1、Designation: B 136 84 (Reapproved 2008)e1Endorsed by AmericanElectroplaters SocietyEndorsed by NationalAssociation of Metal FinishersStandard Method forMeasurement of Stain Resistance of Anodic Coatings onAluminum1This standard is issued under the fixed designation B 136; the number immediately foll
2、owing 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 (e) indicates an editorial change since the last revision or reapproval.This standard has been appr
3、oved for use by agencies of the Department of Defense.e1NOTEThe units statement in subsection 1.6 was corrected editorially in April 2008.1. Scope1.1 This method is intended to determine whether anodicoxide coatings on aluminum and its alloys, that have under-gone a sealing treatment and contact wit
4、h an acid solution, arestainproof or nonadsorptive with respect to dyes.1.2 Coatings that have been properly sealed should be proofagainst adsorption of coloring materials and, hence, “nonstain-ing” in many types of service.1.3 This method is applicable to anodic coatings intendedfor applications wh
5、ere they are exposed to the weather, or forprotective purposes in corrosive media, and where resistance tostaining is important.NOTE 1Performance in this test is predictive only of susceptibility tostain by dyes. It is not intended to be predictive of other factors in serviceperformance such as pitt
6、ing or general corrosion.NOTE 2For Aluminum Association Class I and II architectural anodiccoatings that are sealed in solutions containing less than 15 ppm silicatesor 3 ppm phosphates, the acid pretreatment may be omitted.1.4 In the case of coatings colored in deep shades, whereestimation of the i
7、ntensity of any residual dye stain is difficult,interpretation of the test is based on whether or not the originalcolor has been affected by the action of the test.1.5 This method is not applicable to:1.5.1 Chromic acid type anodic coatings.1.5.2 Anodic coatings on aluminum alloys containing moretha
8、n 2 mass % Cu or 4.5 mass % Si.1.5.3 Anodic coatings that have been sealed only in dichro-mate solutions.1.5.4 Anodic coatings that have undergone a treatment torender them hydrophobic.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in this
9、standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to
10、 use.2. Summary of Test Method2.1 The method depends upon the observation that a non-sealed or poorly sealed anodic coating is attacked by acid andeasily colored by dye, while an adequately sealed coating is notappreciably attacked and does not retain any dye stain.2.2 The method comprises contactin
11、g the test area of theanodized specimen with nitric acid solution and, after rinsingand drying, applying a special dye solution followed by rinsingand rubbing the test area with pumice powder, drying, andvisual examination of the test area for retention of dye stain.Coatings that exhibit no dye stai
12、n or change in color areconsidered to have passed the test.3. Reagents3.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemic
13、al Society,2where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.3.2 Nitric Acid SolutionPrepare a 40 6 5 mass % solutionof nitric acid (H
14、NO3) in distilled or deionized water.NOTE 3A convenient way is to carefully add one volume of 70 %HNO3(sp gr 1.41 at 20C) to an equal volume of water, while stirring,1This method is under the jurisdiction ofASTM Committee B08 on Metallic andInorganic Coatings and is the direct responsibility of Subc
15、ommittee B08.07 onConversion Coatings.Current edition approved April 1, 2008. Published April 2008. Originallyapproved in 1940. Last previous edition approved in 2003 as B 136 84 (2003).2Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For sugges
16、tions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.observing the normal precautions for handling strong acids.3.3 Special Dye SolutionDissolve1gofaluminum blue2LW dye3in 50 mL of distilled or deionized water. The pH ofthe dye test solution shall be adjusted to 5.0 6
18、0.5 andmaintained at this value with additions of acetic acid or sodiumhydroxide, as required.NOTE 4Dye solutions contaminated with soluble phosphates havereduced capability for staining nonsealed or poorly sealed anodic coatings.The dye test solution should have less than 20 ppm of phosphorus assol
19、uble PO43-. This corresponds to a phosphorus content of less than 0.05mass % in the dye powder. Under some conditions of storage and use, dyetest solutions may become contaminated or deteriorate with age. To checkthe reliability of a used or aged dye test solution, it should be applied fromtime to t
20、ime to a freshly prepared, nonsealed anodic coating on aluminumto confirm that it will produce a permanent, deeply colored stain in theanodic film.4. Procedure4.1 Perform the test on an area that has not been contami-nated by handling.4.2 Apply a drop of HNO3(40 6 5 mass %) on the test areaand allow
21、 it to remain there for 2 min 6 5 s. The temperatureof the HNO3and of the test specimens shall be 25 6 5C.4.3 Wash the test area thoroughly with running water andblot dry with a clean cloth. The temperature of the water shallbe 25 6 5C.4.4 Apply a drop of the dye solution to the test area andallow i
22、t to remain there for 5 min 6 10 s. The temperature ofthe dye solution and of the test specimen shall be 25 6 5C.4.5 Wash the test area thoroughly with running water, thenrub it with pumice powder (NF or USP Fine Grade)4and aclean cloth wet with water, and finally rinse with water and blotdry with a
23、 clean cloth. The temperature of the water shall be25 6 5C.NOTE 5The pumice scrub removes sealing smut that may absorb thedye. Smut is more difficult to remove after aging than it is from freshlysealed work. Dye that has penetrated the pores of the oxide will not beremoved except by removing the oxi
24、de. On sound oxides, a pumice scrubwill do little more than burnish the surface, even with heavy handpressure.5. Interpretation5.1 The test specimen shall be considered to have passed thetest if no color from the dye is visible in the test area. Anyvisible retention of dye color in the test area is
25、considered afailure.5.2 In the case of anodic coatings colored in deep shades,where visual detection of any residual dye stain is difficult orimpossible, the criterion for passing the test shall be no visiblechange in the color of the coating from the action of the test.NOTE 6For special application
26、s it may be found desirable to make thestaining test using a solution with which the article may come in contactin service. For example, it is sometimes convenient to test anodicallycoated aluminum cafeteria trays with coffee. Composition of test solutionand test conditions should be standardized fo
27、r each application.NOTE 7Sometimes the time interval between sealing and applicationof the stain test influences the result. In such cases, the purchaser andseller should agree upon a time limit for application of this test after thesealing operation.ASTM International takes no position respecting t
28、he validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard
29、is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International H
30、eadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This
31、standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), o
32、r serviceastm.org (e-mail); or through the ASTM website(www.astm.org).3A suitable dye for this test is Aluminum Blue 2LW, available from SandozColors and Chemicals, East Hanover, NJ, 07936.4A suitable material is available as product No. P363 from Fisher Scientific Co.,Fairlawn, NJ, 07410.B 136 84 (2008)e12
