ASTM_D_4414_-_95_2013.pdf

Designation:D441495(Reapproved 2013)Standard Practice forMeasurement of Wet Film Thickness by Notch Gages1This standard is issued under the fixed designation D4414;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 practice describes the use of thin rigid metalnotched gages,also called step or comb gages,in the measure-ment of wet film thickness of organic coatings,such as paint,varnish,and lacquer.1.2 Notched gage measurements are neither accurate norsensitive,but they are useful in determining approximate wetfilm thickness of coatings on articles where size(s)and shape(s)prohibit the use of the more precise methods given in TestMethods D1212.1.3 This practice is divided into the following two proce-dures:1.3.1 Procedure AA square or rectangular rigid metalgage with notched sides is used to measure wet film thick-nesses ranging from 3 to 2000 m(0.5 to 80 mils 1).Such agage is applicable to coatings on flat substrates and to coatingson articles of various sizes and complex shapes where it ispossible to get the end tabs of the gage to rest in the same planeon the substrate.1.3.2 Procedure BAcircular thin rigid metal notched gageis used to measure wet film thicknesses ranging from 25 to2500 m(1 to 100 mils).Such a gage is applicable to coatingson flat substrates and to coatings on objects of various sizes andcomplex shapes.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1212 Test Methods for Measurement of Wet Film Thick-ness of Organic Coatings3.Summary of Practice3.1 The material is applied to the articles to be coated andthe wet film thickness measured with a notched gage.3.2 Procedure AA square or rectangular thin rigid metalgage with notched sides,having tabs of varying lengths,ispushed perpendicularly into the film.After removal from thefilm,the gage is examined and the film thickness is determinedto lie between the clearance of the shortest tab wet by the filmand the clearance of the next shorter tab not wetted by the film.3.3 Procedure BA circular thin rigid metal gage havingspaced notches of varying depths around its periphery is rolledperpendicularly across the film.After removal from the film,the gage is examined and the film thickness is determined asbeing between the clearance of the deepest face wetted and theclearance of the next deepest notch face not wetted by the film.4.Significance and Use4.1 Wet film thickness measurements of coatings applied onarticles can be very helpful in controlling the thickness of thefinal dry coating,although in some specifications the wet filmthickness is specified.Most protective and high performancecoatings are applied to meet a requirement or specification fordry film thickness for each coat or for the completed coatingsystem,or for both.4.2 There is a direct relationship between dry film thicknessand wet film thickness.The wet film/dry film ratio is deter-mined by the volume of volatiles in the coating as applied,including permitted thinning.With some flat coatings the dryfilm thickness is higher than that calculated from the wet filmthickness.Consequently,the results from the notch gage arenot to be used to verify the nonvolatile content of a coating.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved July 1,2013.Published July 2013.Originally approvedin 1984.Last previous edition approved in 2007 as D4414 95(2007).DOI:10.1520/D4414-95R13.2For 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 States1 4.3 Measurement of wet film thickness at the time ofapplication is most appropriate as it permits correction andadjustment of the film by the applicator at the time ofapplication.Correction of the film after it has dried orchemically cured requires costly extra labor time,may lead tocontamination of the film,and may introduce problems ofadhesion and integrity of the coating system.4.4 The procedures using notched gages do not provide asaccurate or sens