ASTM B680-80(2019)

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

SIGNIFICANCE AND USE
3.1 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.  
3.2 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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2019
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.07 - Conversion Coatings

Relations

• Replaces: ASTM B680-80(2014) - Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution
• Effective Date: 01-Oct-2019
• Refers: ASTM B137-95(2009) - Standard Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum
• Effective Date: 15-Apr-2009
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM B137-95(2004) - Standard Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum
• Effective Date: 01-Oct-2004
• Refers: ASTM B137-95(2000) - Standard Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum
• Effective Date: 10-Mar-2000
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999

Overview

ASTM B680-80(2019), titled Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution, is an internationally recognized ASTM standard. It specifies a method to assess the quality of the seal on anodic oxide coatings applied to aluminum and aluminum alloys. The core of this test is to measure the loss in mass of the coating after immersion in a warm phosphoric-chromic acid solution. A lower mass loss indicates a higher degree of sealing, meaning increased resistance to staining, corrosion, and surface "blooming" in service.

Primarily a destructive test method, ASTM B680-80(2019) is widely used in quality control within manufacturing settings to verify whether anodized aluminum parts meet required seal quality specifications.

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Key Topics

• Seal Quality Measurement:
  Evaluates the effectiveness of sealing in closing pore structures of anodic coatings on aluminum.

• Test Procedure:

  • Immersion of the specimen in a phosphoric-chromic acid solution at controlled temperature and time.
  • Measurement of the specimen’s mass loss per area to assess seal integrity.

• Applicability:

  • Suitable for anodic coatings intended for outdoor exposure or use in corrosive environments.
  • Relevant for parts where stain resistance is crucial.

• Limitations:

  • Not applicable to:
    • Hard anodic coatings (usually unsealed)
    • Coatings sealed only in dichromate solutions
    • Coatings treated to be hydrophobic

• Standard Units:
  The test method and results use SI units exclusively.

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Applications

ASTM B680-80(2019) has broad utility in industrial and commercial settings, with a focus on quality assurance, product validation, and process control. Its main uses include:

• Quality Control in Anodizing Operations:
  Provides a reliable benchmark to ensure sealing processes are effective and consistent for mass-produced anodized aluminum products.

• Specification Compliance Testing:
  Determines whether anodized components meet the required standard specifications for seal quality, particularly for products subject to harsh environmental conditions.

• Corrosion and Stain Resistance Assurance:
  Vital for applications in the architectural, automotive, marine, and electronics sectors where anodized aluminum is exposed to weathering or corrosive agents.

• Research and Development:
  Assists manufacturers and laboratories in refining anodizing and sealing processes for improved product durability and performance.

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Related Standards

To ensure comprehensive and consistent testing, ASTM B680-80(2019) cites other related ASTM standards, including:

• ASTM B137:
  Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum
• ASTM D1193:
  Specification for Reagent Water (specifies the water quality for test solutions)

Other relevant standards:

• Standards governing the anodizing of aluminum and aluminum alloys
• International guidelines, such as those established by the World Trade Organization TBT Committee, for the development of testing standards

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By following ASTM B680-80(2019), organizations can ensure their anodized aluminum products attain consistent seal quality, enhancing performance, longevity, and customer satisfaction, especially in demanding applications. Moreover, compliance with internationally accepted standards like ASTM B680 supports global competitiveness and regulatory alignment.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B680 − 80 (Reapproved 2019)
Standard Test Method for
Seal Quality of Anodic Coatings on Aluminum by Acid
Dissolution
This standard is issued under the fixed designation B680; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers a test for the quality of seal of
B137 Test Method for Measurement of Coating Mass Per
porous anodic coatings on aluminum and its alloys. It is based
Unit Area on Anodically Coated Aluminum
upon the loss in mass of the coating after immersion in a warm
D1193 Specification for Reagent Water
phosphoric-chromic acid solution.
1.2 This test method is applicable to anodic coatings in-
3. Significance and Use
tended for exposure to the weather, or for protective purposes
3.1 This test method describes a destructive test procedure
in corrosive media, and where resistance to staining is impor-
for measuring the degree of seal of the porosity in anodic oxide
tant.
coatings. Low coating mass loss is an indication of good seal
quality and of the ability of the coating to resist staining and
1.3 This test method is not applicable to:
“blooming” in many types of service.
1.3.1 Hard coatings, which normally are not sealed.
3.2 This test method is suitable for quality control purposes
1.3.2 Anodic coatings that have been sealed only in dichro-
within manufacturing operations and for determining whether
mate solutions.
anodized parts meet seal quality requirements in applicable
1.3.3 Anodic coatings that have undergone a treatment to
specifications.
render them hydrophobic.
4. Apparatus
1.4 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4.1 Laboratory Balance, accurate to 1 mg.
standard.
4.2 Glass Container, means of heating and stirring, and a
1.5 This standard does not purport to address all of the
thermometer. There shall be no metal in contact with the test
safety concerns, if any, associated with its use. It is the
specimen or the solution.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 5. Acid Test Solution
mine the applicability of regulatory limitations prior to use.
5.1 The test solution shall have the following makeup:
1.6 This international standard was developed in accor-
Chromic acid anhydride (CrO ) 20±0.5g
dance with internationally recognized principles on standard-
Orthophosphoric acid of 85 mass %, density 1.69 35 ± 0.5 mL
Distilled or deionized water conforming with Type III 1000 mL
ization established in the Decision on Principles for the
Reagent Water of Specification D1193, to make
Development of International Standards, Guides and Recom-
up to
mendations issued by the World Trade Organization Technical
NOTE 1—This solution is commonly referred to as a “stripping
Barriers to Trade (TBT) Committee.
solution” for anodic coatings and is of the same composition as that
employedinTestMethodB137.Thissolutiondissolvestheanodiccoating
with no significant attack of the substrate metal.
5.2 The test solution may be used repeatedly but shall be
discarded after1gof anodic coating has been dissolved per
litre of solution.
This test method is under the jurisdiction ofASTM Committee B08 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 on
Conversion Coatings. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2019. Published October 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual
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