ASTM_B_680_-_80_2014.pdf

Designation:B68080(Reapproved 2014)Standard Test Method forSeal Quality of Anodic Coatings on Aluminum by AcidDissolution1This standard is issued under the fixed designation B680;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 test method covers a test for the quality of seal ofporous anodic coatings on aluminum and its alloys.It is basedupon the loss in mass of the coating after immersion in a warmphosphoric-chromic acid solution.1.2 This test method is applicable to anodic coatings in-tended for exposure to the weather,or for protective purposesin corrosive media,and where resistance to staining is impor-tant.1.3 This test method is not applicable to:1.3.1 Hard coatings,which normally are not sealed.1.3.2 Anodic coatings that have been sealed only in dichro-mate solutions.1.3.3 Anodic coatings that have undergone a treatment torender them hydrophobic.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2B137 Test Method for Measurement of Coating Mass PerUnit Area on Anodically Coated AluminumD1193 Specification for Reagent Water3.Significance and Use3.1 This test method describes a destructive test procedurefor measuring the degree of seal of the porosity in anodic oxidecoatings.Low coating mass loss is an indication of good sealquality and of the ability of the coating to resist staining and“blooming”in many types of service.3.2 This test method is suitable for quality control purposeswithin manufacturing operations and for determining whetheranodized parts meet seal quality requirements in applicablespecifications.4.Apparatus4.1 Laboratory Balance,accurate to 1 mg.4.2 Glass Container,means of heating and stirring,and athermometer.There shall be no metal in contact with the testspecimen or the solution.5.Acid Test Solution5.1 The test solution shall have the following makeup:Chromic acid anhydride(CrO3)20 0.5 gOrthophosphoric acid of 85 mass%,density 1.6935 0.5 mLDistilled or deionized water conforming with Type IIIReagent Water of Specification D1193,to makeup to1000 mLNOTE1This solution is commonly referred to as a“strippingsolution”for anodic coatings and is of the same composition as thatemployed in Test Method B137.This solution dissolves the anodic coatingwith no significant attack of the substrate metal.5.2 The test solution may be used repeatedly but shall bediscarded after 1 g of anodic coating has been dissolved perlitre of solution.NOTE2The solution may be used for as many as 20 test specimensper litre provided that the average mass loss does not exceed 50 mg perspecimen.6.Preparation of Test Specimen6.1 Select an uncontaminated specimen having an areaabout 1 dm2of the anodized surface to be tested.6.2 The mass of the specimen shall not exceed 200 g.6.3 When it is desired to conduct the test on one face onlyof the specimen,the anodic coating on the other surface is1This test method is under the jurisdiction ofASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 onConversion Coatings.Current edition approved Nov.1,2014.Published November 2014.Originallyapproved in 1980.Last previous edition approved in 2009 as B680 80(2009).DOI:10.1520/B0680-80R14.2For 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 removed by a chemical or mechanical process,leaving thesignificant face intact.6.4 Bare,cut edges and other uncoated surfaces of thespecimen shall be left bare and shall not be given a protectivecoating.7.Procedure7.1 Measure the area(A)in square decimetres of the coatingwithout including cut edges or other uncoated surfaces.7.2 Weigh the specimen to the nearest 1 mg(W1).7.3 Immerse the specimen for 15 6 0.1 min in the stirredacid test solution maintained at a temperature of 38 6 1C.7.4 Remove the specimen and wash thoroughly in deionizedor distilled water conforming with Type III reagent water ofSpecification D1193.7.5 Dry the specimen with clean compressed air,or allow itto air-dry.7.6 Reweigh the specimen to the nearest 1 mg(W2).7.7 When it is desired to express the mass loss in the test asa percent of the total c