently monitored to evaluate the effectiveness of rinsing. For conventional washers, a s the water from each bath is dumped from the washer, soil is removed so t h a t the water in t h e next bath h a s to suspend less soil. Dilution depends upon the total amount of water in the washer for each bath a n d the amount of water retained by the load after draining. Dimensionalstability- Ahility of fabric to retain its shape and size after being subjected to wear, washing, and drycleaning. Direct dye - A typeof dye used primarily to dye cotton and rayon, for which i t h a s good affinity. Dirt - Foreign matter out of place such a s soil or stains. Disinfect (disinfectant) - To free from infection, usually with a chemical agent that destroys disease germs or other harmful microorganisms.

- To scatter finely divided particles in such a manner t h a t the individual particles are not visible to the naked eye. Distill - To purify a liquid. such a s contaminated drycleaning solvent, by boiling, condensing, and collecting its vapors. D.P. - Abbreviation for durable press. Drill - A stout twilled cotton fabric. Drip dry - See wash-and-wear. Dry side - Pertaining to cleaning or spotting agents t h a t dissolve in drycleaning solvents but not in water. Duck- A dense, heavy cotton fabric usually having two warp yarns woven a s one. Lighter weights used for service coats and uniforms, the heavier for tents, awnings, tarpaulins, aprons, and wherever unusual strength is required. Durable press - A long-lasting finish applied to textile fabrics to improve their crease and wrinkle resistance. Synthetic resins are normally used for this purpose and are usually applied to cotton fabrics or blends of cotton and polyester. Dye - Complex chemical coloring matter having a n affinity for textile fibers. Elasticity -The ability of fibers, yarns, or woven and knit fabrics to return to their original shape after being stretched. Electrolysls - A decomposition caused by a n electrical current. Electrolyte - A solution t h a t easily conducts electricity. Elongation - Lengthening or stretching of a textile fiber, yarn, or thread by a force applied to it. It is expressed a s a percentage of the original length. Emulsification - Method of dispersing one immiscible liquid in another. Enzymatic action - The splitting up of fats, oils, proteins, and sugars by enzymes. Enzyme - One of many complex proteins formed by living organisms t h a t are capable of increasing the speed of some decomposition reactions. Esterilication- A process of producing a n ester (-C-O-)by reaction of a n alcohol with a n acid. Eufrophicatlon-The process by which a body of water, such a s a lake, becomes rich i n dissolved n u t r i e n t s with consequent oxygen deficiency. Eutrophication may occur by natural means or by artificial means such a s contamination by fertilizers. Extensibility- Length gained by stretching a fiber, yarn, or thread to the breaking point. It is expressed a s a percentage of the original length. Fabric - A system of textile fibers produced first by building yarns a n d then weaving or knitting these yarns. Fabric softener - A chemical added to the washer duringor after thcsour bath for t h e purpose of improving the feel or hand a n d suppleness and reducing harshness of fabrics. Fadeometer - A standard laboratory device for testing the iastness of a colored fabric to sunlight.

Cut pile

it cleans.

Disperse

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Fahrenheit Referring to a temperature scale on which the interval between the freezing point of water a t 32'F and the boiling point a t 21Z°F,under standard pressure conditions, is divided into 180 equal parts or degrees. Indicated by the letter F after the stated temperature. Fast color A color t h a t when applied to a fiber will not fade or change shade by exposure to sunlight, washing processes, or body wastes. Felt - To shrink wool fabrics with accompanying interlocking of the fibers. Fllament A fine, continuous fiber, such a s silk, rayon, polyester, or nylon. Filler A material added to soap or other detergent t h a t does not improve its effectiveness under the conditions of use. Film - A thin coating, layer, or membrane. Colloidal films have a n important part in emulsification and adsorption. Flame retardant (flame resistant) Pertaining to fabric treated or impregnated to resist burning. Also a chemical compound capable of imparting flame resistance to fabrics. Flammable Capable of being easily ignited a n d burned. Flash point -The lowest temperature a t which the vapors of a liquid decompose to a gaseous mixture t h a t can be ignited. Flatwork ironer rolling The rolling t h a t occurs, under certain conditions, to the edges of flatwork when they pass through a chest-type ironer. Fluorocarbon A hiehlv volatile solvent similar to verchloroethylene except that it contains fluorine atoms in place of chlorine in its chemical makeup. Flush A high-level bath for a short period of time prior to the break or the bleach bath. Flushes generally are used for conditioning textiles before subsequent baths and for removing debris and loose soil. Foam/fwmlng agent A colloidal hen omen on involving a n air-liquid colloidal system. A material that increases the stability of this colloidal phenomenon. Fray To wear out due to rubbing or friction. Fugifive (color) A color t h a t h a s poor affinity for the fiber to which it is applied and h a s a tendency to bleed, run, or be washed away entirely. Fused fabric A resilient two-layer collar or cuff bonded together by a n intervening solid film of binder. Gas fade- To fade or to change color because of contact with g a s fumes in the air. Germicide Anything t h a t destroys germs (microorganisms); applied especially to agents t h a t kill disease germs. Gingham A yarn-dyed cotton fabric usually woven in checks or stripes. Globule A small drop of a liquid or particle of solid. Glyceride A chemical compound composed of fatty acids and glycerine. When reacted with strong, hot caustic, it forms soap and glycerine. GO-back An improperly laundered or drycleaned piece sent back for recleaning. Gravity (specltic)- The relative weight of a certain volume of a solid or liquid compared with t.he weight of the same volume of water. Gray Dull appearance of fabric color due to redeposition of soil or dye from wash water br solvent. Grease A general name for oily solids.

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Greige (gray) - Pertaining to fabric produced by weaving or knitting prior to dyeing, bleaching, or finishing. It usually contains sizing or other finishes that are subsequently removed. Grelge goods - Unbleached fabric, such a s unbleached muslin or sheeting. Gum - A sticky, viscous, water-soluble substance exuded from various trees and plants. The substance hardens when exposed to air. Hand - The feel of fabrics such a s soft, harsh, or hoardy. Heat-set - The stabilization of synthetic fabrics to prevent change in size or sha~e. Hemoglobin - The pigment of blood. I t contains 0.4 percent iron and is a common source of staining. High tenacify - Referring to yarn of high strength. Highlight A lustrous or shiny area appearing on the surface of a starched fabric. Humidify The amount of moisture in the atmosphere. Humidify (relative) -The percentage of moisture in the a i r a s compared with the total amount of moisture t h a t the air can hold a t the same temperature. Hydrate -To combine with water. Also, a chemical compound formed by the union of water with some other substance. Hydrogen - A colorless, odorless, tasteless gas; flammable and lighter than any other known substance. Hydrogenation - A process in which hydrogen is added to the unsaturated portion of fats or oils t,o make them more solid and resistant to oxidation. Hydrotrope - Substances t h a t act a s solubilizers and coupling agents for otherwise incompatible materials. They help overcome turbidity or stratification in aqueous solutions containing a sparingly soluble oil or solid. They also act a s cloud point depressors for light-duty liquids. Examples are sodium or potassium toluene sulfonate. Hygienic - Pertaining to the preservation of health. I t requires sanitary conditions. Hygienicallyclean -Although not a precise definition, one t h a t h a s received acceptance i s merchandise free of microorganisms in quantities capable of causing disease. Hygroscopic - Capable of absorbit:$ atmospheric moisture readily. Hymolal salt - The sulfated fatty alcohols derived from the higher chain alcohols and having soap-like properties. In vitro - Refemng to the testing of antibacterial properties "in glass," a s in test tubes, with no interfering material present. In vivo - Testing of antibacterial properties a s "in life" usage, in which practical contaminants and denaturants are present. Industrial clothing (fabrics) Clothing for wear in industry rather than for apparel and household use. Infection - Invasion by pathogenic organisms t h a t multiply and cause disease. Infectioncontrol chemicals Any chemicals used to prevent cross-infection. Infectious - Having the ability to transmit disease. Insoluble - Incapable of being dissolved.

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Interfacialtension - The surface tension existing betwcen two liquids or a solid and liquid t h a t keeps the liquids from mixing or a liquid from spreading on a solid. Soap lowers the interfacial tension between water and some soils and thus allows the soil to be flushed away. Iridescent - Pertaining to fabrics having contrasting colored warp and filling rams. Keratin - Principal constituent of cuticle, hair, hoofs, and feathers. Very rich in sulfur. Kier - A mechanical device i n which cotton fiber or fabrics a r e boiled out to remove the natural impurities. Kier boil - A treatment for t h e removal of deap-seated stains. T h e fabrics are boiled in a solution of alkalinedetergent a n d soap in a n open tank, preferably provided with a steam injector for continuous circulation. Laminated - Pertaining to fabrics composed of layers of cloth joined together with resin. Latent alkalinify - Alkalinity present in t h e water supply. Lecithin - An organic fatty material containing nitrogen and phosphorous found in practically all animal tissues and in somevegetable matter, chiefly the seeds. Level -The heightof the water or solvent inside thecylinder ofthe washwheel when the machine is loaded and in motion. Liberate - To set free, a s to liberate chlorine or oxygen in bleaching. Lime - Calcium oxide or hydroxide. Llnt - Short fiber produced a n d loosened by mechanical action or the action of chemicals in the cleaning process. Lipase A fat-splitting enzyme. Lubricant - A material added to some laundry products to help keep washer doors from sticking and/or to make fabrics easier to process during ironing. Luster -The shine occurring on or imparted to fibers, yarns, or finished fabrics. Mercerizing - A process in which cotton yarns are held under tension while being passed through a caustic soda solution. The resulting yarn is strong and lustrous. Micelle- A special grouping of a number of molecules of a chemical substance, such as detergent, held loosely together by chemical bonds. Mil - A unit, 1/1000 inch, used for measuring the diameter of textile fibers. Mild charge - L o w concentration of detergent in drycleaningsolvent; usually one-half to two percent. Mildewcide - A chemical agent t h a t is able to kill mildew-forming organisms. Mileage (solvent) -The number of pounds of clothing t h a t can be cleaned with one gallon of solvent. Mineral spirits - Petroleum solvent. Moire - Fabrics having a grain or wood effect produced during finishing. Moistureretention- Amount of moisture, usually expressed a s a percentage of textile dry weight, t h a t a load of laundry retains before or after a processing operation. Monofilament - A single-filament yarn.

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Mordant - A chemical agent applied t o a tcxtilefiber to improve the affinity of a certain dye for the fiber and make the color fast. Mote - A small impurity that may occur in cotton yarn, such a s a spcck of cotton seed or other impurity from the cotton plant. Moth repellent - Chemically treated to resist moth damage. Also, a chemical compound for treating fabric, usually wool, to render it moth repellent. Muck (filter) - The combination of insoluble soil, used solvent, and filter powder t h a t i s removed from the bags, screens, or tubes of a filter. Also called sludge. Muriatic acid - The commercial name for hydrochloric acid. Muslin A firm, plain, white cotton fabric used largely for sheeting. Nap - Fiber ends lifted from the body of a fabric to produce a soft, downy surface. Net A porous bag, usually constructed of cotton or nylon, to contain garments during the cleaning process. Neutralization - A chemical reaction in which a given quantity of a n acid, either mineral or organic, reacts with a chemically equivalent amount of alkali to form water and a salt. NOG - See COG. Not our goods. Nonlonic - A class of surfactants that produce no charged active ingredients when dissolved in water. Nonpathogenic - Not capable of producing disease. Nontoxic - Not poisonous; not capable of produciug injury or disease. Nonwoven - A fabric produced directly from fibers matted together instead of being spun or woven. Nutrient - A nutritious chemical element or compound; a s a n example, phosphate or nitrate absorbed by plants to promote growth. Onebath system -A drycleaning procedure employing a low concentration of detergent in which garments receive a single wash with no rinse.This is also referred to a s a single-bath system. One-shot - A built soap or built synthetic detergent t h a t is added to the washwheel, usually in a single dosage. Opaclfier - A substance t h a t imparts a white, uniform creaminess or lotion effect to a liquid detergent mixture. Optical brightener - A type of dye t h a t enhances the brightness of ccrtain fibers by converting invisible ultraviolet light to visible light. Common ingredients in almost all manufactured or compounded laundry products. Frequently added to some fibers during manufacture. Ozone - A highly active form of oxygen containing three atoms per molecule instead of the usual two. I t i s usually formed by a silent electrical discharge in the air a n d is used as a n oxidizing a n d deodorizing agent in the purification of water. Package dye To dye yarn wound on perforated spools or tubes p l a c ~ din a special dyeing machine containing the dye liquor. Also a small contamer uf concentrated dye. Packageplant- A plant doing a complete cleaning service with all work done on the premises.

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Pad - To impregnate fabric with dye liquor or other liquid by squeezing between rolls. Also, to impregnate with liquid for a special purpose, a s to pad mops with a dust control oil. Pad dye - To dye fabric by first passing i t through a trough containing the dye and then squeezing it between rollers to remove the excess. Pastel -Pertaining to light shades of color. Pathogen - Microorganisms capable of causing disease. pearl ash -Common name for potassium carbonate. I t is a n alkali t h a t absorbs moisture from t h e a i r readily a n d h a s approximately 77 percent of the neutralizing power of soda ash, which it resembles. Penetrate/penetrating agent To wet out a fiber completely. A surfactant can be considered a penetrating agent. Percale - A closely woven fabric, either white or colored, principally used for dresses, shirts, and sheets. Perchloroethylene - Tetrachloroethylene (C12CC12).Popular drycleaning solvent. Permanent linish -A finish applied to fabric t h a t retains its specific properties throughout the normal period of wear and maintenance. Permanganate (potassium) - A strong oxidizing agent frequently used in stain removal. Permeable - Able to be penetrated by fluids or gases. Perspiration - A body excretion containing salt, albumin, fatty acids, and other constituents. It may be acid or alkaline depending upon varying conditions. Petri dish - A round glass or plastic dish with a cover used for growing bacteria. Petroleum solvent - Flammable drycleaning solvent derived from petroleum products. Two main types are in use: 140°F,and Stoddard solvent with a flash point of a t least 100°F. pH -The term applied to a scale of values designating the degree of acidity or alkalinity of a solution. The pH scale runs from 0 to 14 with 7 representing a neutral state. Values greater t h a n 7 a r e alkaline. Values less t h a n 7 are acidic. Pharmaceutical - Pertaining to drug o r medicinal uses. A pharmaceutical grade of chemical is suited to ~ h a r m a c e u t i c a use. l Photometer - An optical instrument for measuring the light reflectancy of surfaces. Used in determining whiteness, soil removal, and color fading for laboratory control of cleaning formulas. Physical - Pertaining to a n y properties or forces not chemical. Pick One filling thread on the loom or in the finished fabric. Pigment - Coloring matter that, in general, h a s no affinity for a surface. For example, t h e pigments in paint have n o affinity for wood. but they have a n affinity for oil. Dyes, on the other hand, have a n affinity for fibers. Pile - A fabric made with y a r n s or fibers t h a t stand upright from the main body of the material, such a s velvet. These may be looped a s in terry. Pill - A small ball of fibers on the surface of a fabric caused by abrasion and wear.

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Pineoil - A byproduct of the steam distillation of pine stumps in the manufacture of turpentine and rosin. It is used a s a solvent and deodorant. Ply- Yarn formed by twisting together twoor more single strands or threads. Polyethylene - A ~ l a s t i film c of high molecular weight; polymerized ethyline produced by polymerization a t high pressure. I t is translucent, is the lightest of all plastics, and remains tough and flexible even a t low temperatures. Polymer - The molecular chain-like structure from which resins a n d synthetic fibers are produced by the linking together of molecular units called monomers. Palymerize- To link molecules together to form a polymer. Pony washer Any small washwheel. Usually used for special pieces or s ~ n a I I l o t . needing careful treatment. Poplin - A ribbed fabric, usually cotton. Pore - The opening or space between yarns in a fabric t h a t produces "breathing" properties. Also may refer to spaces between fibers in yarns. Porous (porosity) - Having minute openings t h a t permit t h e passage of air or liquid through a material. Post-cure The application of heat to set permanent press resins after the garment h a s been completely manufactured. Potash - Common term for potassium and its compounds. Potassium hydroxide (KOH) A strongly alkaline chemical used chiefly for making soap and a s a reagent in chemical titrations. Precipitate - To separate, a s a solid from a liquid. Also refers to a s o l ~ d substance separated from a liquid. Pre-shrunk - Term used to describe fabrics or garments that have becn subjected to a shrinking process before being placed on the market. Pre-spot- To apply a cleaning or spotting compound to fabric spots or stains before cleaning. Pressure (detergent or alkaline) The total amount of alkali present for detergent use. Primary treatment - First stage of sewage treatment t h a t involves settling out larger suspended solids by screening and sedimentation before discharge for further treatment. Print A general term for fabric with designs from dyes applied by engraved rollers, wood block, or screens. Pure finish - Finish in which no sizing or treatment is added to the fabric. Quality control Testing a n d inspecting materials during manufacture or processing to assure conformance to quality standards. Quat (quaternary ammonium compound) Derivative of ammonium hydroxide or its salts in which nitrogen is bound to four replaceable groups (usually organic mdicals). Reagent Any substance used in a chemical reaction to detect, measure, examine, or produce other substances. Reclaim -To recover for further use, a s stained fabrics in a laundry. Also, to recover solvent from drycleaning garments by condensing the vapors driven off during drying. Also, recovering wash water for treatment and/or subsequent reuse.

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Relative humidity (solvent) - The amount of rnoislure present in drycleaning solvent expressed a s a percentage of the maximum amount t h a t the solvent could contain a t the same temperature and pressure. Repel - To force away from or prevent from mixing with or adhering to a s a chemical agent to repel soil from fabrics. Repellent - A chemical or substance that repels. Residue - The nondistillable matter remaining behind after solvent distillation. Resllient - Referring to the ability of fabrics to withstand crushing or creasing without objectionable change in appearance or shape. Rlnse - High water-level bath or baths following the bleach and preceding the sour or finishing bath. During rinsing the final portions of loosened soil are removed along with the bulk of the washing compounds used in laundering. Except for antichlors, chemicals are usually not added to rinse. Rinse solvent - Solvent used for rinsing garments. Rosin - An acidic material obtained from coniferous or pine trees; sometimes used to extend soap. Rosin soap - A soap made from rosin-containing material. Salt - Chemically, the product of thereaction between a n acid and a base. Also, sodium chloride (common table salt, brine). Sanforizing - T h e trademark for a patented process for pre-shrinking cotton fabrics by controlled compression during manufacture. Articles made from properly Sanforized cloth are not subject to appreciable shrinkage. Saponification- Alkaline hydrolysis of a n oil or fat, or the neutralization of a fatty acid to form a soap. Saturate - To charge or furnish with something to the point a t which no more can be absorbed, dissolved, or retained. Scour -To clean fibers or fabric to remove such impurities a s sizing, oil, and dirt in preparation for dyeing or bleaching. Secondary infection - A super-imposed infection occurring in a host who is already suffering from a n earlier infection. Secondary treatment - The biological treatment of sewage wastes following primary treatment by sedimentat~on. Selvage - The natural edge of a woven fabric finished so t h a t it will not ravel. I t always runs parallel to the warp threads. Semicolloid - A particle having only partial colloidal characteristics. Sepsis Poisoning caused by absorption into the blood of pathogen~c microorganisms. Septic Causing sepsis or putrefaction; infective. Sequester - A chemical process in which a soluble complex is formed that prevents the normal react~onof certain chemical species, for example, the action of water hardness ions i s sequestered by complex phosphates. Shakeout - To straighten out cleaned goods prior to finishing. Shrinkage -The contraction and increase in density of fibers and yarns causing a change in shape and size of textile fabrics. Moisture, sudden temperature changes, fabric design, and mechanical and chemical actions promote shrinkage.

-

Silica - A substance known chemically as silicon dioxide; sand is reprcsenta. tive of silica. Silt - A very fine suspension of mineral matter, usually found in water. Silver nitrate - A corrosive chemical t h a t causes black silver stains on textiles. Sizing Starch or synthetic polymer added to fabric to increase the firmness or crispness of the fabric. Slippage - A form of textile damage that results when one set of threads slips over the opposite set. Smooth natural fibers, yarns possessing little twist, fancy weaves (floats), and wear are common causes of slippage. Slub-A thick placein a yarn thatproducesan irregularity in the fabric. Filling yarns are sometimes dubbed purposely to give a n irregular ribbed effect to the fabric. Sludge - See muck. Also a concentrate in the form of a semi-liquid mass deposited a s a result of the treatment of sewage and industrial wastes. Snap The quality of a finished fabric when it possesses luster, uniformity, and unimpaired whiteness. Sodium hydroxide (NaOH) - A strongly alkaline compound used in making soaps and alkaline builders. Soil release - A finish applied to textiles designed to provide easy removal of subsequently applied soil. Soil repellent See soil retardant. Soil retardant -Treated to resist soiling. Also, achemical substance that, when applied to fabric, will enable it to resist soiling. Soluble - Capable of being dissolved in water or solvent. Solvent - A substance, usually liquid, capable of dissolving other suhstances. I t is the name usually given to the liquid used for drycleaning garments. Solvent (140°F) - See petroleum solvent. Solvent retention - Amount of solvent that a load of drycleaning retains after cleaning and extraction. Sour - An acidic agent used in the final bath of the laundering process to neutralize the last traces of alkali from soaps and builders left in fal~ricsfrom previous steps in the process. Sour bath - Normally the final bath in the laundering process. The purpose of the sour (or acid) bath is to neutralize the alkalinity of the water in the textiles before removing them from the machine for finishing. Specific gravity - The ratio of the weight of a definite volume of a given substance to the weight of a n equal volume of water. Temperature must be specified. Split rinse - A rinse of moderate temperature obtained by complrtely opening both hot and cold water supply valves a t the same time. Spot - To treat by hand a spot or stain with a chemical for the purposeof removing it. To ~ o s i t i o nthe washwheel for openingAoading. Squeeze roll - A mechanical device for applying pressure to squeeze out liquid.

-

-

-

Staple-Theaveragelength of a raw textile fiber t h a t is twisted into a yarn. I t may vary from one-half inch as in the case of cheaper cottons to many miles in length a s in the case of rayon filaments. I n general, when comparing natural fibers of the same type, the longer staple is of higher quality a n d is stronger. Starch lubricant - An oily o r w a x y m a t e r i a l added t o s t a r c h t o i n c r e a s e flexibility. Sfatic electricity - An electrical charge generated by rubbing unlike bodies together. Sfeam sweep -The injection of wet steam to the still, just above the liquid solvent level, to help flush out the solvent vapors. Stearine - A glyceride composed of a stearic acid and glycerine. When tallow cools from a melted condition, stearine is the first material to solidify. Sterile - Free of living organisms. Stocksolution - A solution of laundry or drycleaning supplies prepared in concentrated form for later convenient use. Stop spot - To spray, splash, or pour a soil-spotting compound on apparently heavy or tenacious soil stains prior to cleaning. Straight s o a p - Commercially pure soap containing a t least 88 percent anhydrous soap. Streak- A stain taking the form of a line on a drycleaned garment caused by the nonvolatile residue in highly contaminated solvent. Strength, breaking - See tensile strength. The force required to cause fabric breakage. Strip - To remove dyes or stains from fabric by use of a chemical reducing agent. Stripper (stripping agent) -The agent used to strip dyes or stains from fabrics. Strong c h a r g e - High concentration of detergent in drycleaning solvent, usually about four percent. Substantive - Self-combining or adhering tenaciously, a s a dye substantive to cotton. Suds - A bath occurring between the break and bleach bath. Suds baths are carried out a t low water levels, usually with hot or tempered water. If alkali or detergent isn't added on these additional suds baths, they are referred to a s carryover suds. Suds carryover - See suds. Sulfur black - A black dye t h a t is f a s t to washing but very sensitive tochlorine bleach. Sulfur dioxide- An irritating, gaseous compound of sulfur found frequently in the atmosphere. I t is capable of causing dye fading and fabric tendering when in contact with moisture. Sulfur dye - A type of dye having sulfur in its basic structure; h a s poor bleach resistance. Sunfast- Fabrics colored with dyes t h a t will not fade under normal exposure to sunlight. Supersafurafe -To cause to contain more dissolved matter in a solution than is normally possible. Such solutions are unstable and readily return to t h e saturated state.

Surface tension - T h a t property of all liquids in which the ex1,osed surface tends to contract to the smallest possible area, namely a sphere. This tendency is greatly reduced by detergents, which aid i n t h e wetting a n d removal of soil from fabrics. Surfactant (surfaceactive agent) - A substance t h a t alters energy relationships a t interfaces, such a s wetting agents and foaming agents. Suspended solids (SS) - Small particles of solid pollutants in sewage t h a t contribute to turbidity and t h a t resist separation by conventional means. The examination of suspended solids and the BOD test constitute the two main determinations for water quality performed a t wastewater treatment facilities. W a l e - A stain t h a t exhibits a wavy outline. Syndet - Shortened form of synthetic detergent. Synthetic detergent - A surface-active material made from synthetic organic compounds that h a s cleansing action similar to soap. These detergents may be anionic, cationic, or nonionic, depending on their constitution. Synthetic solvent - A nonflammable chlorinated or fluorinated drycleaning solvent such a s perchloroethylene. Tenderize (tender) - To lower the fiber strength of fabric by chemical or mechanical me:ms. Tenslle strength - The measure of the ability of a yarn or fabric to resist breaking. Tertiarytreatment - A phase of wastewater treatment beyond the 85 to 95 percent BOD removal of the secondary stage by such processes a s carbon adsorption, reverse osmosis, ion exchange, and demineralieation. Tetrachloroethyiene - See perchloroethylene. Texfile-The construction of yarns or knitted or woven fabrics. Thermoplastic - Having the property of becoming soft under application of heat, specifically referring to certain synthetic resins and textile fibers. Thermosetting - Having the property of hardening or setting with heat a s do certain plastics or synthetic resins. Thixotropy -The property of a substance decreasing in viscosity upon agitation and increasing in viscosity on standing after agitati0n.Thi.s term is encountered mostly in soap stock tanks. Titanium stripper - A chemical reducing agent containing a compound of titanium used for dye or stain removal. Titanous chloride (Tic!,) - A compound of titanium a n d chloride t h a t is a n active reducing agent. I t is strong enough to remove m a n y dyes and is used a s a stain remover. Titration - A process used to measure the concentration o r amount of a chemical present in a solution. Tolerance - Ability to withstand or endure without ill effects. Top dye - To add color to a fabric t h a t h a s already been dyed to produce a greater depth or a change of shade to match the desired standard. Total fatly acid (T.FA) - The total amount of fatty material t h a t is obtained when a sample of f a t or fatty acid i s completely saponified and, after acidulation, extracted with petroleum ether or ethyl ether.

Translucent - Allowing passage of light, but diffusing it so that objects beyond cannot be clearly seen; in between transparency and opacity. Two-bath system - A drycleaning system utilizing two distinct cycles in the cleaning process, one with solvent containingdetergent, the other with clear rinse solvent. Vapor- A gas, especially from a substance t h a t is a solid or liquid a t ordinary temperature. Vat dye - An extremely light and wash-fast type of dye applied to fibers in a soluble form by reducing action and then permanently set by oxidizing to its original insoluble form. Used primarily on cotton yarns and fabrics. Verdigris - A greenish or bluish deposit of copper soap or salts formed on copper, brass, or bronze surfaces. Viscosity - The resistance to flow exhibited by a liquid product. Viscosity in detergent practice is measured in centipoises, water a t room temperature having a viscosity of 1 centipoise. The higher the viscosity, the thicker (less fluid) the product. Viscous - Possessing or characterized by viscosity. Volatile - Readily evaporated. Volatile matter - T h a t portion of a chemical substance t h a t vaporizes below a specified temperature within a specified length of time. Warp - The h e ~ v yyarns running lengthwise (parallel to the selvage) in a fabric and upon which the cross yarns or filling yarns are built. Wash-and-wear - Fabrics or garments treated with a wrinkle-resistant finish allowing them to be washed and used without pressing. Washing s o d a - A form of soda a s h containing crystallized water within its molecular structure. Washwheel - A washing machine. Water conditioning -The treatment of water prior to washing to remove undesirable, suspended, or dissolved matter. Water repellent - Referring to fabric or garments treated to resist wetting by water without closing the fabric pores. Also, a chemical used to impart water repellency to fabrics. Waterproof - Referring to fabrics t h a t have been treated in such a manner a s to make them impervious to penetration by water. Rubber, oil, or plasticcoated fabrics are typical. Weight - T o apply a finish to fabric to give increased weight. Wet - To cover or saturate with water or solvent. Wet clean - To clean by washing in water. Wet-dry - Pertaining to spotting agents that are soluble or miscible and rinseable in both water and drycleaning solvents. Wet-side- Pertaining to detergents orspotting agents that aresoluble and rinseable in water. Wetting agentlwetting - A material that increases the spreading of a liquid medium on a surface. Whiteness retention - The whiteness reflectance of a laundered or drycleaned fabric expressed a s a percentage of the original reflectance. Yarn - The continuous thread-like strand resulting from the spinning operation and used for weaving, knitting, or crocheting.

Yarncount-Thenurnber ofyarns per inch used in the construction of a fabric. Zeolite - A hydrous aluminum-sodium silicate capable of exchanging sodium for calcium magnesium a n d other metal. It also h a s the capability of regenerating (reversing) itself when treated with brine(concentrated sodium chloride solution). Zero son water - Sometimes called "zero hardness? This refers to water tha t is free from hardness salts.

APPENDIX 1: WEIGHT OF TEXTILE RENTAL ITEMS For production scheduling a n d control, particularly in washroom a n d drying operations, it is important to know unit weights of items processed. T h e TRSA Weight C h a r t lists weights of most items served by textile rental companies. T h e chart is to be used a s a guide. Each plant should develop its own weight c h a r t because of variations of fabric type a n d weight, item size, styling, a n d different item mix a n d process loads. T h e average weight reported is a "weighted average" from all of the surveyed textile rental companies. T h i s means t h a t t h e average could move to the higher weights or lower weights reported, depending upon the number of items a t t h a t weight. A s a n example, suppose five plants ( A , B, C, D, a n d E) each weighed a different number of the s a m e sized towel.Thcy might h a v e reported a s follows: Planf

a

' t

Number weiahed

T&l weiaM

Weight per towel

WelgM per 100 towels

Toobtain t h e weighted average, the total weight (86)would be divided by the total number of towels weighed (100) a n d then multiplied h y 100. I n t h i s case, t h e answer would be 86 pounds per 100 towels. T h e weighted average falls between P l a n t A a n d P l a n t B because P l a n t A accounted for 50 percent of the towels weighed. T h e average weight is arrived a t by dividing the total welght per towel (3.73) by the number of additions (5) a n d then multiplying by 100 t o a r r i v e a t average weight per 100 towels - 74.6 pounds per 100 towels T h i s average i s almost den tical with the weight per 100 towels of t h e middle plant reporting (C). TRSA uses the "weighted average" instead of the average weight because it more accurately represents the influence of each towel weighed. 183

FIGURES: F i g u r e 1-1: Acidity and alkalinity of water solutions ...................... 14 F i g u r e 1-2: pH of increasing alkaline solutions ............................ 15 F i g u r e 2-1: Base-ion exchange (zeolite or resin) ............................ 31 F i g u r e 2-2: Backwashing of base-ion exchange water softener.. .......... 32 F i g u r e 2-3: Regeneration of resin (zeolite) with brine ...................... 32 F i g u r e 3-1: Surfactant molecule schematic ................................. 36 F i g u r e 3-2: Orientation of surfactants in oil a n d water ................... . 3 6 F i g u r e 3-3: Oily surfactant complex ........................................ 37 F i g u r e 3-4: Dirt and oil imprisoned in textile.. ............................. 37 F i g u r e 3-5: Surfactant penetrating oily soil ................................ 38 F i g u r e 3-6: Surfactant dispersing oily soil.. ............................... . 3 8 F i g u r e 3-7: Oily soil lifted from textile.. ................................... . 3 9 F i g u r e 3-8: Soap (sodium stearate). ......................................... 40 F i g u r e 3-9: Nonionic, condensate of ethylene oxide with a fatty alcohol . . 42 F i g u r e 3-10: Nonionic, condensate of alkyl phenols with ethylene oxide .......................................................42 F i g u r e 3-11: Buffering effect of alkali, solutions of industrial alkalies containing 0.2% N a z O . . ........................... 46 F i g u r e 6-1: Nonmercerized cotton.. .........................................75 F i g u r e 6-2: Mercerized cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75 F i g u r e 6-3: Flax (linen) ...................................................... 76 F i g u r e 6-4: Bright nylon.. ................................................... 77 F i g u r e 6-5: Low-modification ratio trilobal nylon, 15 denier per filament, bright luster ..................................... 77 F i g u r e 6-6: Low modification ratio trilobal polyester, 1.4 denier per filament, semi-dull luster.. ................................ 79 F i g u r e 6-7: Cuprammonium rayon, 1.3 denier (0.14 tex) per filament, bright luster ................................................80 F i g u r e 6-8: Viscose rayon, regular tenacity, bright ........................ 80 F i g u r e 6-9: Fiber shapes from the spinneret ................................ 82 F i g u r e 6-10: Blending of cotton and polyester fibers.. ..................... 83 F i g u r e 6-11: Plain weave fabric.. ...........................................84 F i g u r e 6-12: Right-hand twill weave fabric (2x2) . . . . . . . . . . . . . . . . . . . . . . . . . . 84 F i g u r e 6-13: Herringbone twill weave fabric . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 F i g u r e 6-14: Satin weave fabric.. ........................................... 85 F i g u r e 6-15: Comparison of weft and warp knit stitches.. ................ 86 F i g u r e 6-16: Types of stitches and structures .............................. 87 F i g u r e 6-17: Basic garment finishes for permanent press ................. 8 8 F i g u r e 7-1: Closed-oil mop washing system .............................. . I 1 1 F i g u r e 8-1: NFPA hazardous material code with numerical scale.. ..... .123 F i g u r e 11-1: Open-pocket washwheel.. ................................... .152 F i g u r e 11-2: Split-pocket (Pullman) washwheel .......................... .I52 F i g u r e 11-3: Y-pocket washwheel ..........................................152

ACKNOWLEDGMENTS

The authors gratefully acknowledge the Production and Engineering Committee of the Textile Rental Services Association of America for sponsoring t h e preparation of this text. The time and guidance provided by the members of t h e Textile Laundering Technology Task Force proved to be a n invaluable contribution to the accuracy of the manuscript for this book. The authors also acknowledge Lucie Chapman, Tin York, and Frances Romero for their expert technical assistance in the preparation of this book manuscript.

PRODUCTION AND ENGINEERING COMMITTEE The Textile Rental Services Association of America gratefully acknowledges the contribution of each of the following committee members: M a r c Drolet,* chairman, Crystal Laundry, Manchester, N.H.; S a m B a n k h a l t e r , G & K Services, Inc., Minneapolis, Minn.; B a r b a r a B a r n e s , Diversey Wyandotte Corp., Wyandotte, Mich.; K r i s Bloniarz, Federated Linen & Uniform, Brooklyn, N.Y.; R i c h a r d W. Borgmeier,* Steiner Corp., Salt Lake City, Utah; R o b e r t Brill, Republic Linen Supply, Los Angeles, Calif.; D o n a l d H. B r o w n l e e , Ellis Corp., Itasca, Ill.; B e r n a r d C. Bulgrin, Morgan Services, Inc., Chicago, Ill.; R o b e r t Capece, Val-Chem Co., Inc., Sayre, Penn.; J o h n P. Ciambrone, Allied Management Consultants, Inc., Long Branch, N.J.; R o g e r F. Cocivera,* Penn Linen & Uniform Service, Inc., Allentown, Penn.; C h a r l e s T. Cooper, Cooper Laundry Machinery Co., Denver, Colo.; W B e r n a r d P. C r a m e r , Forest City Linen Supply, London, Ontario, Canada;

IEd Curran, C & W Equipment Co., Cincinnati, Ohio; IHenry J. Dokter,* Aratex Services, Inc., Schaumburg, 111.;

Jody S. Edwards, Domestic Textile Services, Inc., Wichita, Kas.; IJoe Eubanks, Unitog Rental System, Minneapolis, Minn.; IYork Feitel, Milliken & Co., Spartanburg, S.C.; IRaymond Goding, Federated Linen & Uniform Supply, Brooklyn, N.Y.; IJim Haried, Energenics, Inc., Naples, Fla.; IRoger D. Harris, Metro Linen Services, McKinney, Texas; IJ a n Hennekes, Brim Laundry Machinery Co., Dallas, Texas;; IDaniel M. Hertig, G.A. Braun, Inc., Syracuse, N.Y.; 8 Richard Johnson, White Rose, Inc., Memphis, Tenn.; 8 Robert 0. Kaloustian, Morgan Services, Inc., Chicago, Ill.; ICharles P. Keith, Jr.,* Keith Associates, Acworth, Ga.; 8 Lee R. Kemberling, Kemco Systems, Inc., St. Petersburg, Fla.; IKenneth L. Koski, Initial USA, Atlanta, Ga.; IGregory J. Kramer, Textile Care Div. of Ecolab Inc., St. Paul, Minn.; IRoger K. McMillan, Colmac Industries, Inc., Colville, Wash.; IRudolph A. Maglin,* Diversey Wyandotte Corp., El Toro, Calif.; IJ o s e f Mayer, United Service Co., Youngstown, Ohio; IEdward K. Murphy, EKM Mangement Services, Inc., Atlanta, Ga.;

Woody Ostrow, Clean Textile Systems, Pittsburgh, Pa.; August J. Palmieri, Associated Textile Rental Services, Utica, N.Y.; ID. J a m e s Paradee, Shared Hospital Services, Portsmouth, Va.; INorvin L. Pellerin,* Pellerin Milnor Corp., Kenner, La.; IJ o h n Potts, Milliken & Co., Spartanburg, S.C.; IDonald L. Proudman, Automatic Control Systems, Inc., Taunton, Mass.; ILeonard Reino, Reino Linen Services, Inc., Gibsonburg, Ohio; IMu1 Rigby,* Milliken & Co., Spartanburg, S.C.; IBradley Shames, Republic Linen Supply, Los Angeles, Calif.; IJ o s e p h C. Sherrill,* Sherrill Associates, Homewood, 111.; IRoger C. Simpson,* National Linen Service, Atlanta, Ga.; IMike Spence, Faultless Linen Supply, Kansas City, Mo.; ILouis J. Spirio, American Service Corp., Miami, Fla.; ITed C. Stephens,* Largo, Fla.; IThomas D. Storm,* Fabrilife Chemicals, Inc., Cincinnati, Ohio; IDonald L. Struminger,* Virginia Linen Service, Petersburg, Va.; IJ a m e s H. Surridge, Fabrilife Chemicals, Inc., Cincinnati, Ohio; IWilliam J. Tingue, Tingue, Brown & Co., Englewood, N.J.; 8 Timothy E. P. Topper, Topper Linen Supply Limited, Toronto, Ontario, Canada; IWilliam T. Twitty, Jensen Corp., Fort Lauderdale, Fla.; 8 H a r r y C. Ward, Wardco Systems USA, Pipersville, Penn.; 8 David Wayne, Wayne Towel & Linen Supply Co., Kansas City, Mo.; IA.D. Wilson, 11, Uwanta Linen Supply, Inc., Wheeling, W. Va.; IPeter Wolfe, Jensen Corp., Fort Lauderdale, Fla.; IClyde E. Blaco, Staff Liaison, Textile Rental Services Association, Hallandale, Fla.

i I i

1

'denotes members of Textile Laundering Technology Task Force

1i

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8

INTRODUCTION This book was written by Charles L. Riggs, Ph.D., professor and director of detergency research a t Texas Woman's University, and Joseph C. Sherrill, Ph.D., consulting chemist and engineer. I t explains the roles played by t h e different types of chemicals used in thelaunderingprocess and their effects on the textiles being laundered. The book can be used in two ways: a s a text for the student of laundering operations or as a reference book. Material is arranged for easy use by those looking for answers and solutions to both technical and nontechnical questions and problems. The material begins with an explanation of the basics of the laundering operation, laundry chemistry, and water characteristics. Chapters cover surfactants; the chemistry of alkalies, bleaches, and sanitizers; sours and softeners; mildistats and bacteriostats; and other washroom compounds. Steps in washing are described from soil sorting through extraction. Operational guides for each step in the process are followed by laundry formulas for various levels of soil. Various types of washing and finishing equipment currently available a r e described as well as textile fibers, fabrics, and finishes. Building on the previously presented material on chemistry and textiles is a chapter on textile damage. Another chapter discusses the ecological aspects of laundering a n d the need for conserving water and energy. The sections in the appendix a r e comprehensive and may become one of the most widely used portions of t h e book. The text can be used by plant managers, washroom supervisors, and laundry technicians interested in achieving effective laundering operations while, a t the same time, striking the necessary balance between minimum costs and a desired quality level. Technical material has been included only when necessary to enhance the reader's understanding of the practical aspects of laundering and its effect on textiles. This volume represents the fourth text published by the Textile Rental Services Association of America (TRSA) on the subject of textiles and laundering chemistry. In 1952,TRSA (then LSAA) published Laundering Chemistry wri tten by Pauline Beery Mack and Joseph C. Sherrill. In 1962, TRSA published

TRSA weigh1 chart

Weight in pounds of 100 clean, dry pieces Weighted Range of weight average reported

Weight In pounds of 100 clean, dry plseas WeigMed Range of wdgM average reported Law

BIB

DUST CONTROL

- 100%cotton - 65% polyester/35%cotton - 50%polyester/50%cotton

DUST MOPS 100%cotton 100%cotton 50% polyester/50%cotton 100%cotton 50% polyester/50% cotton 100%cotton 100%cotton 50% polyester/50%cotton 100%cotton 100%cotfon 50% polyester/50%cotton 100%cotton

FOUR-WAY

- 65% polyester/35% cotton - 50% polyester/50% cotton MECHANICS - 100%cotton SHOP, DENIM - 100%cotton - 50%polyester/50%cotton

TEA. WAITRESS - 100%cotton

ENTRANCE MATS 2'xJ' - cotton/lotex - synthetic/nrbber 3'x4' - syntheticlrubber 3'xS - cotton/lotex - syntheticlrubber J'xlO' - cotton/lotex - syntheticlrubber 4'xb' - cotton/lotex - syntheticlrubber 4 x 8 ' - cottonllotex - syntheticlrubber 9x6' - cotton/lotex

MISCELLANEOUS FLAT GOODS HAIR CLOTHS - 100%cotton - 50% polyester/N% cotton DIAPERS

- 10096 cotfon LAUNDRY BAGS 3OWx45"- 65% polyester/35%cotton

DUST CLOTHS f B"x24" - 100%cotton - blend

LINEN SUPPLY FLATWORK/lable linen NAPKINS. CORDED 18"x18" - 100%cotton

SWEEP TOOL COVERS M"x36" -- 100%cotton

NAPKINS. MOMlE 18"x18" - 100%cotton 20nx20" - 100%cotton 22"x22" - 100%cotton - 50%polyester/50%cotton

LINEN SUPPLY FLATWORK/Aprons and miscellaneous flat goods APRONS BAR/WAIST - 100%cotton - 65% poIyester/35%cotton - 50% polyesier/50% cotton

Law

Hlgh

32 33 33

31 30 30

43 36 38

NAPKINS, DAMASK ZO"x20" - 100%cotton - 100%polyester

High

Welght In pounds of 100 clean, dly p l o w s

WelgM In pounds of 100 clean, d y pieces Weighted

Range of weight Law

Hlgh BEDSPREADS. SINGLE - 100%cotton

TABLECLOTHS. MOMlE 45"x45" - 100%cotton 54"x54" - 100%cotton 63"x6Jn - 100%cotton 72"x72" - 100%cotton 8Ivx81" - 100%cotton 9O"x9OV - 100%cotton

BLANKETS, SINGLE - 100%cotfon

UNEN SUPPLY FIATWORK/TOW~IS HOHIErn BAN~CLUB/DOCTOR/OFFICE 14"x21" - 100%cotton 14"x25" 100%cotton

TABLECLOTHS, DAMASK 54"x54" - 100%cotton - 100%polyester 63"x63" - 100%polyester 72"x72" - 100%cotton - 100%polyester 81"x81" - 100%polyesfer BANQUET CLOTHS, MOMlE 6feet - 100%cotton 8 feet - 100%cotton 10 feet - 100%cotton

Low

- 54" WIDTH

-

BARBER/BEAUTY W x 2 7 " - 100%cotton 107 136 167

106 149

110 180 191

DISH TOWELS 36"x24" - 100%cotton 3Vx30n 100%cotton

-

GLASS TOWELS LINEN SUPPLY FlA1WORK/Beddlng SHEOS. SINGLE 63"~100"- 50% polyester/50%cotton 66"xI 15" - 65% polyester/35%cotton - 50% polyester/50%cotton

15"x27"

-

100%cotton

91 116 134

63 115 130

118 125 134

HAND TOWELS 46x30" - 100%cotton 16"x32" - 100%cotton

50% polyester/50%cotton

118 118

105 115

124 118

KITCHEN TOWELS 45"x26" - 100%cotton - 50%polyesfer/50% cotton

SHEEIS. DOUBLE 8f"XfOO" - 65% polyester/35%cotton - 50%polyester/50%cotton 81 "X104" - 50% poh/ester/50% cotton 81"~108"- 65% polyester/35%cotton

134 142 144 127

105 131 125 120

148 143 150 153

SHEETS, QUEEN 90"x108" - 50% polyester/X% cotton

170

158

173

PlllOWCASES 42"x33" - 100%cotton - 65% polyester/35%cotton - 50%~olyester/50%cotton 42"x36" - 50% polyester/50%cotton

26 23 24 25

23 19 21 24

30 25

SHEEIS. TWIN 72"x40OU

-

65%polyester/3595 conon

BAR MOPSISWIPES. RIBBED 20Mx17" - 100%cotton CONTINUOUS TOWELS 4050 yds. - 100%cotton - 80%polyester/20% cotton - 71%polyester/ZQ%cotton 50% polyester/50% cotton

-

TERRY

33 27

BATH MATS 18"x24" - 100%cotton 20"x30" - 100%cotton

Hlah

Weight In pounds of I00 clean, dry pieces Welghted average

WelgM In pounds of I00 clean, dry pieces

Range of weight repor)ed

Low

Weighted average

Hlah

-

MASSAGE/HAND 15"x25" - 100%cotton 16"x26" - 100%cotton

LINEN SUPPLY GARMENTS CAPS, CHEF

GOWNS, ARTIST'S Not-fitted,Long Sleeve - 65% polyester/35% cotton Seml-tltted, Long Sleeve - 65% polyester/35%cotton Seml-fltted, 314 Sleeve - 65% polyester/35%cotton

- 100%cotton 65% polyester/35%cotton

COATS. SHORT Chef. Long Sleeve - 65% polyester/35% cotton Chef, Short Sleeve - 65% polyester/35% cotton Counler/Wolter,Long Sleeve - 65% polyester/35%cotton Doctor (Slde Button), Long Sleeve - 65% polyester/35%cotton Doctor (Side Button), Short Sleeve - 65% polyester/35%cotton Jackets, Bartender, Long Sleeve - 65% polyester/35%cotton

Hlgh

DRESSES Belted, Short Sleeve - 65% polyester/35% cotton Rlncess. long Sleeve - 65% polyester/35%cotton Rlncess, Short Sleeve - 65% polyester/35%cotton

WASHCLOTHS, FACE 12"x12" - 100%cotton

COATS. LONG Frocks, Long Sleeve - 65% polyester/35% cotton Frocks, 314 Sleeve - 65% polyester/35% cotton Lugger, Meat/ Butcher- 50% polyester/50% cotton Shop Coat - 65% polyester/35%cotton Wraparound. Long Sleeve - 65% polyester/35%cotton Wraparound, 314 Sleeve - 65% polyester/35%cotton

Low

Jackels, Bus Boy, long Sleeve - 65% polyester/35%cotton Jackets, Lapel, Long Sleeve - 65% polyester/35% cotton Vests, No Sleeve - 65% pobpster/35% cotton

BATH TOWELS 20"x4OU - 100%cott on 100%cotton 20"xM" 22"xM" - 100%cotton

-

Range of weight reported

123

100

133

143

120

150

124

110

126

135

107

156

74

74

81

87

75

105

94

80

105

87

70

105

SHIRTS Kltchen. Short Sleeve - 65% polyester/35% cottohn PANTS SUITS Tops. Short Sleeve - 65% polyester/35% coilon Slacks - 65% polyester/35% cotton

58 89

40 75

75 100

PANTS/TROUSERS Chefs - 65% polvester/35% cotton Cook's - 65%polyester/35% cotton

101 102

78 79

105 108

I

98

63

104

52

50

84

61

58

63

91

73

loo

5

INDUSTRlAL FIAT GOODS SHOP TOWELS 1B"xiB" - 100%cotton - blend 18"x30" - 100%cotton

.-

WelgM In pounds of 100 clean, dry pleces Welghted average

Range of w l g h t repow Low

Weighted average

Hlah

82 66 80

80

88 81 80

SEAT COVERS bO"x72" - 50% polyester/50%cotton

153

140

180

79

60

BEDDING BEDSPREADS, SINGLE 7 0 ~ x 9 0-~ 100%cotton 72"x99" - 100%cotton

BLANKET, BABY 3OWx40"- 100%cotton Jb"x40" - 100%cotton

INDUSTRIALGARMENTS WORK APPAREL COVERALLS Heayweighl - 65%polyester/35% cotton Lightweight - 65% polyester/35%cotton JACKETS Eisenhower - 65% polyester/35%cotton Hlp Length - 65% polyester/35%cotton Wolst length - 65% polyester/35%cotton JUMPSUlT/SPEEDSUIT Long Sleeve - 65% polyesfer/35% cotton Short Sleeve - 65% polyesfer/35%cotton PANTS/TROUSERS - 65% polyester/35%cotton SHIRTS Long Sleeve - 65% polyester/35%cotton Short Sleeve - 65% polyester/35%cotton

EXECUTIVL APPAREL SHIRTS Long Sleeve - 65% polyester/35%cotfon Short Sleeve - 65% polyester/35%cotton

BLANKET. BATH/ETHER/SHEET 70~x90"- 100%cotton BLANKET, THERMAL bb"x90" - 100%cotton INCONTINENCE PAD 2dnx36" - 100%cotton 34"x3bU - 100%cotton MATTRESS PAD 39"x76" - 100%cotton PILLOWCASES 42"x3JV - 65% polyester/35%cotton - 5096 polyester/50%cotton 42"x3bM- 65%polyester/35%cotton - 50% polyester/50%cotton SHEETS, DRAW S''x84 " - 65% polyester/35%cotton SHEETS, SINGLE 66"x404"- 50%polyester/50%cotton bbnx145" - 65% polyester/35%cotlon - 5D% polyester/50%cotfon

TERRY TOWELS SlACKS/PANTS

- 65% polyester/35%cotton

-

100% polyester

Range of weight repocted

Low

HEALTHCARE FLATWORK

FENDER COVERS 3b"xbO" - 100%cotton 50% polyester/50%cotton 100%polyester

-

Weight In pounds of 100 clean, dry pleces

BATH MATS 20"x3OW - 100%cotton BATH TOWEL 20nx40" - 100% cotton

-

Hlgh

WelgM In pounds of 100 clean. dw DI-s Welghbd average

Range of welgM repow

Low

Hlah

--

APPENDIX 2: CAPACITIES OF CYLINDRICAL TANKS

FACE TOWEL

-

Wx26"

100% cotton

WASHCLOlH 12"x12" - 100% cotton

SURGICAL/OPERATING ROOM FLATWORK WRAPPERS 24"x24" - 100%cotton Wx36" 1M3% cotton 54"x54" - 1CQ%cotton

-

HEALTHCARE GARMENTS

ADUM PATIENT APPAREL GOWNS

65% polyester/35% cotton 50% polyester/50% cotton 50% ~olyester/50%cotton 100%cotton 65% polyester/35% cotton 50% polyester/50% cotton 100%cotton 50% polyesler/50% cotton

Bathrobe Isolation O.R.

INFANT PATIENT APPAREL Shirt

-

100% cotton

SURGlCAL/OPERATlNG ROOM GARMENTS PANTS SUIT, TWOPIECE - 50% polyester/50%cotton SCRUB DRESS - 100%cotton SCRUB SUIT

-

50%polyester/SO% cotton

SURGEON/NURSE GOWN 100%cotton

-

VerHcal cylinders 20 53

90

20

52 55

25 57 138

Tank dlameier In feel

1 1.5 2 2.5 3 3.5 4 4.5 5

5.5 6 6.5 7 7.5 8 8.5 9 10 11 12

U.S. gallons

p e r loot of depth 5.87 13.22 23.50 36.72 52.88 71.97 94.00 119.0 146.9 177.7 21 1.5 248.2 287.9 330.5 3 76.0 424.5 475.9 587.5 710.9 846.0

Tank dlarneter In f e d

U.S. gallons per foot d depth

13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

Abstracted from The Permutit Water and Waste Treatment Data Book

992 9 1.152 1.322 7.504 1.698 1.934 2.121 2.350 2.591 2.844 3.108 3.384 3.672 3.972 4.283 4.606 4.981 5.288 5.M6 6.016

APPENDIX 3: CONVERSION FACTORS TEMPERATURE CONVERSION TABLE This table converts temperatures from degrees Celsius to degrees Fahrenheit or from degrees Fahrenheit to degrees Celsius. T h e number to be converted is located in Column A. To convert from OF to OC, read to the left of Column A. 'I'o convert from "C to O F , read to the right of Column A. Degrees Celsius are identical to degrees Centigrade; however, the word Celsius is preferred. Values not included in the table can be calculated by one of the following two equations:

Temperature conversion table "C

-1 7.8 -15 -12.2 - 9.4 - 6.7 - 3.9 - 1.1 1.7 4.4 7.2 10 12.8 15.6 18.3 21.1 23.9 26.7 29.4 32.2



0 5 10 15 20 25

% . 35 40 45 50 55 60 65 70 75 80

85 Q3

A OF

32 aI

50 59 68 77 86 95 104 113 122 131 Ido 149 158 167

176 185 194

OC

35 37.8 40.6 43.3 46.1 48.9 51.7 54.4 57.2 60 62.8 65 6 68 3 71 1 73.9 76 7 79.4 82 2 85