ASTM_D_772_-_18.pdf

Designation:D77218Standard Test Method forEvaluating Degree of Flaking(Scaling)of Exterior Paints1This standard is issued under the fixed designation D772;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers the evaluation of the degree offlaking(scaling)of exterior paints by comparison with photo-graphic standards.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 is similar though not identical to ISO4628 Part 5.ISO 4628 Part 5 uses a 0 to 5 rating scale,wherea rating of 0 is no change and a rating of 5 is most severe.TestMethod D772 uses a 10 to 0 rating scale,where a rating of 10is no change and a rating of 0 is most severe.The two standardsuse different pictorial reference photographs for determiningthe rating values.1.4 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.1.5 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 Other Standards:2ISO 4628 Part 5Paints and VarnishesEvaluating theDegradation of CoatingsDesignation of Quantity andSize of Defects,and of Intensity of Uniform Changes inAppearancePart 5:Assessment of Degree of Flaking3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 flaking,nthat phenomenon manifested in paint filmsby the actual detachment of pieces of the film itself either fromits substrate or from paint previously applied.In this standard,the terms flaking and scaling are considered synonymous.Refer to 6.2.3.3.1.1.1 DiscussionFlaking is generally preceded by crack-ing or checking or blistering,and is the result of loss ofadhesion,usually due to stress-strain factors coming into play.4.Significance and Use4.1 Flaking failure of paint films can occur in use.This testmethod provides a means of evaluating the degree of failure bycomparing to pictorial standards.5.Type of Flaking5.1 Only one type of flaking is recognized,as defined inSection 3.6.Use of Photographic Reference Standards6.1 The photographic reference standards that are part ofthis test method are representative of the degree of flaking ofexterior paint films.6.2 The use of the photographic reference standards illus-trated in Figs.1-4 requires the following precautions:6.2.1 Care must be taken not to confuse various types offailure that may be present on the same surface.6.2.2 It must be realized that degree of failure will vary overany given area.Therefore,an average portion of the filmshould be used for comparison.On larger surfaces it isrecommended that ratings be made at several locations and themean and range reported.6.2.3 In technical literature,a distinction is sometimes madebetween flaking and scaling.In most cases,however,flakingand scaling refer to the same phenomenon.In some instances,the term flaking is used to describe the detachment of pieces offilm less than 6.4 mm(14in.)in size,and scaling,thedetachment of pieces over 6.4 mm(14in.)in size.In otherinstances,the term flaking is used to describe the detachmentof pieces of film from the immediate undercoat(intercoatfailure)and scaling the detachment of pieces from the base1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.25 on Evaluation of Weathering Effects.Current edition approved Sept.1,2018.Published October 2018.Originallyapproved in 1944.Last previous edition approved in 2011 as D772 86(2011).DOI:10.1520/D0772-86R18.2Available from U.S.National Committee of the CIE(International Commissionon Illumination),C/o Alan Laird Lewis,282 E.Riding,Carlisle,MA 01741,http:/www.cie-usnc.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 Trad