ASTM_D_4752_-_10_2015.pdf

Designation:D475210(Reapproved 2015)Standard Practice forMeasuring MEK Resistance of Ethyl Silicate(Inorganic)Zinc-Rich Primers by Solvent Rub1This standard is issued under the fixed designation D4752;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 a solvent rub technique forassessing the MEK resistance of ethyl silicate(inorganic)zinc-rich primers.The MEK resistance of some two-component ethyl silicate zinc-rich primers has been shown tocorrelate well with the cure of the primer as determined bydiffuse reflectance infrared spectroscopy.2The technique canbe used in the laboratory,field,or in the fabricating shop.Practice D5402 is the preferred method for organic coatings.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 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.Specific hazardstatements are given in Section 6.Consult suppliers MaterialSafety Data Sheet(s)for specific hazard information relating tothe solvent used.2.Referenced Documents2.1 ASTM Standards:3D740 Specification for Methyl Ethyl KetoneD4138 Practices for Measurement of Dry Film Thickness ofProtective Coating Systems by Destructive,Cross-Sectioning MeansD5402 Practice for Assessing the Solvent Resistance ofOrganic Coatings Using Solvent RubsD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic,Nonconductive Coat-ings Applied to Non-Ferrous Metals3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 double rub,nthe act of rubbing a solvent saturatedcloth in one complete forward and backward motion over acoated surface.4.Significance and Use4.1 Ethyl silicate zinc-rich primers cure by the reaction ofthe vehicle with moisture,thereby providing a binder.Asrelative humidity and temperature vary during the day,so doesthe rate of cure.Acertain minimum degree of cure is necessaryprior to topcoating.It has been shown that the degree of cureof ethyl silicate zinc-rich primers can be measured by thechemical changes occurring using diffuse reflectance infraredspectroscopy.2This solvent rub test has been shown to corre-late well with the infrared spectroscopic results of sometwo-component ethyl silicate inorganic zinc systems.4.2 The cure rating required for the application of specifictopcoats must be agreed upon before the practice is used.5.Reagents and Materials5.1 Methyl Ethyl Ketone(MEK),in accordance with Speci-fication D740.5.2 100%Cotton,Shop Cloth,approximately 300 by 300mm(12 by 12 in.)contrasting in color to the coating to beevaluated.5.3 Squeeze Bottle.5.4 Proper Safety Equipment,as determined from the sol-vent MSDS,for example,solvent resistant gloves,respirator.6.Procedure6.1 Select areas on the primer surface at least 150 mm(6 in.)long on which to run the tests.Clean the surface with tap wateror dry cloth to remove loose material.NOTE1Tap water may influence the cure of the zinc-rich primer.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved Feb.1,2015.Published February 2015.Originallyapproved in 1987.Last previous edition approved in 2010 as D4752 10.DOI:10.1520/D4752-10R15.2Starr,T.L.,Henton,L.E.,Lewis,W.S.,and Rideout,F.A.,“Improved FieldReliability of High Performance Coating Systems:Phase IIDevelop Proceduresand Criteria in Critical Performance Areas,”available from SSPC:The Society forProtective Coatings,40 24th St.,Sixth Floor,Pittsburgh,PA 15213,www.sspc.org.3For 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 6.2 Measure the dry film thickness of the primer in theselected areas in accordance with Test Methods D7091 orD4138.Mark a 150-by 25-mm(6-by 1-in.)rectangular testarea on the undamaged cleaned surface using a pencil or othersuitable solvent resistant marker.6.3 Fold the cloth into a pad of double thickness andsaturate it to a dripping wet condition with the methyl ethylketone.Do not allow more than 10 s to elapse beforeproceeding to the next steps.6.4 Place the properly protected index finger