ASTM_D_5178_-_21.pdf

Designation:D517821Standard Test Method forMar Resistance of Organic Coatings1This standard is issued under the fixed designation D5178;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.Scope*1.1 This test method covers the determination of the marresistance on smooth,flat surfaces.Results are expressed interms of force-to-mar films of organic coatings such as paint,varnish,and lacquer when applied to smooth,flat planar panelsurfaces.1.2 UnitsThe values stated in inch-pound units are to beregarded as standard.The values given in parentheses aremathematical conversions to SI units that are provided forinformation only and are not considered standard.1.3 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.1.4 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:2D609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating ProductsD823 Practices for Producing Films of Uniform Thicknessof Paint,Coatings and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD2691 Method for Microscopical Measurement of Dry FilmThickness of Coatings on Wood Products(Withdrawn1992)3D7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous MetalsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 mar resistance,nthe ability of a coating to resistdamage caused by light abrasion;it is a resistance of thesurface of the coating to permanent deformation,resultingfrom the application of a dynamic mechanical force.4.Summary of Test Method4.1 The materials under test are applied at uniform thicknessto flat panels of uniform surface texture.After drying/curing,the mar resistance is determined by pushing the panels beneatha loop stylus at a constant normal load.Increasing(decreasing)loads are applied to the stylus until the coating is marred(notmarred).5.Significance and Use5.1 In some situations,marring of coatings applied tosubstrates under typical use conditions is unacceptable.Thistest method has been found useful in differentiating the degreeof marring of coatings on substrates.It is most useful inproviding relative ratings for a series of coated panels exhib-iting significant differences in marring.5.2 In a limited laboratory study,meaningful mar resultswere impossible when powder coatings were tested.The marmarking,that is,scratches,became less perceptible with time.Therefore,powder coatings may not be applicable coatings forthis test method.6.Apparatus6.1 Application Equipment,as described in Practices D823.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved June 1,2021.Published June 2021.Originallyapproved in 1991.Last previous edition approved in 2016 as D5178 16.DOI:10.1520/D5178-21.2For 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.*A Summary of Changes section appears at the end of this standardCopyright 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.16.2 Film-Thickness Measuring Apparatus,as described inTest Methods D1005,D2691,or D7091.6.3 Balanced Beam Scrape Adhesion and Mar Tester(Fig.1and Fig.2),consisting of a balanced beam to which i