ASTM_D_5796_-_20.pdf

Designation:D579620Standard Test Method forMeasurement of Dry Film Thickness of Thin-Film Coil-Coated Systems by Destructive Means Using a BoringDevice1This standard is issued under the fixed designation D5796;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of dry filmthickness(DFT)of coating films by microscopic observation ofa precision-cut,shallow-angle crater bored into the coatingfilm.This crater reveals cross sectional layers appearing asrings,whose width is proportional to the depth of the coatinglayer(s)and allows for direct calculation of dry film thickness.1.1.1 The Apparatus,Procedure,and Precision and Biasdiscussions include Method A and Method B.Method Ainvolves the use of an optical measurement apparatus which isno longer commercially available,but remains a valid methodof dry film measurement.Method B is a software drivenmeasurement procedure that supersedes Method A.1.2 The substrate may be any rigid,metallic material,suchas cold-rolled steel,hot-dipped galvanized steel,aluminum,etc.The substrate must be planar with the exception ofsubstrates exhibiting“coil set,”which may be held level by theuse of the clamping tool on the drilling device.NOTE1Variations in the surface profile of the substrate may result inmisrepresentative organic coating thickness readings.This condition mayexist over substrates such as hot-dipped,coated steel sheet.This is true ofall“precision cut”methods that are used to determine dry film thicknessof organic coatings.This is why several measurements across the stripmay be useful if substrate surface profile is suspect.1.3 The range of thickness measurement is 0 to 3.5 mils(0to 89 m).NOTE2For DFT measurements of films greater than 3.5 mils(89m),but less than 63 mils(1600 m),a 45 borer may be used in accordancewith this test method,with the exception of 6.8,where the micrometerreading would provide a direct read-out,and division by ten would beunnecessary per 4.3.1 Method A.1.4 Measurements may be made on coil-coated sheet,cer-tain formed products,or on test panels.1.5 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D3794 Guide for Testing Coil Coatings3.Significance and Use3.1 Measurement of dry film thickness of organic coatingsby physically cutting through the film and optically observingand measuring the thickness offers the advantage of directmeasurement as compared with nondestructive means.3.2 Constituent coating layers of an overall thickness of acoating system can usually be measured individually by thistest method,provide adhesion between each layer is sufficient.(However,this can be difficult in cases where the primer,topcoat,or multiple coating layers have the same,or verysimilar,appearance.)1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved July 1,2020.Published July 2020.Originally approvedin 1995.Last previous edition approved in 2015 as D5796 10(2015).DOI:10.1520/D5796-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.4.Apparatus4.1 Dry Film Thickness Device,3It is an apparatus consistingof either a manual or automated carbide-tipped drill that raisesand lowers the boring tip perpendicular to the surface to betested,a cleaning brush,a marking device(optional),and avideo imaging syste