Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution

SIGNIFICANCE AND USE
This test method describes a destructive test procedure for measuring the degree of seal of the porosity in anodic oxide coatings. Low coating mass loss is an indication of good seal quality and of the ability of the coating to resist staining and “blooming” in many types of service.
This test method is suitable for quality control purposes within manufacturing operations and for determining whether anodized parts meet seal quality requirements in applicable specifications.
SCOPE
1.1 This test method covers a test for the quality of seal of porous anodic coatings on aluminum and its alloys. It is based upon the loss in mass of the coating after immersion in a warm phosphoric-chromic acid solution.
1.2 This test method is applicable to anodic coatings intended for exposure to the weather, or for protective purposes in corrosive media, and where resistance to staining is important.
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 dichromate solutions.
1.3.3 Anodic coatings that have undergone a treatment to render them hydrophobic.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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Publication Date
30-Sep-2004
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ASTM B680-80(2004) - Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B680–80(Reapproved 2004)
Standard Test Method for
Seal Quality of Anodic Coatings on Aluminum by Acid
Dissolution
This standard is issued under the fixed designation B 680; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
1.1 This test method covers a test for the quality of seal of 3.1 This test method describes a destructive test procedure
porous anodic coatings on aluminum and its alloys. It is based formeasuringthedegreeofsealoftheporosityinanodicoxide
upon the loss in mass of the coating after immersion in a warm coatings. Low coating mass loss is an indication of good seal
phosphoric-chromic acid solution. quality and of the ability of the coating to resist staining and
1.2 This test method is applicable to anodic coatings in- “blooming” in many types of service.
tended for exposure to the weather, or for protective purposes 3.2 This test method is suitable for quality control purposes
in corrosive media, and where resistance to staining is impor- within manufacturing operations and for determining whether
tant. anodized parts meet seal quality requirements in applicable
1.3 This test method is not applicable to: specifications.
1.3.1 Hard coatings, which normally are not sealed.
4. Apparatus
1.3.2 Anodic coatings that have been sealed only in dichro-
4.1 Laboratory Balance, accurate to 1 mg.
mate solutions.
1.3.3 Anodic coatings that have undergone a treatment to 4.2 Glass Container, means of heating and stirring, and a
thermometer. There shall be no metal in contact with the test
render them hydrophobic.
1.4 This standard does not purport to address all of the specimen or the solution.
safety concerns, if any, associated with its use. It is the
5. Acid Test Solution
responsibility of the user of this standard to establish appro-
5.1 The test solution shall have the following makeup:
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Chromic acid anhydride (CrO)20 6 0.5 g
Orthophosphoric acid of 85 mass %, density 1.69 35 6 0.5 mL
Distilled or deionized water conforming with Type III 1000 mL
2. Referenced Documents
Reagent Water of Specification D 1193, to make
2.1 ASTM Standards: up to
B 137 Test Method for Measurement of Coating Mass Per
NOTE 1—This solution is commonly referred to as a “stripping solu-
Unit Area on Anodically Coated Aluminum
tion” for anodic coatings and is of the same composition as that employed
D 1193 Specification for Reagent Water
in Test Method B 137. This solution dissolves the anodic coating with no
significant attack of the substrate metal.
2.2 International Standard:
ISO 3210 Anodizing of Aluminum and Its Alloys—
5.2 The test solution may be used repeatedly but shall be
Assessment of Sealing Quality by Measurement of the
discarded after1gof anodic coating has been dissolved per
Loss of Mass After Immersion in Phosphoric-Chromic
litre of solution.
Acid Solution
NOTE 2—The solution may be used for as many as 20 test specimens
per litre provided that the average mass loss does not exceed 50 mg per
specimen.
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 on
6. Preparation of Test Specimen
Chromate Conversion Coatings.
Current edition approved Oct. 1, 2004. Published October 2004. Originally
6.1 Select an uncontaminated specimen having an area
approved in 1980. Last previous edition approved in 2000 as B 680 – 80 (
...

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