Designation:D2131−97(Reapproved2016)StandardClassificationforNaturalMuscoviteMicaSplittings1ThisstandardisissuedunderthefixeddesignationD2131;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisspecificationcoversthedeterminationofmuscovitemicasplittingsofstandardcommercialgradesandspecifiesthemaximumallowablephysicaldefectsforeachgrade.Itisapplicabletocommerciallyavailablenaturalmuscovitemicasplittingsregardlessofthebasiccolorofthemicaoritssource.1.2Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.3ThisstandardisverysimilartoISO6386.Itisexpectedthatmaterialswouldbeclassifiedidenticallyusingthecriteriaofeitherstandard.Thegradesshownunder“ASTMGradeNo.”inTable1andTable2areshownunder“OldGradeNo.”inISO6386-1981.2.ReferencedDocuments2.1ASTMStandards:2D351ClassificationforNaturalMuscoviteBlockMicaandThinsBasedonVisualQualityD1711TerminologyRelatingtoElectricalInsulation2.2ISOPublications:ISO6386-1981MuscoviteMicaSplittings—GradingandVisualClassification33.Terminology3.1Fordefinitionsrelatingtomicaandfortermsapplicabletothisstandard,refertoTerminologyD1711,andClassifica-tionD351.4.Classification4.1Micasplittingsareclassifiedbysize,form,andvisualqualityandproperties.4.2Thirteengrades,basedonsizeandform,aredescribedasgiveninTable1.4.3Withinthegrades,uptothirteencategoriesofvisualqualitymaybeseparatelyspecified,aslistedinSection6.Notallofthevisualqualitycategoriesareavailableinallgrades.5.PhysicalProperties5.1NaturalmuscovitemicasplittingsshallmeetthesizerequirementsspecifiedinTable1.ClassificationD351,Table1andFig.1,definemorecompletelytheareasandminimumdimensionsthatdefinethesizegrades,andwhichshouldbeusedinconjunctionwithTable1ofthisspecification.5.2Thereshallnotbemorethanthemaximumallow...
