ASTM_D_6677_-_18.pdf

Designation:D667718Standard Test Method forEvaluating Adhesion by Knife1This standard is issued under the fixed designation D6677;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 procedure for assessing theadhesion of coating films to substrate by using a knife.1.2 This test method is used to establish whether theadhesion of a coating to a substrate or to another coating(inmulti-coat systems)is at a generally adequate level.NOTE1The term“substrate”relates to the basic surface on which acoating adheres(may be steel,concrete,etc.or other coating).1.3 This method can be used in the laboratory and field.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 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.1.6 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:2D2197 Test Method for Adhesion of Organic Coatings byScrape AdhesionD3359 Test Methods for Rating Adhesion by Tape TestD4138 Practices for Measurement of Dry Film Thickness ofProtective Coating Systems by Destructive,Cross-Sectioning MeansD4541 Test Method for Pull-Off Strength of Coatings UsingPortable Adhesion TestersD6132 Test Method for Nondestructive Measurement of DryFilm Thickness of Applied Organic Coatings Using anUltrasonic Coating Thickness GageD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous MetalsD7234 Test Method for Pull-Off Adhesion Strength of Coat-ings on Concrete Using Portable Pull-Off Adhesion Tes-ters3.Summary of Test Method3.1 Adhesion is determined by scribing an“X”into thecoating film to the substrate and by lifting the coating with thepoint of a utility knife.Adhesion is evaluated qualitatively ona 0 to 10 scale.4.Significance and Use4.1 Coatings,to perform satisfactorily,must adhere to thesubstrates on which they are applied.This test method has beenfound useful as a simple means of assessing the adhesion ofcoatings.Although this method is a qualitative(subjective)testit has been used in industry for many years and can providevaluable information.4.2 Other adhesion test methods may be useful in obtainingquantitative results.See Test Methods D2197,D3359,D4541,and D7234.4.3 The Performance Evaluation Scale(see Table 1)isbased on both the degree of difficulty to remove the coatingfrom the substrate and the size of removed coating chip.4.4 This test method does not have a known correlation toother adhesion test methods(pull-off,tape,etc.).4.5 A coating that has a high degree of cohesive strengthmay appear to have worse adhesion than one that is brittle andhence fractures easily when probed.4.6 This method is not to be used on overly thick coatings,that is,those which cannot be cut to the substrate with a utilityknife in one stroke.5.Apparatus and Materials5.1 Cutting ToolSharp utility knife.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved June 1,2018.Published June 2018.Originallyapproved in 2001.Last previous edition approved in 2012 as D6677 07(2012).DOI:10.1520/D6677-18.2For 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.1 5.2 Cutting GuideSteel or other hard metal straight edgeto ensure straight cuts.5.3 Dry Film Thickness Gage.6.Test Specimen6.1 When this test method is used in the field,the specimenis the coated substrate on which the a