Designation:D2620–87(Reapproved1995)e1StandardTestMethodforLightStabilityofClearCoatings1ThisstandardisissuedunderthefixeddesignationD2620;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.e1NOTE—KeywordsandunitofmeasurementstatementwereaddededitoriallyinMay1995.1.Scope1.1Thistestmethodcoversthedeterminationofthediscol-orationofclearcoatingsbysunlightthroughglass.1.2Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D1729PracticeforVisualEvaluationofColorDifferencesofOpaqueMaterials2D1925TestMethodforYellownessIndexofPlastics3G24PracticeforConductingExposurestoDaylightFil-teredThroughGlass43.SummaryofTestMethod3.1Theeffectofsunlightondiscolorationofclearcoatingsisdeterminedbyexposingunderglass,coatedpanelsmaskedatoneend,tonaturalsunlightforaspecifiedtime.Attheendoftheexposure,themaskisremovedandthepanelsevaluatedfordegreeofdiscoloration.4.SignificanceandUse4.1Colorchange,particularlyyellowing,isnotgenerallyacceptabletousersofcoatingswhenitisreadilynoticeable.Indesigningclearcoatingsystemsforinterioruseonvarioussubstrates,itisofinteresttoknowhowwelltheclearcoatswillresistcolorchangecausedbyambientlight.Thistestmethodpermitstheevaluationoftheeffectofnaturalindoorlightonthecolorstabilityofclearcoatings.5.Apparatus5.1ExposureCabinetasdescribedinPracticeG24.6.TestSpecimens6.1Foreachclearcoatingundertest,useonetestpanelapproximately3by5in.(75by125mm)ofwhitecarraraglassorotherspecifiedsubstratematerial.NOTE1—Othermaterialsthatmaybec...
