Appendix A

Problems With Fiber Reactive Dyeings Not Repeating - .A Look at Five Typical Cases

By: Brent Smith, Keith Beck, and Tod Uadderra College of Textiles, NCSU Raleigh, NC

Reprinted with permission f” American Dyestuff Reuorter (September 1990) Problems With Fiber Reactive Dyeings Not Repeating- A Look At Five Typical Cases

-! By Brent Smith, Keith Beck, Tod Madderra School of Textiles, N.C.S.U. Raleigh, NC

Introduction igure 1-Data acquisition system. demonstrated by our real-time data While it’s a fact that the fiber reac- acquisition system. tive dyeing of cellulosic materials is of great commercial importance, it is also one of the most difficult batch Case I: A “Normal” Dyeing with prdcesses to control. As part of a Triazines Consortium for Research in Apparel, Dyeings known to have good pro- .. Fiber and Textile Manufacturing duction history generally use dye (CRAFTM), the authors have de- combinations with similar exhaus- : I veloped a system for acquiring real- tion and substantivity characteris- time on-line data from batch dyeings. tics. A typical case is shown in Figure Actual production dyeing problems 2 for a combination of two mono- can now be diagnosed in our own chloro triazine dyes, Orange 13 and laboratory using data from this data Violet 1. The kinetics of exhaustion acquisition system. This information as well as the substantivity of the is a great asset to both laboratory dyes clearly produce similar exhaust ’. I and production dyers in establishing curves up to the time of alkali addi- dye recipes and procedures which, tion (25 minutes). Addition of alkali, due to their inherent design, repeat which in this case produces essen- consistently and resist shade varia- tially no further exhaustion of the tions. le dye procedures and recipes. bath, initiates the reaction phase of The data acquisition system is de- To control fiber reactive dyes, onc the dyeing. The overall reaction rate scribed in more detail elsewhere’.*. lust consider many important fac is controlled by several factors: con- Data from this system include infor- )rs, such as diffusion, reactivity anc centration of dye present, concentra- mation about dye concentration in Jbstantivity. In addition, there arc tion of nucleophile (i.e., cellulose or the dye bath at any time, conductiv- nportant differences between type! hydroxyl anions), and reaction rate ity, pH and temperature. In addition ‘hich must be taken in account constant. The fixation efficiency de- to diagnosis of dyeing problems, hese differences are graphicall) pends on the relative reaction rate of . -. . these data can be used for other pur- .. poses such as modelling and study- .. igure 2-Dye exhaustion vs. time-Violet 1 and Orange 13. .. ing dyeing processes, and real time process control. The system consists of sensors to detect pH. conductivity, temperature, dye and chemical concentrations in the dyebath on a real time basis; sig- nal- conditioners; micro and mini computers; displays and peripherals, as shown in the block diagram in Figure 1. We have used this appa- .. ratus to examine dyeing recipes and procedures with exceptional produc- tion history (good and bad). Data from such dyeings show exactly why some dyeings “went wrong,“ and also indicate how to improve the per- formance of these shades in terms of I ~~~ The dye with cellulose compared to Case II: Triazine Dyes of Differe tive efficiency of fixation of the two water, which in turn depends on the Substantivity dyes will depend on their relative re relative amounts of dye in the fiber Figure 3 shows another combin action rates which in turn depend on and in the dyebath respectively. Note tion shade of two monochloro tri their relative concentrations in the that, at the time of alkali addition, ex- zine dyes, Yellow 135 and Blue 5. I fiber. Even with all other factors (e.g., haustion has essentially reached a in case I, exhaustion of each dye hi reactivity of the dyes) being equal, steady state, thus the timing of the reached a relatively steady state pril the fraction of blue dye in the fiber is alkali addition is not critical. Also, to alkali addition. But in this cas about half as great, giving much the exhaustion is moderate to high the yellow component is nearly 80 lower fixation efficiency and more for fiber reactive dyes-about 60% at exhausted at the time of alkali adc hydrolysis. Thus, the “hot patch” the time of alkali addition. Under tion, compared to just over 40% fl taken before washing will contain these conditions, reaction of the dye the blue. much more unfixed hydrolyzed blue with the fiber occurs reproducibly This has important practical imp dye, which will wash out and the and efficiently. cations to the dyer because the re1 shade will wash down to a more yel- low cast. The dyer will be faced with a hot patch decision requiring con- siderable judgment as to how much the shade will change on washing. Case 111: Alkali Added Too Soon Figure 4 shows a combination of !wo dichloro triazine dyes, Yellow 7 and Blue 4. Although alkali was added after the same time (25 min- Jtes) as in the two previous cases, :he data clearly indicate that, in this :ase, dye is still exhausting. There- ‘ore, the timing of the alkali add has f great effect upon the ultimate shade. If alkali is added slightly ear- ier than specified, more dye will re- nain in the bath and thus relatively ess of the dye will be fixed. Control If the alkali add must be almost Introducing.. . ?xact,since any deviation in the tim- ng of alkali addition or even at the ime it takes to circulate the alkali hroughout the dyeing machine Stater by Washex :ould well produce shade variation. lther factors (e.g., fabric prepara- ion, temperaturehate of rise, salt The Features The Results :oncentration) might well advance Superior STATIC EXTRACTION Improved productivity-no straight- )r retard dye exhaustion slightly, and CAPABILITY is a reality with a ening is required; and this design hereby significantly affect shade re- unique and revolutionary design feature costs less than specialized jeatability. feature found only in Washex static dye machines. In cases I and II exhaust to a steady Textile Dyein&xtractors. tate existed prior to alkali addition. :or those processes, ultimate dye The Benefits lxhaustion depends primarily on the call toll-free outside Texas: inal conditions in the exhaust Ideal for dyeing pantyhose, knit (800) suits, lingerie, and panties. Recent 433-0933 ihase, e.g.. temperature, salt con- tests confirm that STATEX inside Texas: entration and liquor ratio. Mo- dyeing/extractors reduce picks and (817)855-3990 nentary fluctuations do not substan- tangles more than 50%. ially affect the final exhaustion. But, i this case, dye continues to ex- laust after the addition of alkali, giv- -- - -.-e*-zz ig simultaneous exhaustion and re- WASHEXe9 ction. The dyeing results then D.,..- -. ,.-~,-~~~”,.- &.,-A&:q lecome highly path dependent and IY ny fluctuation in the factors previ- Washex Machinery Company usly mentioned is likely to result in Division White Consolidated Industries, Inc. poor shade repeat or unlevel dye- 5000 Central Freeway ig. This is a higher risk situation and Wichita Falls, Texru 76306 ?quires more careful control to P132a chieve good shade repeats. Circle 24 on Reader Service Card 40 American Dyestuff Reporter 0 September 1990 a .-- Gigure &Dye exhaustion vs. time-Yellow 135 and Blue 5. Figure &-Dye exhaustion vs. time-Yellow 7 and Blue 4.

0

YOllOW 135 - Yellow 7 - BlrU.5 --- Blue4 --- 0 a-- - - - __ I

0 10 20 30 40 50 60 70

Tlm (Minuter)

:igure -ye exhaustion vs. time-Blue 3R and Blue 21 Figure &Dye exhaustion vs. time-Blue 19 and Red 180.

,

0 .-0 T- ElW33R - Blue19 --- Elm21 --- Red180 - I m0.

0 10 20 30 40 50 60 70

TIM (Mlnuter)

:ase IV: Vinyl Sulfones of Different leactivlty Figure 5 shows the performance of combination of two sulfatoethyl ulfone dyes, Remazol Blue 3R (no .I. Number) and Blue 21. (Note- ue to pH sensitivity of the dyes in lis reme, a scale factor adjustment was made at the time of addition of ilkali.) These dyes have very compat- ble exhaustion prior to alkali addi- ion and reach a fairly steady state. 3ut, in contrast to the triazine dyes fescribed in the preceding, these fyes commence exhaustion again

42 I

I ently unstable shade repeats can b identified by examination of dyebat The Textile data. Dye recipes and procedure which are high risk can be identifie1 Industry’s in advance using real time dyebatl data acquisition. Air In these studies the authors suc don similar to cases Ill and IV. Thi: cessfully identified several specifit Pollution y!, .-_-muires careful control of many fac situations leading to higher risk o tors, e.g.. temperature and alkali ad poor shade repeats in fiber reactivc Solution dition, to achieve good shade re - _------. -- dyeing as demonstrated by thesc peats and level dyeings. - cases. A few of the most prominen problems included (a) selection o 1- Conclusions dyes of different affinity or reactivit! Fiber reactive dye formulation: and (b) addition of alkali toc and procedures vary greatly in theii soon. 0 0 0 performance. Even if dyers had es sentially perfect control over theii processes, shade variations would leferences 1 ) Madderra. Tod. Development of a Rea still result from uncontrollable fac. Time Data Acquisition System for Batct tors such as fiber maturity, ambienl Dyeing, Master’s Thesis, NCSU College conditions, water quality, dye and of Textiles, 1990. chemical variances. Therefore, it is 2) Beck. Keith, Madderra. Tod and Smith, important to devise dyeing protocols Brent. Real-Time Data Acquisition in Batch Dyeing, in press, Proceedings oi which ale highly resistant to varia- the 1990 AATCC National Technical Photo: Third precipitator on the far tions. Situations which lead to inher- Conference and Exhibition. right is shut off to show the difference in smoke emission compared to the other two operating units.

Selecting Dyes.. . 3) Houser, Nelson. Direct Dyes. Clemson POLTTUBE by :Continued from page 751 University, Continuing Education Sym- BELTRAN posium on ”Dyeing Fundamentals.” Wet Electrostatic September, 1989. Precipitator ~umerthe diversity of product mix 1) “Modest Increases in Production and Earnings Offset by Imports,” Textile lor styling and differentiation.000 Chemists and Colorist. Research Trian- Operates wet or dry gle Park, February 199ONol. 22, No. 2. High Collection efficiency at p. 2. high veloclty ‘I) J. Gordon Cook, Handbook of Textile “2.4 Billion and Growing,” ATI, April Low energy use =ibers2. Man-made Fibers, p. XXVIII. 1988, p. 67. Rigid electrode 2) C. H. Giles, The Theory of Coloration i) Park, J. A Practical Introduction to Yarn Economical operation - )f Textiles, p. 41. Dyeing, West Yorkshire, The Society of low pressure drop Dyers and Colourists, 1981. Fabricated from corrosion leferences i) Trotman, E.R. Dyeing and Chemical resistant materials such as: 1) Cook, J. Gordon. Handbook of Textile Technology of Textile Fibers. Sixth Edi- Fiberglass Reinforced fibers, 1. Natural Fibers, 2. Man-made tion. New York, John Wiley and Sons. Plastic Fibers, Durham, Merrow, 1984. 1984. Upgrade scrubber systems AATCC, Dyeing Primer. Research (7) COLOR INDEX. Third Edition. York- increasing efficiency and Triangle Park, AATCC, 1981. shire, The Society of Dyers and Colou- reducing horsepower. 2) Giles, C.H. “Dye-Fibre Bonds and Their rists. 1971. Investigation.” The Theory of Coloration (8) Weigle. Palmy. Ancient Dyes for Mod- of Textiles, West Yorkshire, The Dyers ern Weavers. New York. Watson-Gup- Eliminates Smoke, Company Publications Trust, 1975. till, 1974. Odor, Particulate and Fumes from Wet Processing Operations. News Beltran with over 500 [Continued from page 141 installations worldwide, is the textile industry’s most experienced supplier of air Acquisition Agreement pollution control equipment. Crommn & Knowles Corp. Stam- did announce that the acquisition d, CT. recently announced it has would be made for cash and is ex- ned a definitive agreement to ac- pected to be completed in the third BELTRAN~~ uire the business and certain asse.ts quarter of 1990. BELTRAN ASSOCIATES INC. f Atlantic Industries, Inc., a Nutley, Atlantic Industries, Inc., is an indi- 1 133 East 35 Street, ased producer of dyes for the rect, wholly-owned subsidiary of Brooklyn, New York 11 21 0 e industry. Great American Management and In- 718-338-331 1 hough details of the proposed vestment, Inc. FAX: 71 8-253-9028 action were not revealed, C&K [Continued on page 1061 Circle 65 on Reader Service Card mber 1990 0 American Dyestuff Reporter 95 Troubleshooting In Dyeing-Part I: General

By Dr. Brent Smith, NC State University, Dept. of Textile Chemistry, Raleigh, NC Second In a series of ten articles by Dr. Brent Smith on the theme, ‘Troubleshooting In Dyeing.”

:Igure 1 Troubleshooting of dyeing prob lems is a difficult task because s( Nernst Isotherm : Partitioning of Dye between many variables are involved an( ‘Substrate and Liquor by Solubility Effects n DYQ because observers are very sensitivc rc to minor variations in dye application 0

This article, Part I, reviews several im U portant factors that apply to dyein{ in general, including: L 01 t Basic dye theory; n .d Color standards and shade guides LL Color judgments; C Raw material and substrate variation 4 Automat ion; c 0 Dyestuff quality controi; and, ...I Standard test methods. 4J 0 Parts I1 and Ill will deal with L 4J ipecifics of batch dyeing and of con. S inuous dyeing, respectively. 01 0 S ~~~ ~ 0 Iyeing - The Basics U Before getting into specific details Dye Concentration in Dye Liquor C Os] if problem solving in dyeing, it may le helpful to briefly mention some ‘igure 2 lasic concepts of dye theory. Twa nportant and fundamentally dif. ?rent branches of dye theoryshould e understood, which are: - 0 Kinetics (Mechanisms, Rates); ce 0 Thermodynamics (Equilibria, E! Isotherms). nA To be a successful dyer requires nowledge and understanding of ow these elements are affected by ianaging various parameters, as ell as the ability to apply these prin- ples then to the practice of dyeing. 0 nere are several basic dyeing -I=I // ,echanisms, as shown in Table 1. K-CSf 1 CD, 3 Some of these mechanisms are us- 01C CDfl - 1 by exhaust dyers, 1.e. dlstrlbu- 5 I/ 1 + K*CD, 1 in, affirlity, and (less often) entrap- 0 L I ent. Others, especially entrapment 0 id binding, are often used by con- U iuous dyers. The exhaust dyer at- Concentration in Dye Liquor COS] mpts to produce an even, repro- lcible shade by diffusion, migra- ion, and subsequent fixation of dye 2 represented by the three dyeing mechanisms represent varying in a substrate through an approach ,therms shown in Figures 1, 2 physical situations which’exist witt to equilibrium conditions. Three d 3. particular fiberldyestuff combina These isotherms and dyeing tions, as shown in Table II. They arc

March 1987 C Amedcan Dyestuff Reporter 77 I

troiyte, dyeing auxiliaries. an rigure 3 temperature. Each isotherm e Freundlich Isotherm : Dye Interacts Weakly with presses a relationship betwee equilibrium concentrations of dye i Substrata - - Hydrogan Bonding or Von der Wools the fiber [Of],dye in the dye liquc n (e' [D,] also, dyesites in the fiber [S, 0 and constants (N,K) which ar U characteristic of the system. Thes isotherms represent specifi L equilibrium conditions and are if fluenced by many specific factors fc different dye classes. Control 0 these factors is essential for consis tent dyeing. These will be reviewet on a class-by-class basis in Part 11 COS IN= In commerce, the equilibrium K ED+ which is represented by the isotherm is never fully attained. Thus, anothe critical factor for the exhaust dyer i: 1 the kinetics or rate of dyeing, a! 0 U shown in Figure 4. This rate must bt Concentrotion in Dye Liquor CDs3 :arefully tailored to the isotherm specifics of the equipment, dye, anc substrate. Exhaust curves expres: igure 4 :he rate df exhaust in terms of thc Uyaing kxhaust Curve iltimate (equilibrium) percent of dyc Based on Amount of Dye in the Fiber Nhich will exhaust (E-) as well a! * he time (t*) required to obtain hall q 1 f that amount of exhaustion. Ex- 1 I aust curves are non-equilibrium ata based on percent exhaust imounts, not concentrations) of dye. :ontrol of many critical factors which ffeCt tm is essential for good shade 2peats and level dyeings. The shape f these exhaust curves will depend n dyeing conditions, variations in mperature, electrolyte, pH, etc. hese considerations will be discuss- d in depth in Part 11. The continuous dyer, on the other and, depends on uniform wetting )Ilowed by fixation or binding steps %e one under non-equilibrium condi- Tima ons. To produce even dyeings in lis situation, adyer gives careful at- mtion to mechanical details as well Idor, color standards (physical or particular color. Color standards are as chemical reactivity, penetration of imerical) are universally used by necessary in the development of new dye, etc. Critical parameters for the ers for judgment of dye lots. Of shades and coordination of different continuous dyer will be discussed in urse. the judgment is no better component parts. Part 111 of this article, "Trouble- an the sample taken from the dye A shade guide, on the other hand, shooting in Continuous Dyeing." . It is also no better than the stan- is a secondary standard of a par. Control of shade and evenness of rd. Having a good standard as well ticular dye recipe on a specific dyeing requires attention to different as a good sample from the lot is substrate in a certain state (for exam. details,-depending on whether the ap- critical for both instrumental and pie, finished or not finished). The use plication is exhaust (batch) 'or visual shade judgments. What con- of shade guides greatly facilitates continuous. stitutes a "good" standard depends both instrumental and human colol on many factors. judgments by avoiding certain prob- Color standards and shade guides At this point, it is important to lems. One such problem is possible One critical area in dyeing quality define the distinction between a "col- metamerism between the color Stan, :ontrol is the selection, establish- or standard" and a "shade guide." dard and production lot sample, nent, storage, and use of color stan- The color standard is a primary stan- which can result from differences in lards. Since the human mind has dard which could be any physical ob- dye recipes. By using shade guides eiatively poor ability to "remember" iect or numerical specification for a Iin s t ead of color standards).

Amerlcan Dyestuff Reporter 0 March 1987 I

metamerism and the effects 01 Table 1: Mechanisms of Dyeing lighting variations are minimized 1. Simple distribution of dye between the substrate and dye liquor (non-ionic) Problems arising from observe! metamerism are also reduced. Fur 2. Specific affinity of dye for fiber by hydrogen bonding, Van der Waals forces, Or ionic thermore, potential problems arisin5 interaction which may occur at specific sites, by electrical effects, or formation Of bonds. from appearance differences be. tween the color standard and lot Sam. 3. Mechanical entrapment of dye within fiber. pie such as nap or other surface finish, luster, gloss, and haze are 4. Binders which hold pigments in place on the fiber surface. reduced. The use of shade guides also improves performance of in. Table II: Physical Mechanisms, Dyeing Behavior, and Isotherms strumental color judgments. Dyeing mechanism Fibeddyestuff example Observed behavior isotherm An ideal shade guide is a full, Simple distribution disperselsynthetic Nernst scale, no-add production dyeing ofa Specific affinity Acidlwool particular recipe on a specific Acidlnylon Langmuir substrate. Less desirable situations Basiclacrylic include (from "better" to "worse"): Directlcellulose Freundlich Lab dyeings (same recipelsub, Entrapment Vat' st rat e); Sulfur' None' Sample production lot (short run of Naphtol' partial load); Binding Pigment None Rehandled production lot, "topped 'Exhaust dyers apply certain types of dyes in a two-step procedure, in which the ex- up," or lot with dye add: haust phase (described by an isotherm) is followed by a reactive phase not described Different substrate andlor recipe; by any isothem. and, Non-teRtile material. In addition to the preceding, the rable Ill: AATCC Test Methods Relating to Preparation' nannerof drying and conditioning is rest Property :ritical for both the shade guide and lumber ot sample. Drying temperatures, !O and 20A ...... Fiber Identification imes, tensions, and surface contact 17 ...... Extractable Materials :an cause considerable shade varia- '8 ...... Ash Content ion between samples. Tensions and '9 ...... Absorbency...... :ontact (such as with steam heated 144...... Alkalinity of Substrate lrying cans) may cause a change in i1 .pH of Substrate 12 ...... Fluidity he surface appearance of samples 17,27,43 ...... Wetting ,ecause of surface fusing, thermal ~9...... ,...... ,...... Mercerization wiking, shrinking, or stretching of 38 ...... Alkali in Bleach Baths he substrate. The use of gas-heated 102 ...... Peroxide in Bleach Baths 103...... Enzyme Activity lrier vs. electrically heated vs. hot 149 ...... Chelates :ans may give different shade 110...... Whiteness :hanges. Finishing recipes should be con- istent between shade guide and lot have no documented standard' pro. be studied carefully by anyone who ,ample, especially with respect to cedure for making a visual color judg- makes use of CADltextile color :atalysts, which may cause shade mpnt. Many companies have stan- systems.5 Since color vision is not :hanges in cellulosic and other dyes, dard lighting surroundings. Some instantaneous, and because of suc- ind with respect to softeners which even have standard presentation cessive contrast effects, the time of nay be fluorescent or may contain methods and color testing for the observation as well as the luorescent brighteners. observers. Few, if any, have specific "resting" time between successive :oror Judgments instructions forobservers with regard observations is important. Also, long Having obtained an adequate to other factors involved. Important term fatigue plans an important role hade guide and lot sample, one considerations for visual judgments in color judgment if an observer lust then make a comparison of the Df small color differences are works for several hours. YO for some purpose, such as ac- described in the literature.3.' These There are many factors which must eptingor rejecting the lot. This can recommended practices should be be carefully controlled in order to B done instrumentally or visually. mderstood by each person who make color judgments which are 9e practical details of how to make makes critical commercial color reproducible and correlate with the lstrumental color judgments are udgments. more important factors in perceived !ported in the 1iterature.lJ Usually, A different set of considerations color: specially in cases of problems or, applies, however, when comparing -Illumination; sputes, visual color judgments will {ideo displays to textile materials, for -Sample preparation and presenta- B the deciding factor. It is amazing 2xample when using computer aided tion; ial many processors who rely heavi- jesign systems. An excellent review -Surroundings; on visual color judgments usually ,f this subject is available and should -Observer; and,

19 .*_.-a. .no- - dmarlc~nDvestuff Reoorter / - Intangibles. Table IV: Defects and Latent Defects Which Come from Preparation’ Consistent color judgments arc not difficult to achieve. However, i Defect AATCC test method is surprising how often the followin! Residual waxes and oils #97 Extractable Materials iundamental ground rules art Silicate deposits #78 Ash Content JVerlOOked, leading to problems. Uneven absorbency #79 Absorbency Residual alkalinity #81 pH and #144 Alkalinity Illumination is usually well con Fiber damage #82 Fluidity trolled in dyeing and laboratory en Poor bleach base #110 Whiteness and vironments, but not in other en #78 Ash Content ,vironments, such as cut-and-seH Resist (oxycellulose) Several Methods6 Poor mercerization .#89 Barium Number areas or meetinglconference rooms Residual peroxide Spot Test? Normal color matching is usuall) done under daylight, incandescent These tests have been ad. Table V: Dyeing Defects and Water cool-white fluorescent, andloi Contamination Ultralume@lighting. Techniques ministered to hundreds of students in academic and extension courses equipment, and effects of varying Inconsistent shade: lighting are well known. Lighting at NCSU and the differences which Chorine should be controlled in spectral are commonly detected between -Iron and copper [sensitive dyes] energy content, level or intensity, and “normal” observers is surprisingly -Calcium and magnesium [poor wash. great. Furthermore, observers usually ing off] diffusion. Blotchy or streaky dyeings: Shade guides and color standards find it hard to believe that everyone -Alkalinity or acidity should be handled and stored care. does not see color the same. Thus, it -Residual alum from city treatment fully. seems only reasonable that every systems Exposure to light, burned-gas person who is associated with com- Filtering, spots, resist: mercial shade developments should -Sediment fumes, and other atmospheric con- -Organics taminants can cause changes in col- be tested on a frequent basis. This is -Metal hydroxides, fatty acid complexes 3r. Also, residual chemicals in paper I and plastic holders cause changes in Table VI: Thin-Layer Chromatography5 color of a stored sample, if tpe sam- Dye Developer Solvent Adsorbent ple comes in contact with them. Nor- class system proportions mal use of shade guides causes them Acid n-ButanollAcetonelWaterlAmmonia 5:5:1:2 Silica Gel G ’0become stretched, dirty and abrad- Methyl Ethyl KetonelAcetoneMlater 2-4:1:1 Silica Gel G i, causing a change in appearance n-ButanollEthanollWater 1 -2:1:1 Alumina G and color. Therefore, shade guides 3asic n-ButanollEthanollWaterlAceticAcid 9:1:1:0.1 Silica Gel G must be monitored and replaced n-ButanollAcetic Acidwater 2: 1:5 Kieselguhr when necessary. The frequency of Pyridinemater 1:2 Silica Gel G EthanollWater 5:2 or neutral replacement will depend on the Alumina amount of use, physical properties of )ired n-ButanollMethanollAmmonialPyridine 4:1:3:2 Silica Gel G the guide, and how carefully the Propanol/25% Ammonia 2:1 Silica Gel guide is handled. Sample and guide PyridinelAmylAlcohol/25% Ammonia 1:1:1 Silica Gel presentation should be consistent in Iisperse ToluenelAcetone 20: 1 Silica Gel orientation, size, viewing distance, iolvent ChloroformlHexanelAcetone 3:l:l Silica Gel conditioning, edge contact and prep- faphthol ChloroformlAcetone 9: 1 Silica Gel MethanollMethyl Ethyl Ketone 5:2 Silica Gel aration. Surroundings should also be 3eactive Butyl AcetatelPyridinelWater Silica Gel controlled carefully. The usual pro- 22:l n-ButanollPyridinelWaterlAmmonia 5:5:3:2 Silica Gel cedure is to use a flat-gray surroun- PropanollEthyl AcetatelWater 6:1:3 Silica Gel ding of about 18% reflectance, cor- detallized ChloroformlEthanoIlMorpholine &1:1 Silica Gel responding to a photographic gray 21) card or a MunsellQ color designation Df N6 to N7. rarely done in commerce, perhaps dividuals, such as: Another critical factor in color because many color professionals -Quality control manager: Who is udgments is the observer. There are are reluctant to take these tests. the customer? iubstantial differences between There are other modifying factors -Plant manager: When is the lot rbservers with “normal” color vision. related to color vision beyond ob- due out? ’hese differences go beyond the server differences. These include -Dyer: What are the chances that lross colorblindness detected by fatigue, impairments, successive and reworking the lot will make it better? These factors can never be complete- ly eliminated from color judgments.

Raw materials and substrates tamerism, which may be detected The two fundamental sources of and quantified by use of the Munsell- product variation are raw materials Farnsworth Hundred Hue Color Dis- (including substrate) and processing. crimination Test” and the Glenn Col- It is not possible to properly optimize or Rule@,respectively. processing conditions and equip

P20 Amerlcan Dyestuff Reporter 0 March 1987 merit while important raw material ( substrate variation is significant. Thl Table VII: Paper Chromatography5 is especially true io dyeing oper, Solvent tions. Control methods for chemic; Dye Developer system proportion specialties, chemical commoditie: class Acid Ethanol or Methanolwater 4: 1 and the substrate itself are presente t-Butanolln-Butanollater 433: in other parts of this series. n.ButanollEthanollWater/Ammonia 2:1:1:1 As to the effect of preparatio Methyl Ethyl KetonelAcetonelWater 24:1:1 upon dyeing, the key is consistenc! Basic MethanollSN Ammonia 8:2 Several standard tests for fabri ButanollAcetic Acidwater 2:1:5 preparation are shown in Table II Pyridinemater 1 :4 1:1:1 Properly administered and inte ButanollEthanol/Water preted, these tests will detec Direct ButanollPyridinelWater 23:3 Benzyl alcohollDMFMlater 322 defects and latent defects which cat 1:1:1 affect dyeing processes. Particula Disperse ChloroformlAcetic Acidwater (on Silicone treated paper) defects and contaminants which frE Pyridinemater 1 :3-5 qently result from improper a Tetrahydrofuranwater or N HC1 80-54 inadequate preparation are alsl (on Acetylated paper) - shown in Table IV, with tests t( Reactive 2% NaaHP04 in 5.1'0 Ammonia detect them. Specific situation ButanolmaterlDMF 11:11:3 relating to these are discussed ii ButanollAcetic Acidwater 2:1:5 other parts of this series. Vat or 10% TetraethylenepentaminelNaiSiOa 10:1 Water quality, as discussed i Sulphur Ethyl AcetatelEthanolkVater 1-23:1 detail in other parts of this series, ha (on acetylated paper) a profound effect on dyeing. Whil Metallized n-Butanollformic Acidwater 5:1:2 specific effects vary, commo (2:1) (on Whatman DE-20 paper) Acid (1:l) Acetic Acidwater 3:2 causes and effects are shown ii Acid (2:l) Tetrahydrofuranlo. 1N HCl 80-54 Table V. (on 80% acetylated paper) The limitations of dyeing-machir zry require one's particular attentior :specially with respect to compatibil ty with substrates. In many cases, rothing can be done to avoid pro 'able VIII: Developing Solvents Polarity: Elutive PoweP )lems arising from the above, bui iometimes these problems can be Solvent Dielectric constanl wercome by improved preparation non-polar m-Hexane 1.9 iven when nothing can be done tc less elutive power) Petroleum ether 2.0 Cyclohexane 2.0 m p rove com pat ib iI it y between Carbon tetrachloride 2.2 ubstrate and equipment, knowledge Benzene 2.3 f the limitations allows for increased Tetrachloroethylene 2.3 luality control checks and proper Toluene 2.4 ost factors, based on anticipated Trichlorethylene 3.4 Diethyl ether 4.3 Igh off quality and seconds levels. Chloroform 4.8 Ethyl acetate 6.0 Automation Phenol 9.8 One trend in modern dyeing prac. Pyridine 12.3 tlce is the use of automated iso-Propanol 18.3 microprocessor controls for dyeing n-Propanol 20.1 Acetone 20.7 equipment. These controls, if proper- Ethanol 24.3 ly maintained and calibrated, can be Methanol 32.6 of great assistance to the dyer. Acetonitrile 37.5 However, there is a tendency for polar Water 78.5 dyers who use automated equipment (more elutive power) to spend less time on the dyehouse floor actually observing the dyeing processes. In fact, automated con- trollerscan lull a supervisor or dyer into the false sense of security that ly unloaded from becks or jets can be Dyes all is well. very revealing in terms of spotting There is, at this time, no com- There is no substitute for the potential problems, which automated prehensive standard AATCC test iyer's personal observation of pro- systems can not detect. This per- method for quality-control testing of :esses running on the floor. , sonal presence and observation of dyes, although procedures are being One look at an unexhausted production processes is important in developed by committee RA98. How- jyebath or unusual color of water batch or continuous dyeing, as well ever, it is necessary for dyers to have jraining from boxes of cloth recent- as in preparation and in finishing. some method of determining whether

24 Amerlcrn Dyestuff Reporter 0 March 1987 r drops of dye mix are spotted on a piece of filter paper. If a problem is later detected, the spotted paper can be eluted to determine qualitatively that the correct dyes were in the mix. Table IX: AATCC Methods Relating to Dyeing' If printing scales were used for rest weighing, the amounts of each dye Number Property weighed can be verified also. Alter- 26 ...... Aging of Sulphur Dyed Clot' native solvents for development 161...... Effects of Chelates in Dyein, of 153...... Instrumental Color Measurement chromatograms are given in Table darious ...... Fastness(25+ Test: VIII. 141...... Basic Dye Compatibilit One of the most important aspects 146 ...... Disperse Dye Filterin1 of testing of dyestuffs is to review all 140 ...... Dye Migratiol test data, good or bad, with the ven- 139 ...... Thermos01 Disperse Dyes on Polyeste 159 ...... Acid Dye Transfe dor. This establishes communica- 156 ...... Basic Dye Transfe tions before problems arise, and also 155 ...... Disperse Dye Transfe makes the vendor aware that the mill is checking. (Vendors also ask the question "Who is the customer?").

Standard test methods There are many standard test methods that pertain to trouble- shooting in dyeing. These are listed in Table IX. The applicability of these tests to various situations in exhaust and continuous dyeing will be or not incoming dyes are inadequatc such as AATCC Test Method 146. described in detail in Parts II and Ill for their needs. The following pro Color value of a dye can be determin- of this article. 0 0 0 cedures are not necessarilyielatedt( ed by transmission measurements the work of committee RA98, but arc after dissolution in an appropriate simply suggestions to the practica solvent. However, this does not ... jyer of some methods which ma! measure certain important properties xove useful. of a dye such as substantivity andlor For each dye in use, it is good prac. fixation properties. Therefore there is References ce to have not only the OSHA Form merit in the practice of evaluation by 1) AATCC Technical Manual, vol. 53, 0 (MSDS)as required by law, but actually dyeing a substrate with the (1986). AATCC, Research Triangle Is0 the manufacturer's technical dye from the drum and with the dye Park,.NC. ata sheet and a physical standard. standard. Results of dyeings may not 2) Smith, Brent, The Practical Side of Us- tandards should be stored in a cool, be directly comparable between dif- ing Color Instrumentation, Textile ark, dry place and should be replac- ferent mills, because different dyers Chemist and Colorist, 17, no. 11. (November, 1985). 3 or updated as recommended by use different procedures and be- 3) Huey, Sam, "Standard Practices for be dye manufacturer. A good quali- cause of even slight variations in Visual Examination of Small Color Dif- control scheme for a dyehouse is water quality. However, using an ac- ferences, Color Technology in the Tex- sample 50 to 100 grams of each tual dyeing has the important advan- tile Industry," AATCC, Research Triangle, NC. ye as received and send to the tage that it is mill-specific. 4) ASTM Test Method D1729, "Standard lboratory for testing. A satisfactory In the event that the dye is used on Method for Evaluation of Color Dif- ,boratory evaluation comprises: blends, be sure to use the blend pro- ferences of Opaque Materials," ASTM, -solubility or dispersion; cedure. For example, a disperse dye 1976 Race St.. Philadelphia, PA (1979). tolor value by either transmission which is normally used on polyester/ 5) Rich, Danny, "Colorimetric Problems in Textile Dyeing Systems Using CRT - dyeing; cotton blends, for disperseldirect Displays," Proceedings of 1985 Inter- -thinlayer, or paper, chromato- one-bath dyeing, should be dyed with national Conference and Exhibition, IraPhx; salt and other direct dye auxiliaries. AATCC, Research Triangle Park, NC -special tests for unique dyes; Care must be taken to have a consis- (Oct. 1985). 5) Feeman, James, "An Introduction to -viscosity, density, and specific tent supply of substrate for use on a Modern Methods of Dye Identifica- jravity for liquids; long term basis for such dyeings. tion-Chromatography and Spec- -retainSample for future reference; Another quick and simple test is trophotometry," Canadian Textile tnd chromatography. Selected develop- Journal, February, 1970. 7) Lange, N.A. ed., "Handbook of -proper documentation. ers for thinlayer chromatographs of Chemistry, Revised 10th Edition." )rums which are suspected of caus- various dye classes are given in Table McGraw Hill, 1967. -- ng problems or which have been VI, and for paper chromatography in B) Weaver, J. William, "Analytical Ipened for a long term should be Table VII. Another application of the Methods for a Textile Laboratory 3rd esampled and retested. paper chromatography technique is Ed.," AATCC, Research Triangle Park. NC (1984). Solubility or dispersion can be in the drug room. When each dye 3) Rucker. James, "Troubleshooting in !asily tested by standard methods recipe is pasted up for use, a few Preparation," in press (ADR).

26 Amerlcrn Dyestuff Raporler 0 March 1987 e Troubleshooting In Dyeing- Part 11: Batch Dyeing

~~ ~ ~

By Dr. Brent Smith, Dept. of Textile Chemistry, NCSU, Raleigh, NC

Abstract ing is poor shade repeats (off shade There is a very widespread impres The first part of this article (Mar. 8; dye in g s). sion that avoiding defects, and espe. ADR) presented some fundamenta In addition to production which cially improving shade repeats, is a aspects of dyeing quality control ir gets out of the dyehouse with an simple matter of discipline. Although general. This part (11) present: unacceptable shade, poor shade supervision, good maintenance, and specific details of controlling batct repeats actually are the underlying proper operation of equipment are jye processes. Critical quality con cause of a substantial portion of important, it is also very important to lrol parapeters are discussed foi physical damages, uneven dyeings, put quality (not cost reduction and tarious dye classes, equipment and foreign deposits. These defects short cuts) as the number one prior- xocesses, and substrates. Also frequently occur when a shade does ity, Management pressure to reduce Yiagnostic tests and repair pro not repeat properly and requires cor- cost or increase production beyond :edures are presented. The final pari rective action such as dye or chemi- reasonable limits (for example, by )f this article will concentrate on cal adds, extra run time, boiling overloading eq u ipmen 1) is frequent- :ontinuous dyeing. down, stripping, redyeing, andlor ly counterproductive. overdyeing . Correctivelre pair pro- ntroduction cedures require extra time and proc- Dye selection Many different classes of dyes are essing; hence, the risk of physical The exhaust dyer has a wide vari- applied to various substrates by damage is greater. Practices such as ety of colorants from which to select batch methods in mill-specific situa. stripping or adds increase the risk of his dye recipe. Many considerations tions using a wide variety of equip uneven dyeing and bath instability. enter into selection of dye class, ment. It would be impossible to Consideration of dyeing econom- subclass, and specific dyestuffs. A review each and every commercially ics and losses associated with dye- typical selection protocol is shown in important combination of circum- ing defects must take into account Table II. Sometimes special situa- stances in depth; therefore, informa. the relative value of the substrate (fre- tions such as unusual blend, sub- tion presented herein is intended quently several dollars per pound), strates, constructions, or production primarily as a guide for troubleshoot- versus the actual labor, overhead, volume arise which require complete ing in a variety of bath dyeing produc- dye, and chemical cost for dyeing review of the entire formulation tion situations. (usually less than $0.50 per pound for protocol. In these cases, it is impor- most shades). Thus, a relatively large tant to make a careful evaluation and Dyeing defects savings in dye cost can be quickly 7ot to treat the situation as "routine." Various types of defects may oc- offset by even a minor increase in To avoid trouble, these situations cur during batch dyeing and par- defect level and the associated nust be identified in advance and ticular combinations of processes, losses such as the loss of expensive iandled properly in terms of equip- equipment, dyes or substrates may substrate. For example, a 10% cost nent, process and dye selection, be more or less susceptible to reduction on a dye cost of $0.25 per quality control requirements, cost specific types of defects. Most pro- pound would be offset by an increase analysis, and expectations for off- duction dyers cite various defects, of only 1% off-quality on a $2.50 quality and re-working. Using a cer- such as those listed in Table I, as substrate. ,ain set of dyes, procedures, cost their major problem areas. However, In addition, that 1% off quality analysis, etc., from habit is sure to :here is no question that the major might be reworked or redyed by a ead, sooner or later, to trouble. iroblem which occurs in. batch dye- costly procedure (causing additional Examples of such situations are economic loss) which has a higher rot difficult to find. One example risk and lower chance to produce ac- vhich frequently occurs is the design tditor's Notes-Third in a series of ceptable product than first-run dye- If difficult-to-dye blends, especially len articles to be prepared by Dr. ings. Thus the dyer's priority must be hree fiber blends, by stylists who do Brent Smith on the general theme, to avoid producing defects. To avoid lot realize the difficulties involved. "Troubleshooting In Wet Proces- defects, the first step must be to pro. 'he dyeing behavior of many binary sing". duce consistent shade repeats.

13 instrumental color analysis of the Figure 1: Fiber Dyeing Chart dyebath or the substrate are also he1pf u I. Exhaust rate compatibility can also be evaluated by private methods such as the Resolin S ACETATE 1. UNlONoNLY Process.@* Failure to select compati- ACRIUN 16 2. UNPREDICTABLE - ble dyes in combination shades will LMwYloNEoNToNE ACRIUN 1656 affect shade repeats. 3. CROSS m. uyK)N. OR Suggestions for quality control of rcREs EITHER nem dyestuffs for a dyehouse are given in Part I of this article. Storage, weighing, and mixing of dyes should be in a cool dry area. Proper ventila- tion and air circulation are important for worker protection and also to pre- vent airborne dye particles from fly- ing or drifting to areas where they might deposit on in-process goods. Certain dyes, especially fiber-reactive powder dyes and many types of li- quid dyes, have a tendency to degrade during storage. All drums of dye (and also chemicals) should be dated when opened. Any drums which are nearing the end of their shelf life, as recommended by the manufacturer, should be retested using standard raw material quality. zont rol procedures. Paste-up of dyes can have a sub- stantial effect on the quality in terms 7f shade repeats as well as specific lefects such as dye spots. Therefore, lye paste-up should adhere careful- y to manufacturers recommenda- ions. General guidelines for drug oom practices given in Table Ill are lot intended to contradict or substi- . --- I ute for specific instructions which I dye manufacturer might provide for ~~ I certain dye. Beyond these specific rocedures and temperatures, how- ver, there are other considerations. )lends is given in Figure 1 (the ester and cotton. An alternativ When dyes are weighed, it is an ad- xiginal source of this widely cir- fabric, with filament acetate yarn o antage to use printing scales for a :ulated table is uncertain). Introduc- the face and lW% cotton yam on th ,emanent record of amounts, and to ng a third fiber can create great dif- back, on the other hand, was relativc lip the corner of a piece of filter iculties for the dyer. ly easy and less costly to dye. japer in the final paste for diagnostic One specific commercial example The two important ideas in thi :hromatography test later, if neces- ,f such a situation involved a poly. example are to design product ,ary. isterlcottonlacetate blend. The idea which have the greatest potential fc If the water is hard, hexaphos if the designer was to make a two- overall profit and when high degref ,houId be added and thoroughly ided fabric with filament acetate of-difficulty products are encour lissolved prior to pasting dye. arn on the face and a spun yarn on tered, to have special procedures fc If chlorine is present in the water, he back. Although the back side of handling them. gram per liter of thiosulfate should hefabric could have been made from In exhaust dyeing, properselectio ie added. Excessive amounts of thio- 00% cotton yarn, the designer of a specific dye combination for ulfate are detrimental. selected 50150 polyesterlcotton yarn shade is critical. Factors such as e) Sequestrants for iron and copper by habit. The resulting three-fiber haust rate (strike), leveling propertie: EDTA, DTPA, NTA) should not be blend (polyesterlcottonlacetate) was and sensitivity to pH and electrolyt ised because many dyes are sen- a dyer's nightmare in dark shades be- must be consistent for all dyes in th itive. If metals such as iron and cop- cause of difficulties in disperse dye formula. AATCC Test Methods 14 ier are a problem, water treatment selection as well as the physical and and 156 for basic dyes, 155 for diz lot chelates) should be employed. chemical damage which occurred to perse dyes, and 159 for acid dyes ar Some paste-up procedures given the acetate while dyeing the poly- helpful.' Exhaust curves prepared b

American Dyeslulf Reporter U April 1987 Table I: Batch Dyeing Defects Various dye classes exhibit sub A laboratory dyeing which had 90% stantially different behaviors ii exhaustion at equilibrium determined - Physical damage: thermo-dynamic equilibrium (is0 by colorimetric measurements of tender or weak. residual dye in the dyebath, and a Ii. scuffed, pilled, chafed or abraded therm) and kinetics (exhaust 0 fabric strike).'To be successful, dyeing pro quor ratio of 25:l would have: frayed or abraded yarn cedures and equipment must bc picked or snagged fabric compatible with these behaviors. 0 holes, torn, or broken fabric 0 course, individual dyes within a clas! yarn, creases, cracks, breaklines, or ropt may have substantial variation! When the same shade is dyed on pro. marks in fabric which must be considered. Excellen duction machines at 1O:l liquor ratio, presentationsof the fundamentals 0 a value of exhaustion of: - Uneven d e application: exhaust dye applications have beer streaky fa b ric or yarn, shaded goods (sidelside, endlend, published.' For each dye class, then E- = 180 l(180 + 10) = .947 or 9.7% insideloutside, etc.), are certain critical factors to be con blotchy. trolled or special considerations t( be made in order to avoid trouble. Thus to get 1% ye on the goods - Foreign deposits: One particular factor is the manne dye spots, in the laboratory (251 liquor ratio) rE oidetermining amounts of chemicals wax, oil, or size spots, quires 1.11 % dye on weight of good: to be used in exhaust dyeings. The chemical breakout (bath instabi [owg), but in the production machine dye, of course, must be based on the i!Y)# [10:1 liqucy ratio) requires 1.06% dyc f 11t ering deposits. weight of fiber to be dyed. It is coma Dwg. Failure to make an appropriatc mon practice to base amounts of adjustment would result in poor lab chemical auxiliaries also on the xatory-to-dyehouse correlation, ever Table 11: Formulation of Dye Recipe! weight of fabric. This can create if chemicals were based on the problems with shade repeats, for ex. I. Select Equipment: jyebath. Production Volume Expected ample when acid, alkali, or other buf- Another source of variations in dye Cost Requirement (Market Competi fers are used to adjust pH to specific sxhaust is the substitution 01 tlon) ralues or when electrolyte is used. Physical Form of Substrate Slauber's salt for common salt Therefore, quantities of these chem. (GL) Quality (Reproducibility vs. Evenness Several dye classes use salt tc cals should be based on the amount Avallability of Equipment achieve exhaust, and several types oi 3f dye liquor present. Failure to do so salt can be used, including; !. Select Dye Class: s a prominent cause of poor labor- Substrate ( Fiber Content, Blend) atory-todyehouse correlation, as well EquipmentlProcedure Common salt (NaCI) Cost Requirement BS poor shade repeats on odd-sized - Fastness Requirement ots. When liquor ratios vary, basing - GL salt heptahydrate :hemicais on the amount of goods (NalSO'. 7H10) i. i. Select Specific Dyes (within Class): :auses variations in concentrations - GL salt anhydrous (NalSO,) SafetylEnvironmental - Brine (NaClaq) Availability vhich in tum changes the percent ex- cost iaust of dye, therefore affecting Fiber Content of Substrate (eSp. ,hade repeats. Typical laboratory li. Because of the differences of Blends) luor ratios will usually be over.20:1, formula weight between the above, Fastness substitution should not be made on Shade Reproducibility and Evenness thile typical production liquor ratios Required rill be 8:l up to 16:l. equal pound-for-pound basis. Actual Quality Factors (Fastness) Even when chemicals are based on equivalences are: Value, Chroma, Hue of Colorants he bath, changing liquor ratios can ause shade variations. To adjust dye 100# Common salt Match the Color: Percentages of DyeslChemicals to Use ecipes forvariance in liquor ratio re- 122# GL salt anhydrous luires knowledge of the dyeing be- 278# GL salt heptahydrate iaviors described in Part l of this ar- 38.5 gallons brine :eam, which is common practice in Me. In particular, the effective value (23 Be or 25% NaCI) ime drug rooms. If live steam is f "K" in the isotherm (at equilibrium) sed, there is a risk of introducing lust be known for the dyeing. Dye adds letal contamination from the steam One common practice in exhaust 'pes. Also, using live steam can dyeing is the addition of dyestuffs iise the pH of the heated water due (adds) to an exhausted bath in order 1 atbline contaminants in the he liquor ratio L and Kerf are related to adjust a shade which did not pro- eam. It is not unusual to find pH 1 the equilibrium exhaust E by equa- perly repeat. The manner in which values of 8.5 to 9 or higher for water ms 2 and 3. iuch adds are made can substantially which has been heated to 180'F with affect overall dyehouse performance. live steam. If live steam is used, daking adds to production dyeings check frequently to ensure that s difficult at best. The main difficulty metallic contamination and alkalinity which arises is that something, often are not being inadvertently intro- JnknOWn, has caused the shade to fail duced into dye pastes, dyebaths, and o repeat. It could be pH, salt content, washinglscouring operations. :ontamination in raw water, inac-

15 curate weighing of dyes or chemi- propriate properties with regard t cals, poor temperature control, leak- end uses. Exhaust and leveling ar ing drain or fill valve, improper dye or controlled by pH. Traditionally an chemical addition procedure, varia- monium sulfate has been used t tions in substrate preparation, etc. In generate acid in the bath when an many cases, excess dye is still in the monia is released by the reaction: bath and is not exhausted onto the fiber, exhaust (strike) begins very ' fiber. Therefore, nonstandard-dye e rapidly at a specific temperature. haustion has occurred, and the pro1 Also, fabrics which are run in rope er first action is to correct the dyi This does not work well for pH cor form tend to form permanent creases ing as nearly as possible to standar trol on modern enclosed dyeinl if heated or cooled rapidly in the conditions. machines such as jets, beams temperature range near To. If the problem is procedural i package dye machines, and pressun Therefore, it is best to be very con- nature, such as an error in timc becks because the enclosure of thc servative with heating and cooling temperature, pH, salt content or I machine prevents the ammonia fron near To. quor ratio, there is little chance th: escaping. On such equipment, alter Typical TQvalues for acrylics are a dye add will behave any better tha nate buffer systems should be used in the range of 175' to 19O'F, but the the original dyeing. To allow for thi! 'If an acid such as formic or acetic To of wet fiber under tension in the jyers have learned to "hedge" the is used for pH control, additior jye bath may be significantly dif- adds in order not to overshoot. I should be even and slow. Lightfast ferent from the dry To reported by fact, it is rare for a dyer to make ness of acid-dye recipes, which i: :he fiber manufacturers. To repair arge add to correct a shade in on generally very good, can be improv :reases and cracks in acrylic fabrics, :ry; multiple adds are common. Thi ed even further by the addition o ieat 210' to 225'F, run 15 minutes, greatly increases the risk of streak copper sulfate to the dye bath. How hen cool back to well below TQvery )r daqaged goods. To make a gooc sver, copper-containing baths musl ;lowly (0.5'Flminute). lye add requires careful judgment a De handled by special techniques Retarders are frequently used to he exact reason for the failure of thi Such as reuse, to avoid environ, issist in even shade buildup. ;hade to repeat, inspection of thc nental or waste treatment problems ilauber's (GL)salt acts as a mild lyebath for unexhaustea dye, detei Repair procedures for acid dyes in. etarder. Specialty retarders have nination of pH and electrolyte con :lude leveling by boiling (ph must be :trongereffects such as permanent- ent, and determination of whether i :ontrolled in accordance with the y blocking dye sites or complexing lye (color) add is the correct action specific dye selection), or stripping lye in the dye liquor. It is possible to iome things that can be done tc Stripping procedures include reduc. lake a retarder with precisely con- lake adds easier for the dyer are tc ion (zinc sulfoxylatelformaldehyde), rolled action by mixing GL salt with stablish: )xidation (sodium chlorite), or ;pecially ethylene-oxide-tallow- - Good shade repeats in the lab imine stripping agents which have and good lab-to-dyehoust iffinity forthe acid dye and complex correlations; t in solution. The specialty strippers - a reproducible production dyc vork at slightly alkaline pH. provid- recipe and procedure for thc !d by adding TSPP to the bath. Light- shade; astness of stripped and redyed - a dyer's take-off shade guide loods is frequently inferior to first- produced from the same recipe un goods. on the same substrate (no1 finished) for color difference lasic dyes determinations, shade passing, Basic dyes obey the Langmuir and estimating dye adds; and, jotherm when applied to acrylics, - to inspect the dyebath for dye, nd undergo strong, ionic interac- pH, salt content and other fact. ion. Because of the strong affinity of ors before adding color. asic dyes for acrylic (and other asicdyeable) fibers, exhaust is near- Other factors for controlling shade 100% and migration or leveling is epeats and even dyeings are merally poor. Therefore, the selec- )resented below for specific dye 3n of dyes with similar exhaust :lasses. iaracteristics is of primary impor- nce. There are several methods for rcid dyes determining compatibility, including Acid dyes obey the Langmuir AATCCTest Method 141. Other meth- jothem when applied to wool and ods such as "diffusion numbers"' nylon, and undergo strong ionic inter- and affinity determinations' can also action. Acid dyes, as a class, are be used. Careful attention to dye relatively easy to apply. It is im- compatibility is necessary to obtain portant to select dyes with compat- consistent shade repeats, on-tone )ired dyes ible exhaust characteristic and ap- shade build up, and even dyeing. Direct dyes obey the Freundlich

- --. If- __^_,__- ._,'I .e$- I isotherm, when applied to cellulose, mum exhaust temperatures are tures (250.F.) These dyes must bt and undergo weak interaction with shown in Table IV. The practical im- avoided if good shade repeats are tc the fiber. There are three subclasses plications of these temperatures of be obtained, or types of direct dyes. Type A directs maximum exhaust are important. Direct dyeings have inadequate have good migration and leveling pro. Suppose a recipe had for example fastness for many end uses unles: perties even in the presence of salt. CI Directs Red 81, Elue 80, and some sort of fixative is applied Type B directs level well without salt, Yellow 105, which give maximum ex- Several types are commonly used tc but not so well when salt is present. hausts at 140'F, 205'F, and 203'F, improve wet fastness of direct-dyec For this reason, salt addition must be respectively. Ifthe dyeing were done goods. The misuse of fixatives is fre, very carefully controlled, especially at 205'F, the Red 81 would continue quently a contributing factor to off, if brine is used. However, penetration to exhaust during the cooling part of quality direct dyeings. The use 01 and leveling may be achieved with the dye cycle. Thus the fabric sam- copper sulfate has been largely dis. type B directs by boiling the dyebath ple ("hot patch") taken at the dyeing continued because of its detrimental prior to salt addition. Type C directs temperature of 205'F would not con- effects on the environment. Epsom do not level well at all, and evenness tain as much Red 81 as the final (cold) salt is sometimes used as an anti- 31 exhaust must therefore be assured patch. This may lead to poor shade migrant to temporarily fix the dye un- by careful temperature control. Type rep,eats or even worse, unnecessary til a permanent fixative can be ap- 2 are relatively very difficult to dye, dye adds based on an inaccurate hot plied from a continuous finish mix. and exhaust must be controlled by patch. More commonly, resinous fixatives :areful heating. Details of dye proc- When direct dyes are used for are either exhausted from the dye- Csses fordirects such as addition of blends, several special considera- bath or applied in finishing. Improper ialt (hot or cold) and rate of rise must tions must be taken into account. application of these resinous fix- ,e carefully tailored to the dye types One important consideration is the atives can cause spots and streaky, n the recipe. selectionpf dyes with good stability blotchy, or shaded dyeings. The first Important factors in dye selection at high temperature. This is very im- point of concem is never to introduce or directs include type compatibility, portant when dyeing synthetic/ the fixative into a direct-dye bath !xhaust temperature compatibility, cellulose blends together in the same which is not clear of dye. If any dye lead cotton coverage, fastpess, and bath above 212'F. High temperature remains in the bath, adding fixative ,lend considerations (staining). Max- stability of some dyes is given in will immediately precipitate it, mum exhaust temperature for in- Table V. Many direct dyes are hydrol- thereby producing defective goods. lividual direct dyes varies. Examples yzed by slightly-acidic conditions at To clear the bath, many dyers use salt if a few direct dyes and their maxi- extended times and high tempera- in the final rinse. However, many fix- I

atives will precipitate in the presenc of salt, giving resinous spots. 7 Table Ill: Dye Paste Up Practices avoid fixative spots or streaks, tak Add 1 gram per liter thiosulfate if chlorine is present in the water. the following precautions: Add hexaphos if hardness is present in the water. - never add fixative hot; kee Do not use EDTA, DTPA, NTA, or similar sequesterants. temperature around 80' f Be careful when using live steam (pH and metal contamination). 1OO'F while adding fixative; Direct Dyes - be sure the bath is clear of dy Mix dye directly into cool (80.F) water before adding the fixative; With stirring. heat (live steam is OK) to 160'F - if washing in salt, be sure thc Continue stirring until used the fixative is compatible wit salt; Basic Dyes Paste dye in equal weight of acetic acid - heat the dye bath to 140' to er Add dye paste to 2°F water with stirring sure fixative exhaustion, usin Avoid live steam (even before adding dye) a slow, even rate of temper: ture rise; Acid dyes - watch out for chlorine harc . Add dye directly to water with stirring ness, iron, etc. in the waterdu .. . premets, cool (80.F) ing the fixing processing, (ad1 . . . leveling types, hot (180.F) thiosulfate andlor hexaphos i necessary); and Fiber Reactive Dyes Add dye directly to water at 140'F to 170'F with stirring - keep control of the pH accorc Avoid live steam (even before adding dye) ing to values recommended b' Add 70 grams per liter or more of urea to increase solubility the fixative manufacture if solubility problems persist, use liquid dyes. (typically about 4). Direct dyes are commonly appliec Disperse Dyes Add dye to 170' to 115'F water, with stirring vith salt and the amount, type, an( Avoid live steam (even before dye is added) nanner of addition of salt is impor ant to ensure reproducible and leve Vat. Sulfur, Naphthol, Developed, Mordant dyes lyeings. The total amount should bc Follow manufacturer's instructions (varies) . These are usually available as liquids 0 grams per liter of common salt fo ach 1% of direct dye in the recipe lowever, the total amount of com mon salt should not be less than f 'able IV Temperature of Maximum Exhaust for Selected Direct Dyes grams per liter nor more than 4( grams per liter. The amounts shoulc Temp. Temp. CI Direct be based on the bath (not the goods :I Direct ('F) ('FJ and amounts should be properly ad 'ellow 50 140 Blue 1 140 justed if GL salt is used instead 01 'ellow 106 203 'ellow 105 203 Blue 80 205 common salt, as discussec )range 39 175 Blue 218 203 previously. led 81 140 Black 80 212 The amount of electrolyte actually fiolet 4 158 Black 22 212 in a bath can be determined by tech, niques such as conductivity meas. urement, which can easily be done Table V : Stability of Direct Dyes @ 250'F, pH 6 with a pH meter equipped with a con. ductivity probe. Dlrecf Dyes wllh Good Stability Q 250.6 pH 6 Salt must be added evenly and Shade CI Number (Direct) slowly, preferably in 3 to 5 parts. Yellow 8, 11, 12, 27, 28, 29, 98. 105, 106, 114, 127, 137 Great care must be exercised when Orange 34, 37, 57, 107 Red 2. 9, 16... 76, 81, 89, 207 adding brine due to its extreme:y fast Vioiet 49,51 action on the dyebath. A good Blue 2. 71, 76, 77, 80, 86, 90, 98, 160, 191, 218. 224 scheme for fractions in a four-part Green 26. 29. 31. 33 . salt addition are: Brown 2, 95, 113; 200 118 : 118 : 114 : 112; Black 38, 51, 78, 80, 91 allowing .jO minutes between each salt addition This is most critical for type B and C. Some other critical factors to be considered: - Watch the pH

4.5 to 6 for directlbasic - Metals and sequestrants in- )lends); terfere with many directs, I

especially at high temperatu dyes with lower values (less than 20) Test Method 146. The effect of metal (250'F for polyesterlcottc do not level as well. contamination in process water is bI end s). - Dyebath assistants such i lubricants or carriers, levele (for blends) can retard dye e haust andlor affect shac repeats, staining, fastness, et Yellow 54 50 Blue 60 32 Orange 41 If Repair of direct dyeings can t Yellow 67 36 Blue 56 35 qrown 2 2r done only after removal of any fix, Orange 25 32 Yellow 93 34 ...>let 26 2c Red 25 aue 27 tive andlor resin finish from th Orange 44 32 55 1E Red 11 33 Red 59 30 Yellow 42 5 goods. A quick test with carbozol Red 60 36 Red 65 25 Orange 21 4 can detect the presence of finis1 Violet 18 33 Yellow 23 16 Red 135 : After finish removal, dye can be leve Violet 27 33 ed by raising the pH to 8-9with sod ash, boiling down the shade, an then salting back. Stripping can b done with either hydrolsoda ash c hypochlorite depending on the spt Transfer index is determined by reviewed in another article in this cific dye recipe. Some dyes, such a placing a dyed fabric and a mock- series, Water and Textiles Wet Proc- CI Direct Yellow 105 cannot be striF dyed (white) fabric together in a essing-Part 11.' ped satisfactorily. mock-dye bath. Color transfer is Oil spotting, the development of measured as: dye spots due to oil (especially knit- Disperse dyes ting oil) on goods, is especially a Dye desorbed = [(WSbefore- (ws after] I Disperse dyes interact weakly an( problem with colorants such as CI (Wsbefore form solid solutions of dye in syr Disperse Red 60. Spots may also ap- :hetic substrates and follow thl Dye absorbed = (wsltransferl (KWafter pear when dyebath contaminants, Vemst isotherm. Because goods an especially fiber finish, polyester size, Transfer index = [Dye desorbed] x [Dye jyed above TOof the fiber, there is i and/or trimer, precipitate as the absorbed] x 100 -isk of shrinkage, moire, permanen dyebath is cooled. This can be avoid- xeases, cracks, or rope marks where: ed by the use of dyebath auxiliaries ?speciallyif heating and cooling arc (WS)before = color Value of dyed (dis persantslsurfactan t s), or drop p- .apid. A combination of several fact cloth prior to leveling; ing the bath hot (above 19O'F) )rs must be considered to ensun (K/S)after = color value of dyed Disperse dyes are difficult to strip. :ompatibility of the dye recipe especially from polyester. Useful pro- cloth after leveling; and, :hemica1 auxiliaries, substrate ma (WShMsfer = color value of white cedures are excess carrier with either :hinery, and process. These factor: reducing agents (hydrolcaustic) or :an be quantified by any of severa cloth after leveling chlorite (Texton"). Sometimes a se- :ommercial methods23 which takt quential strip with hydrolcaustic nto account: Many dyes, such as CI Disperse followed by chlorite at 250'F is Yellow 42, appear to be bargains in effective. - dyeing speed of fiber; terms of color value for the price, but - timeltemperature of procedure they can present significant leveling Disperseldirect blends - dyestuff characteristics (sub, problems with certain types of ex- When dyeing polyesterlcotton c Iass); Taustdyeing equipment and proc- blends with disperseldirect dye - accelerant (carrier) used; and, zsses. recipes, some important factors must - machine turnoverlrate 01 Some machines, especially those be considered in addition to those heating. Hhich pump the dye liquor, such as presented above for pure substrates: ets, beams and packages, can have iroblems in specific temperature s with other classes, rate coma 'anges due to cloudpoint effects of - disperse-dye leveling agents atibility of all dyes in a recipe is ranionic emulsifier and surfactant and carriers can affect direct ssential for good shade repeats. ;ystems used in many chemical shade repeats and leveling Another important factor in dye ipecialties. This can cause spots, properties; zlectJon is the ability of dyes to )oor crocking fastness, and other - dispersedye carrier can in- ~vecDyes with good leveling proper- lroblems. fluence direct-dye stain on es can be exhausted more rapidly Other commonly encountered polyester, giving poor fastness: ith less chance of streaking the :auses of defects in exhaust dyeing - keeping the pH near 6 is a good iods. The ability of dyes to level can ,f disperse dyes Include filtering of compromise for both dye 5 determined by several methods, lye in package machines and beams, classes; cluding AATCC Test Method #155 netal sensitivity and oil spotting, - disperse dye leveling agent? ' "'transfer index". Leveling ability of loor wash and crocking fastness, and carriers may be sensitive tt !vera1 dyes in typical production Ind dulling of shade by salt (usually salt, especially under condi- ocesses is shown in Table VI. Dyes 3r dyeing blends). Filtering and bath tions of high shear (pumping) ith high values (above 30) level well, tability can be evaluated by AATCC or at specific temperatures;

.,- , - .- ,e-- I

sequestering agents of the Et Table VII: Fiber Reactive Dyeing Methods ! - TA, NTA, or DTPA type may ir Conventional Constant High temperature All-In fluence shade repeats of direc temperature and disperse dyes; and, - lubricants are sometime 1. Set bath and Set bath and Set bath and Set bath and necessary and appropriate, bu load substrate load substrate load substrate load substrate they may infjuence shadl 2. Add dye Add dye Add dye Add dye repeats and evenness. Alsi lubricants may have incorr 3. Run Run Run Run patibility with salt or higl temperatures. 4. Add salt Heat to dyeing Heat to high Add salt temperature' temperature'

'iber reactive dyes 5. Heat to dyeing Add salt Cool to dyeing Heat to dyeing The application of fiber reactivi temperature (*) temperature * temperature ' jyes has a fairly high degree of diffi :ulty compared to other classes 6. Add alkali Run for exhaust Add salt Run for exhaust and reactior Jerhaps one reason for this is thc arge number of choices to be madc 7. Run for reaction Add alkali Run for exhaust Cool :oncerning dye type (hot vs. cold) xocedure (conventional, constan 8. Cool Run for reaction Add alkali Wash emperature, high temperature, or all 9. Wash Cool Run for fixation Apply fixative n), and alkali (bicarb, soda ash, TSP iiiicate, or caustic). Also, the impor IO. Apply fixative Wash Cool ance of procedures after dye ap ,tication, especially washing off anc 11. - Apply fixative Wash ixing, are frequently overlooked i2. - - Apply fixative :iber reactives in general are mor( ldversely influenced by variations ir Typical dyelng 1emp.raIures are 175'F for hot types. l40'F for cold 'Hlgh lemprrtuns ire 203'F fw hot typ.s. 160' lor cold otton, poor preparatibn, "dead" 01 nmature cotton, neps, and othei ubstrate differences than are other ellulosicdye systems. Also, making run consistently on equipment with The conventional procedure gives ye adds to reactive dyeings is fa1 poor temperature controls or in mills good shade repeats and is fairly sim- -lore likely to cause a defective dye- "ith inadequate boiler capacity to ple to run. Penetration and leveling g than are other classes, such as ;upply peak steam demands. are better than the all-in method but rects. The hotdyeing types are usually not as good as the high-temperature The hotdyeing types are less reac- larder to wash off, therefore the method. Good temperature control is vel therefore, require higher washing required after dyeing is essential. !mperatures. They are more stable nore critical. The constant temperature method I hydrolysis and precise temper- Cold dyeing types show more of la- is simple to run and is the most for- ure control is not as critical as for ent defects from preparation. Of giving in terms of temperature fluc- le colddyeing types. Also, penetra- :oursel less energy, salt and alkali tuations. Leveling and penetration m of the dye and leveling is better we required for the colddyeing are better than all-in but not as good ith the hot-dyeing types. ypes, . but without excellent as the high temperature method. Dye cycles are usually shorter with emperature control, these savings The high-temperature method is e colddyeing types, leading to less ire quickly offset by quality losses. more complex, longer to run, and vorking" of the goods. This can Each fiber reactive dye has distinc- consumes more energy, however it ther be good or bad, depending on ive characteristics which influence gives the best penetration and level- e specific situation, the hand IOW it will behave in a particular proc- ing, and is especially useful on prob- !sired, ruggedness of the goods, !ss. These include substantivity and lem styles or poorly prepared goods. c. The cold types are especially sen- eactivity. Figure 2 shows the effect The goods are subjected to more tive to variation in heating rate or of these two factors upon dye ex- physical "work" also; thus the han- action temperature control, there- haustion. Unlike direct dyes, some dle of the fabric is affected and re they are extremely difficult to fiber reactive dyes do not fully ex- physical damage (pitting, or abrasion) haust until alkali is added. Thus the is more likely. Shades generally do manner of addition of alkali is even not repeat as well when this method more critical than addition of salt due is used, however it is not certain to the rapid exhaust that occurs upon whether this poor repeatability is due the addition of alkali as well as the to the method itself or due to the fact that the reactive dye will not level generally poorer preparation of appreciably after alkali addition. The goods for which this procedure is four methods most widely used in designed. commercial dyeing operations for The all-in method is the simplest, fiber reactive dyes are summarized in shortest and least expensive to run Table VII. Table VIII: True-Shade Beck Capacities

Liquor Model 85 Model 850 Depth (inches) -Type 0 Type p Type R Type s Type 0 Type p -Type : 18 52 60 65 75 47 60 70 21 64 74 80 91 58 72 85 24 76 88 95 108 70 85 7 01 27 89 102 110 125 81 98 117 30 102 116 125 142 93 110 133 33 114 129 140 158 105 123 149 36 127 143 155 175 116 136 165 39 139 157 170 191 128 149 182 42 152 171 186 208 140 162 198 15 164 185 201 224 214 18 177 199 216 241 51 189 212 231 258 54 202 226 247 275 j7 215 240 . 262 291 SO 228 254 277 308

Model 85 has straight front - Model 850 has curved front Front to back dimension Type 0 = 7’2”, Type P = 7 ‘11 ”, Type R = 8‘8“, Type S = 9‘5”

~ ~~

I terms of labor, steam, and other dye. Therefore, redyeing of stripped actors. Because the -dye is ex- goods will behave differently than austing, fixing, and hydrolyzing all dyeing of new goods. In particular, t the same time in this method, more alkali and time may be required. hade repeats are poor, dyeings tend > become uneven and streaky un- Equipment ?ss the temperature control is Many different types of equipment lmost perfect. Turnover times for are used for exhaust dyeing. Some le bath andlor fabric must be ade- good general guidelines for various uate to insure even exhaustion of equipment is given below. ie dye, as no leveling will occur. Becks are one of the oldest tradi- his method is extremely risky, over- tional types of equipment for exhaust ‘I, especially with the colddyeing dyeing. Their continued popularity in- ‘pes which react and hydrolyze so dicates the versatility and economy ipidly. of becks. They provide quite a lot of Reactive dyes are sensitive to alka- mechanical action to the fabric. Older linity, chlorine, residual peroxide, and models, which generally lack heat ex- metals. Good water treatment and changers and circulating pumps, fre- #ell-prepared goods are essential. quently have problems with temper- rhorough washing off of unreacted ature differentials (front-to-back, end- jye is important to get good shade to-end) as well as the difficulties ’epeats and level dyeings. On ma- associated with the use of live steam. :hines with poor washing efficiency, These machines cannot be properly iuch as beams, jigs and packagedye heated unless they contain cloth. nachines, fixative should be used to Therefore, any attempt to heat prior wevent migration of dye. More to loading the fabric is futile. vashing is needed when using Since the electrolyte and alkali are ;tronger alkali, such as caustic soda. to be used on the basis of bath iome dyers use potassium hydroxide volume, It is important to know the nstead of caustic) since it washes sxact amount of dye liquor in the iff easier. Fixative handling pro- beck. This can be determined either edures should. be the same as with a water meter or by the use of iscussed under direct dyes. commonly available tables like Table Use of hydrolcaustic or hypochlor- VIII. An audit checklist for mechani- e will generally result in a complete cal condition of becks is presented tripping of reactive color. However, in Table IX. An operations checklist ye sites on the cellulose may remain for becks is shown in Table X. Care- locked due to residual fragments of ful attention to these details through Figure 2

Exhaust and Fixation of Fiber Reactive Dyes

a Salt addition Alkali addition preventive maintenance and good su- ty. Pressure becks have a few addi- pressure leaks which cause boiling pervision will pay dividends in quali- tional points of concern, primarily and tangles. Equipment factors to minimize migration. To avoid crocking problems with Modern package and beam-dyeing Beam-dyeingmachines have many certain disperse reds on polyester equipment have extremely high bath features similar to package dyeing (especially Disperse Red 53,60,132, turnover. Because of this, bath machines. Batching is critical, and 131, and 159), drop the bath hot. Thi: stability is critical. Instability of the should begin with eight or more will help to avoid crystallization OL dyebath due to shearing action of layers of lapping cloth to avoid per- these disperse dyes when the bath high speed pumps, high temperature foration marks. Uniform batching cools. Dye paste-up procedures and or rate of rise, short liquor ratio, prevents shade variations within the bath stability are critical for beam cloudpoint, or chemical incom- load and should be done with moder- dyeing just as for package dyeing. patibility will lead to filtering and ate tension. If tension is too high, Jet dyeing machines have many deposits. Because of the higher flow moire, low flow or blown beams will advantages over other equipment. rates, winding is more critical for new result; if too low, channeling and including: machines than for older, lower-flow uneven dyeing will result. Winding - better heat distribution; machines. Acceptable flow rates are tension should be adjusted to allow - higher turnover rate which in the range of 3 to 5 gallonslminute for shrinkage if appropriate. Winding allows use of brine and faster per pound of load. Filtering problems should extend 2 to 4 inches beyond rate of rise; and, usually can be traced to water perforations on beam with side-to- - does not have bath stability (sediments, alum, hardness), trimer side movement to compensate for problems like package and or fiber finish, or bath instability excessively large selvage buildup, if beam machine. (shear, temperature, cloudpoint or necessary. chemical compatibility). Subst rate Problems which can arise with jet contaminants such as metals, trimer, dyeing include harsh action and mxes and oils, residual bleach or Effect of moire fabric distortion of some machines, alkali'can create problems. Drying of If moire develops, wind looser and tangles which can result from foam- 3ackage-dyed yarn should be done run shorter OlI times. Pretreatment of ing due to certain dyes or excessive xomptly within 4 to 6 hours to avoid lightweight polyester fabrics with use of chemical auxiliaries, bath nigration of dye. A good extraction caustic (6 to 8% owg) reportedly breakouts from shearing or tempera "blow-down") cycle will save energy helps avoid moire. To correct moire ture effects, and shading port-to-port is well as reduce dye migration. Fix- 3n polyester, run at 240'F for 30 min., due to uneven strand length. One ttives can be used on fiber reactives Nith carrier. common error in jet-dyeing practice I

Table IX: Beck Audit-Mechanical IConlinued from page 261 References Inspection is the excessive use of chemical (1) AATCC Technical Manual, AATCC, specialty-dyeing assistants. Usually Research Triangle Park, NC (1987). Reel type, shape, cover, speed- 1 very few chemical specialties are (2) The Resolina S Process, Mobay, Rock ' compatible with substrate and dye recipe Hill, SC. needed. (3) Smith, Brent, "Troubleshoofing in Dye. 1 Idler reel-turns free and true ing, Part I-General," in Press (ADR) 'Snags' or rough edges in the machine Conclusion (4) Dyeing Primer Pan I - XII, Textile Chemist and Colorist, January through Tangle detector-rake and reel overload It is beyond the scope of this or December, 1980. Tangle alarm-audible and visible any other single article to specifical- (5) Diffusion Numbers of Palanile Dyes, ly address all possible troubleshoot- BASF, Charlotte. NC. Controller accuracy-temperature an( ing situations in batch dyeing. But (6) Shipmann, E.J., "Affinity of Cationic rate of rise this article is intended to provide Dyes for Acrylics, Textile Chemist and Leaking valves-drain, fill, steam types Colorist. 7, no. 3 (March 1975). some means of accomplishing prob- (7) Smith, Brent, and Rucker, James, Steam quality available (while othe lem solving in a wide variety of batch "Water and Textile Wet Processing- demands are "on") dyeing operations. 0 0 0 Part 11." in Press (ADR). Circulating pump and heat exchanger (il any)-performance at operatins temperature Location and integrity of temperatun sensor Location and evenness of steam injection for heating When heating and also when holding al 140' and 200*F, front-to-back and end-to end temperature differences Dverhead steam (if any) lamper and door (front and rear) operation lerify damper ability to exhaust fumes -ill water temperature rable X: Beck Operations Checkti5

root (typical) Long strands dye light, short strand dye dark, be sure all of the strand are the same length Load out fully and evenly Sew seams straight, no twist 11 strands, no holes in seam Control the liquor level according t( the fabric; too high gives tangles anc "swimming" of cloth, too low give: abrasion, streaks, blotchy dyeing Schedule light shades first, darl shades later Base electrolyte and buffer on the bath, not the cloth Ensure moderate ballooning b) allowing some foam or air to colleci inside tubular goods-inflate witP airhose if needed Be sure to take a slow rate of rise near the cdtical points, such as we1 To and dye strike temperature ' Don't boil a beck-tangles will result Use overhead steam to prevent drips