ASTM B136-84(2008)e1
(Test Method)Standard Method for Measurement of Stain Resistance of Anodic Coatings on Aluminum
Standard Method for Measurement of Stain Resistance of Anodic Coatings on Aluminum
ABSTRACT
This specification covers measurement of strain resistance of anodic coatings on aluminium and its alloys, that have undergone a sealing treatment and contact with an acidic solution, are stainproof or nonadsorptive with respect to dyes. The method comprises contacting the test area of the anodized specimen with nitric acid solution and, after rinsing and drying, applying a special dye solution followed by rinsing and rubbing the test area with pumice powder, drying, and visual examination of the test area for retention of dye stain. Coatings that exhibit no dye stain or change in color are considered to have passed the test. Reagent grade chemicals shall be used in all tests. A specified solution of nitric acid shall be prepared in distilled or deionized water. A specified volume of aluminium blue 2WL dye shall be dissolved in distilled or deionized water.
SCOPE
1.1 This method is intended to determine whether anodic oxide coatings on aluminum and its alloys, that have undergone a sealing treatment and contact with an acid solution, are stainproof or nonadsorptive with respect to dyes.
1.2 Coatings that have been properly sealed should be proof against adsorption of coloring materials and, hence, “nonstaining” in many types of service.
1.3 This method is applicable to anodic coatings intended for applications where they are exposed to the weather, or for protective purposes in corrosive media, and where resistance to staining is important.
Note 1—Performance in this test is predictive only of susceptibility to stain by dyes. It is not intended to be predictive of other factors in service performance such as pitting or general corrosion.
Note 2—For Aluminum Association Class I and II architectural anodic coatings that are sealed in solutions containing less than 15 ppm silicates or 3 ppm phosphates, the acid pretreatment may be omitted.
1.4 In the case of coatings colored in deep shades, where estimation of the intensity of any residual dye stain is difficult, interpretation of the test is based on whether or not the original color 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 more than 2 mass % Cu or 4.5 mass % Si.
1.5.3 Anodic coatings that have been sealed only in dichromate solutions.
1.5.4 Anodic coatings that have undergone a treatment to render them hydrophobic.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: B136 − 84 (Reapproved 2008) Endorsedby American
Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Method for
Measurement of Stain Resistance of Anodic Coatings on
Aluminum
This standard is issued under the fixed designation B136; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—The units statement in subsection 1.6 was corrected editorially in April 2008.
1. Scope 1.6 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This method is intended to determine whether anodic
standard.
oxide coatings on aluminum and its alloys, that have under-
gone a sealing treatment and contact with an acid solution, are
1.7 This standard does not purport to address all of the
stainproof or nonadsorptive with respect to dyes. safety concerns, if any, associated with its use. It is the
responsibility of whoever uses this standard to consult and
1.2 Coatings that have been properly sealed should be proof
establish appropriate safety and health practices and deter-
against adsorption of coloring materials and, hence, “nonstain-
mine the applicability of regulatory limitations prior to use.
ing” in many types of service.
1.3 This method is applicable to anodic coatings intended
2. Summary of Test Method
for applications where they are exposed to the weather, or for
2.1 The method depends upon the observation that a non-
protectivepurposesincorrosivemedia,andwhereresistanceto
sealed or poorly sealed anodic coating is attacked by acid and
staining is important.
easilycoloredbydye,whileanadequatelysealedcoatingisnot
NOTE 1—Performance in this test is predictive only of susceptibility to
appreciably attacked and does not retain any dye stain.
stain by dyes. It is not intended to be predictive of other factors in service
performance such as pitting or general corrosion. 2.2 The method comprises contacting the test area of the
NOTE 2—ForAluminumAssociation Class I and II architectural anodic
anodized specimen with nitric acid solution and, after rinsing
coatings that are sealed in solutions containing less than 15 ppm silicates
and drying, applying a special dye solution followed by rinsing
or 3 ppm phosphates, the acid pretreatment may be omitted.
and rubbing the test area with pumice powder, drying, and
1.4 In the case of coatings colored in deep shades, where
visual examination of the test area for retention of dye stain.
estimation of the intensity of any residual dye stain is difficult,
Coatings that exhibit no dye stain or change in color are
interpretation of the test is based on whether or not the original
considered to have passed the test.
color has been affected by the action of the test.
1.5 This method is not applicable to: 3. Reagents
1.5.1 Chromic acid type anodic coatings.
3.1 Purity of Reagents—Reagent grade chemicals shall be
1.5.2 Anodic coatings on aluminum alloys containing more
used in all tests. Unless otherwise indicated, it is intended that
than 2 mass % Cu or 4.5 mass % Si.
all reagents shall conform to the specifications of the Commit-
1.5.3 Anodic coatings that have been sealed only in dichro- 2
tee onAnalytical Reagents of theAmerican Chemical Society,
mate solutions.
where such specifications are available. Other grades may be
1.5.4 Anodic coatings that have undergone a treatment to
used, provided it is first ascertained that the reagent is of
render them hydrophobic.
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ThismethodisunderthejurisdictionofASTMCommitteeB08onMetallicand Reagent Chemicals, American Chemical Society Specifications, American
Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 on Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Conversion Coatings. listed by the American Chemical Society, see Analar Standards for Laboratory
Current edition approved April 1, 2008. Published April 2008. Originally Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
approved in 1940. Last previous edition approved in 2003 as B136 – 84 (2003). and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
DOI: 10.1520/B0136-84R08E01. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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B136 − 84 (Reapproved 2008)
sufficiently high purity to permit its use without lessening the 4.4 Apply a drop of the dye solution to the test area and
accuracy of the determination. allow it to remain there for
...
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