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), “Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution,” provides a recognized procedure for evaluating the seal quality of porous anodic coatings on aluminum and its alloys. Developed by ASTM International, this standard uses a controlled acid dissolution test to measure the loss in mass experienced by an anodic coating, which directly correlates to the resistance against staining and corrosion. This method is particularly important for applications where the durability and longevity of anodized aluminum are essential.

Key Topics

• Seal Quality Assessment: The test method focuses on determining the degree to which the pores in an anodic oxide coating have been sealed. Proper sealing enhances corrosion resistance and reduces susceptibility to staining and “blooming.”
• Destructive Testing: As a destructive test, this method involves measuring the mass loss of the anodic coating after immersion in a warm phosphoric-chromic acid solution.
• Suitability: Intended for anodic coatings exposed to weather or corrosive environments and where stain resistance is crucial. It is not suitable for hard coatings, coatings sealed only in dichromate solutions, or hydrophobic-treated coatings.
• Measurement Units: The procedure is standardized using SI units, ensuring international compatibility and consistency.

Applications

This standard test method is widely used in various industries for:

• Quality Control in Manufacturing: Provides a reliable quality assurance method to verify that anodized aluminum parts meet specified seal quality requirements during production.
• Specification Compliance: Ensures that aluminum components used in architectural, automotive, aerospace, and marine industries adhere to client and industry specifications for corrosion resistance.
• Product Performance Evaluation: By quantifying the coating’s ability to resist mass loss, the method helps manufacturers predict and enhance performance in end-use environments.
• Research and Development: Used in R&D to compare the effectiveness of different sealing processes and to optimize anodizing procedures for better long-term protection.

Related Standards

For comprehensive assessment of anodic coatings and related processes, the following standards are often referenced alongside ASTM B680-80(2019):

• ASTM B137 – Test Method for Measurement of Coating Mass Per Unit Area on Anodically Coated Aluminum: Used for determining the total mass of anodic coatings, including procedures similar to the acid dissolution technique.
• ASTM D1193 – Specification for Reagent Water: Specifies the water quality to be used during testing, ensuring consistent and reliable results.

Practical Value

Adopting ASTM B680-80(2019) enhances consistency in evaluating anodic coating quality, reduces product failure risks, and supports compliance with international requirements. For manufacturers and quality assurance professionals, this standard method provides:

• Reliable, quantifiable results for seal quality
• Improved durability and aesthetics in anodized aluminum products
• Confidence in meeting customer and regulatory expectations for corrosion resistance

Using this standard is key to ensuring the longevity and performance of anodized aluminum components in demanding service conditions, supporting quality assurance programs across critical industry sectors.

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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