ASTM_D_2134_-_93_2012.pdf

Designation:D213493(Reapproved 2012)Standard Test Method forDetermining the Hardness of Organic Coatings with aSward-Type Hardness Rocker1This standard is issued under the fixed designation D2134;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 determination of the relativedegree of surface hardness of organic coatings using a specificapparatus widely used in the coatings industry.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This test method does not purport to address all of thesafety problems,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1186 Test Methods for Nondestructive Measurement ofDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base(Withdrawn 2006)3D1400 Test Method for Nondestructive Measurement of DryFilm Thickness of Nonconductive Coatings Applied to aNonferrous Metal Base(Withdrawn 2006)3D3924 Specification for Environment for Conditioning andTesting Paint,Varnish,Lacquer,and Related MaterialsD4138 Practices for Measurement of Dry Film Thickness ofProtective Coating Systems by Destructive,Cross-Sectioning Means3.Significance and Use3.1 Sward-type hardness rocker instruments have been usedby the coatings industry for more than a half a century as anondestructive test instrument to measure cure and ultimatesurface hardness of organic coatings(see Refs.(1)through(11).4An accepted standard test method for the use of such aninstrument is long overdue.3.2 In previous task group work designed to establish anASTM method for measuring hardness of organic coatingswith Sward-type hardness rocker instruments,round-robin testresults continually showed poor interlaboratory reproducibility.This lack of interlaboratory agreement could have resultedfrom dimensional variations among instruments,with thecontact rocker rings as the most likely offender in that regard.There are several producers of Sward-type hardness rockersmaking instruments that differ among themselves in net weightand ring radius.Some of them exceed the measurements andnet weight called for in this test method.3.3 This test method,however,is useful within laboratoriesto quickly screen and measure the surface hardness of candi-date coatings.4.Apparatus4.1 Hardness TesterThe hardness tester shall consist oftwo flat,chromium-plated bronze rings with uniformly roundoutside edges.These rings are separated and held in positionwith a weighted lower member and three horizontal light-weight spacer bars with the topmost one supporting a weightadjustable in height.A rack across the center section supportstwo bubble tube-type levels that are used to measure theamplitude of the oscillations of the hardness tester.The rate of1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1962.Last previous edition approved in 2007 as D2134 93(2007).DOI:10.1520/D2134-93R12.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.4Boldface numbers in parentheses refer to the list of references at the end of thistest method.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 change in amplitude is used as a measure of hardness orsoftness of the test surface.The hardness tester shall meet thefollowing characteristics:Weight100 10 gDiameter10 0.025 cm(4.000 0.010 in.)Width betweenrings2.5 0.0125 cm(1.000 0.005 in.)Period50 swings on glass plate in 60.0 0.5 sCalibrationDecrease in amplitude of 6 taken betweenapproximately 22 and 16 from the vertical,after50 swings on glassThe hardness tester should be equipped with a clear cover toprotect it from air currents during operation.Asuitable tester isillustrated in Fig.1.4.2 Glass PlatesGlass panels approximately 15cm2(6in.2)and a minimum of 2 mm(78 mils)thick are required.Preferably these should