1、Designation:D778613Standard 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 parentheses indicat
2、es 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 determine the abso
3、rptioncharacteristics 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-poroussmooth surface.1.2 The standard is written in the context that the user willbe evaluating the enamel holdout chara
4、cteristics 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 paintsother than primers as
5、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 measurement are inc
6、luded 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 and health practices and determine the applica-bility of regulatory limitations prior to
7、use.2.Referenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test PanelsD1640 Test Methods for Drying,Curing,or Film Formationof Organic Coatings at Room TemperatureE177 Practice for U
8、se 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 topcoat relative to gloss of thetopcoa
9、t 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 the end user.4.Summary of Test Met
10、hod4.1 A substrate,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 only thestandard topcoat and allow
11、ed 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 indicate better enamel holdout.
12、5.Significance and Use5.1 This standard may be used by paint companies and rawmaterial suppliers to assess the interactions of primers andtopcoats with respect to their ability to provide good enamelholdout.Primer/topcoat systems with the best enamel holdoutwill result in desirable gloss in the firs
13、t coat of topcoatapplication.6.Apparatus6.1 Film Applicator,preferably a drawdown bar,capable ofapplying wet-film thickness of approximately 0.075 mm(3.0mils).1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct r
14、esponsibility ofSubcommittee D01.42 on Architectural Coatings.Current edition approved Nov.1,2013.Published December 2013.Originallyapproved in 2012.Last previous edition approved in 2012 as D7786 12.DOI:10.1520/D7786-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact AS
15、TM 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 States1 6.2 If preferred,brush,roller or sp
16、ray applicators can besubstituted for the drawdown applicators.6.3 Gloss Meter capable of measuring 20 and 60gloss.7.Reagents and Materials7.1 Substrate Desired for TestingThe preferred substrateshould have a uniform flat surface to enable paint films to beapplied with the preferred drawdown bar applicator.Unlessotherwise agreed upon,a non-porous smooth drawdown card isused.Other commonly used substrates include:gypsum panel,wood or drawdown cards with non-porous and porous sections.The choice t
