1、Designation:D778613(Reapproved 2019)Standard Test Method forDetermining Enamel Holdout1This standard is issued under the fixed designation D7786;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 pa
2、rentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This standard provides a method for determining theholdout characteristics of a primer and topcoat coating appli-cation.A standard topcoat is used to d
3、etermine the absorptioncharacteristics of a primer.Enamel holdout can be measured asa difference in observed gloss of the topcoat over a primer,relative to the gloss of the same topcoat over a non-porous,smooth surface.1.2 The standard is written in the context that the user willbe evaluating the en
4、amel holdout characteristics of a primer.Alternatively,the standard may be used as a method to evaluatethe enamel holdout characteristics of primer/topcoat systemwhere the primer is constant and different topcoats are used astest paints.1.3 This standard may also be used for evaluation of paintsothe
5、r than primers as the first coat.In this alteration the usercan test the enamel holdout characteristics of a self-primedtopcoat,or use of any other type of paint as the primer followedby the use of a standard topcoat.1.4 The values stated in SI units are to be regarded asstandard.No other units of m
6、easurement are included in thisstandard.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
7、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 Trad
8、e Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD823 Practices for Producing Films of Uniform Thicknessof Paint,Coatings and Related Products on Test PanelsD1640 Test Methods for Drying,Curing,or Film Formationof Or
9、ganic CoatingsE177 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 enamel holdout,nthe ability of a primer/topcoatsystem to retain gloss of the topco
10、at relative to gloss of thetopcoat over a non-porous,smooth surface.3.1.2 primer,nan undercoat of paint applied to prepare asurface for final painting.3.1.3 topcoat,na coating,intended as the final coat of afinished system,which has the desired appearance and resis-tance properties as specified by t
11、he end user.4.Summary of Test Method4.1 Asubstrate,preferably a non-porous,smooth drawdowncard,is coated using a test primer and allowed to dry.Theprimer-coated substrate is then coated with the standard top-coat and allowed to dry(primed topcoat).4.2 A non-porous,smooth substrate is coated using on
12、ly thestandard topcoat and allowed to dry(unprimed topcoat).4.3 Gloss measurements are taken over the primed topcoatand also over the unprimed topcoat.The difference in the glossreading between the primed topcoat system and unprimedtopcoat system is an indication of enamel holdout.Smallerdifferences
13、 indicate better enamel holdout.5.Significance and Use5.1 This standard may be used by paint companies and rawmaterial suppliers to assess the interactions of primers and1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is t
14、he direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved April 1,2019.Published April 2019.Originallyapproved in 2012.Last previous edition approved in 2013 as D7786 13.DOI:10.1520/D7786-13R19.2For referenced ASTM standards,visit the ASTM website,www.astm.org
15、,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 stand
16、ard 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 topcoats with respect to their ability to provide good enamelholdout.Primer/topcoat systems with the best enamel holdoutwill result in desirable gloss in the first coat of topcoatapplication.6.Apparatus6.1 Fi