1、Designation:D500799(Reapproved 2017)Standard Test Method forWet-to-Dry Hiding Change1This standard is issued under the fixed designation D5007;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 pare
2、ntheses 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 determination of the changein hiding power of an architectural coating during drying,byvisual evaluation of the wet and dry f
3、ilm.1.2 This test method is not recommended for colors otherthan white and tints.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with
4、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 use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standa
5、rd-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:2D2805 Test Method for Hiding Power of Paints by Ref
6、lec-tometryD3924 Specification for Environment for Conditioning andTesting Paint,Varnish,Lacquer,and Related Materials(Withdrawn 2016)33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 hiding index(hS),nthe Spreading Index at a stan-dard film opacity.3.1.1.1 DiscussionIn this tes
7、t method the latter is a visualcontrast standard prepared by applying a semi-opaque whitecoating on a black and white hiding-power chart to give acontrast ratio of 0.98(98%)which is just short of completehiding,and is the conventional so-called full hiding end pointin photometric hiding-power method
8、s such as Test MethodD2805.Refer to the hiding indices of the wet and dry films ashSWand hSDrespectively.Since this test method is intended to measure hiding-powerdifference rather than hiding power itself,a 0.98(98%)contrast ratio standard is not required.It is necessary only thatthe same standard
9、be used for measuring both wet and dryfilms.See 3.1.8.For this purpose the standard needs to liewithin the contrast range of both the wet and dry stripes,whichis true of the 0.98(98%)contrast-ratio standard for mostcommercial paints.With paints of unusually low hiding,alower contrast standard may be
10、 required,which can be simplyone of the stripes taken from a drawdown of the test paint.3.1.2 hiding power,nthe spreading rate of a paint applieduniformly on a standard black and white hiding power chart togive a standard degree of contrast just short of complete hiding.3.1.2.1 DiscussionIn reflecto
11、metry the standard contrastfor hiding power measurements is generally accepted as thecontrast ratio C=0.98(98%),which with white and lighttinted coatings is equivalent to a visual color difference ofabout 0.75 CIELAB units.That amount of color difference canreasonably be described as“just-short-of c
12、omplete-hiding.”Since this is a visual method it employs a visual comparator asa standard,which is a hiding power chart with a white coatingapplied at a contrast ratio of 0.98(98%).3.1.3 logicator,na multi-notch applicator with clearances,and corresponding wet film thicknesses and spreading rates,in
13、equal percentage steps.3.1.4 logicator scale,na scale with values directly relatedto the logarithms of corresponding spreading rates.3.1.4.1 DiscussionA specified change in scale value rep-resents the same percentage change in spreading rate over anypart of such a scale.3.1.5 spreading index(h),nthe
14、 spreading rate expressedin logicator scale units(LU)as described in 3.1.4 and 3.1.7.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural Coatings.Current edit
15、ion approved June 1,2017.Published June 2017.Originallyapproved in 1989.Last previous edition approved in 2013 as D5007 99(2013).DOI:10.1520/D5007-99R17.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStanda
16、rds 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.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 Reco
