Designation:D7488−11(Reapproved2016)StandardTestMethodforOpenTimeofLatexPaints1ThisstandardisissuedunderthefixeddesignationD7488;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversaproceduretodeterminethelengthoftimealatexpaintremains“wet”or“open”enoughtoallowforbrush-inandrepair.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D3924SpecificationforEnvironmentforConditioningandTestingPaint,Varnish,Lacquer,andRelatedMaterialsD5068PracticeforPreparationofPaintBrushesforEvalu-ationD5301PracticeforPhysicalCharacterizationofPaintBrushesE177PracticeforUseoftheTermsPrecisionandBiasinASTMTestMethodsE691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod3.Terminology3.1Definitions:3.1.1opentime,n—thelengthoftimeacoatingremainswetoropenenoughtoallowforbrush-inwithouttheedgesofthefirstcoatbecomingvisibleandallowingforrepairwithinthepreviouslypaintedarea.4.SummaryofTestMethod4.1Sinceenvironmentalconditionssuchastemperature,humidityandairflowcanresultinvariableresults,itisrecommendedthatthistestmethodbeperformedinaconstanttemperature/humidityroom(2362°C(73.563.5°F))/5065%relativehumidity.Testpaintsareappliedtothecenterofasealedchartwitha76microns(3mil)wetfilmthickness.Xmarksaremadeimmediately.ThenumberofXmarkswilldependonhowmanycanfitononedrawdown(seeFig.1).Thetestpaintisthenappliedinperpendicularsections,brushingeachsectionacrosstheinitialpaintedsection.Theperpendicu-larsectionsarerepeatedatagreedupontimeintervals.Afterdrying,wetedgeisrecordedasthelasttimethetestpaintcouldbebrushe...
