Designation:D5796−10(Reapproved2015)StandardTestMethodforMeasurementofDryFilmThicknessofThin-FilmCoil-CoatedSystemsbyDestructiveMeansUsingaBoringDevice1ThisstandardisissuedunderthefixeddesignationD5796;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthemeasurementofdryfilmthickness(DFT)ofcoatingfilmsbymicroscopicobservationofaprecision-cut,shallow-anglecraterboredintothecoatingfilm.Thiscraterrevealscrosssectionallayersappearingasrings,whosewidthisproportionaltothedepthofthecoatinglayer(s)andallowsfordirectcalculationofdryfilmthickness.1.1.1TheApparatus,Procedure,andPrecisionandBiasdiscussionsincludeMethodAandMethodB.MethodAinvolvestheuseofanopticalmeasurementapparatuswhichisnolongercommerciallyavailable,butremainsavalidmethodofdryfilmmeasurement.MethodBisasoftwaredrivenmeasurementprocedurethatsupersedesMethodA.1.2Thesubstratemaybeanyrigid,metallicmaterial,suchascold-rolledsteel,hot-dippedgalvanizedsteel,aluminum,etc.Thesubstratemustbeplanarwiththeexceptionofsubstratesexhibiting“coilset,”whichmaybeheldlevelbytheuseoftheclampingtoolonthedrillingdevice.NOTE1—Variationsinthesurfaceprofileofthesubstratemayresultinmisrepresentativeorganiccoatingthicknessreadings.Thisconditionmayexistoversubstratessuchashot-dipped,coatedsteelsheet.Thisistrueofall“precisioncut”methodsthatareusedtodeterminedryfilmthicknessoforganiccoatings.Thisiswhyseveralmeasurementsacrossthestripmaybeusefulifsubstratesurfaceprofileissuspect.1.3Therangeofthicknessmeasurementis0to3.5mils(0to89µm).NOTE2—ForDFTmeasurementsoffilmsgreaterthan3.5mils(89µm),butlessthan63mils(1600µm),a45°borermaybeusedinaccordancewiththistestmethod,withtheexceptionof6.8,wherethemicrometerreadingwouldprovideadirectread-out,anddivisionbytenwouldbeunnecessaryper4.3.1MethodA.1.4Measureme...
