Designation:B555−86(Reapproved2013)StandardGuideforMeasurementofElectrodepositedMetallicCoatingThicknessesbyDroppingTest1ThisstandardisissuedunderthefixeddesignationB555;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidecoverstheuseofthedroppingtesttomeasurethethicknessofelectrodepositedzinc,cadmium,copper,andtincoatings.NOTE1—Undermostcircumstancesthismethodofmeasuringcoatingthicknessesisnotasreliableorasconvenienttouseasanappropriatecoatingthicknessgauge(seeTestMethodsB499,B504,andB568).1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2B487TestMethodforMeasurementofMetalandOxideCoatingThicknessbyMicroscopicalExaminationofCrossSectionB499TestMethodforMeasurementofCoatingThicknessesbytheMagneticMethod:NonmagneticCoatingsonMagneticBasisMetalsB504TestMethodforMeasurementofThicknessofMetal-licCoatingsbytheCoulometricMethodB568TestMethodforMeasurementofCoatingThicknessbyX-RaySpectrometryD1193SpecificationforReagentWater3.SummaryofGuide3.1Adroppingtest3consistsofapplyingdropwiseacorro-sivesolution,ataconstantrate,totheelectroplatedsurface,andmeasuringthetimerequiredtopenetratethecoatingandexposethesubstrate;thistimeisproportionaltothecoatingthickness.4.SignificanceandUse4.1Thethicknessofametalcoatingisoftencriticaltoitsperformance.4.2Thisprocedureisusefulforanapproximatedetermina-tionwhenthebestpossibleaccuracyisnotrequired.Formorereliabledeterminations,thefollowingmethodsareavailable:TestMethodsB487,B499,B504,andB568.4.3Thistestassumesthattherateofdissolutionofthecoatingbythecorrosivereagentunderthespecifiedcondition...
