COLOURFASTNESSTOWASHINGANDCOLOUR FASTNESSSTOWATER Whenaconsumerbuystextilessuchasclothingfabric,bedlinen,homefurnishingsoranyother related material, he or she expects it to perform satisfactorily during use in terms of colour stability and appearance retention, including shape, pilling/ fuzziness etc. The problems associatedwithdurabilityofcolourandappearanceonwettreatmentssuchaswashingandwet rubbing are of global nature, which in turn frequently leads to consumer dissatisfaction and complaints. TheresultsofrecentconsumerresearchinWesternEuropehasindicatedthatoneoftheprimary reasonsforcustomerdissatisfactioniscolourfadingduringwashingandstainingofotherarticles. Thefollowingfactorsareconsideredimportantinthecolourfastnesstowashingoffabrics Washingmachinesandwashingprogrammes. Use of wash loads consisting of whites and coloured merchandise made from differentfibrematerials,suchascotton,polyester,nylonetc. Low energy programmes in washing machines low liquor, low temperatures and higherdetergentactivity. Additivesindetergentformulations. Inthequalitycontroloftextiles,twotestsarecommonlyusedinthespecificationstodetermine colourfastness properties. One is Colourfastness to Washing and the other Colourfastness to Rubbing.Oftenanimportanttestismissed ColourfastnesstoWater. ColourfastnesstowashingmaybeconductedasperISO105C06orAATCC61standardswhile ColourfastnesstowaterisconductedtoISO105E01orAATCC107.Testmethodsareselectedin accordancewiththebuyer sspecifications. ColourfastnesstoWashing: Colourfastness to washing is a test, which simulates the home laundering practices that a consumerwoulduse. These are accelerated washing tests that are roughly equivalent to five or more home or commerciallaunderings.specimensofastandardareattachedtomultifibrestrips,washedand thereafterevaluated. Washing is performed in canisters placed in a machine called a launderometer. Standard referencedetergentsolutionsareusedforthetestingandthewashliquormayhaveadditivessuch as sodium perborate. The detergent solution is made in distilled or dionized water. AATCC StandardReferencedetergentorECEReferenceDetergentwithoutopticalbrightenersneedstobe usedforthistest. ColourfastnesstoWashingandWater 1
SteelBallsprovidethenecessaryabrasionandagitationintesting.Testsareconductedfor30or 45minutes. Evaluation includes the change in shade of the washed fabric and staining on multifibre fabric, performed in a standard assessment light box. Rating is given using a Grey Scale between 1 (Worst)and5(Best). ColourfastnesstoWater: ColourfastnesstoWateristhetestthatdeterminesthephysicalmigrationofcolourfroma colouredsubstratetoanotherwhenwetandinintimatecontact. Thistestmethodisdesignedtoevaluatetheresistancetowaterofcolouredmaterials.Aspecimen ofstandardsize(4x10cmforiso,2x4inchesforaatcc)isattachedtoasimilarsize multifibrestrip,immersedinwater,placedbetweenglassoracrylicplatesunderspecifiedpressure and temperature for aspecific time period. The change in colour andstaining on multifibre is evaluated. ThetestusesaPerspirometerwhichisplacedinanincubatoroven.TheISOtestisdoneat37± 2ºCfor4hourswhiletheAATCCtestisperformedat38±1ºCfor18hours.Oncompletionof time, the specimens are removed; air-dried and evaluated in a standard assessment light box. Ratingisonagreyscalebetween1(Worst)and5(Best). Arethetestscomplementary? Whilemostpersonsthinkthesetestsrepresentthesamepropertyofthespecimengivingsimilar results,theyarenot.testresultscanbeverydifferentforthetwoprocedures. Thisisillustratedintheexamplesbelow.Pleasealsoseethesampledisplays. Fabric1 Inthisdyedfabric,theshadechangeisrated4to4-5forbothwashingandwaterfastness. However,thereisconsiderablestainingoncotton(1-2)inthecolourfastnesstowashing whereasthereispracticallynostainingincolourfastnesstowater. Inthiscase,thedyedfabricissensitivetopHandunderalkalineconditionsofthewashing, thedyebleedsandstainstheadjacentmultifibrefabric.however,incolourfastnessto Water,whichisataneutralpH,nosuchstainingisobserved. Fabric2 Inthismaterial,theColourfastnesstowashingisexcellent,butthecolourfastnesstowateris verypoor. Thefabricinthiscaseisprintedwithreactivedyesandalthoughthereislooseunfixedreactive dyeonthefabric,itdoesnotstainthemultifibrefabric,asthishydrolyzeddyehasnoaffinity foranyofthefibres. ColourfastnesstoWashingandWater 2
Whenthesamematerialcomesintointimatecontactwiththemultifibrefabricinthe colourfastnesstowatertest,thelooseunfixedreactivedyemigratesandstainsthemultifibre strongly. Fabric3 Thisfabricalsoshowspoorcolourfastnesstowaterwhilethecolourfastnesstowashingis good. Inthiscaseagain,theloosedyestuffpresentishydrolyzedanddoesnotshowstainingofthe adjacentmultifibrefabric.however,considerablestainingincolourfastnesstowateris observedduetomigration. ThefirstexampleshowstheproblemisprimarilyduetopHsensitivityofthedyesusedinthe fabricwhiletheothertwohavepoorcolourfastnesspropertiesduetohydrolyzeddyenot removedduringprocessing. Conclusion Itcanbereadilyseenfromtheexamplesabovethatitisabsolutelynecessarytoundertakethe testsof COLOURFASTNESSTOWASHINGand COLOURFASTNESSTOWATER ifwearetoaccuratelypredictpotentialcolourfastnessproblemstopreventcustomer complaints,claimsandrejections. ColourfastnesstoWashingandWater 3
Examples: s: FABRIC 1 Fabric1 ColourfastnesstoWashingandWater 4
Change in shade : 4-5 4 1-2 2-3 3-4 4 3 FABRIC2 ColourfastnesstoWashingandWater 5
FABRIC3 ColourfastnesstoWashingandWater 6