ASTM B680

ASTM B680 – Standard Test Method for Seal Quality of Anodic Coatings on Aluminum by Acid Dissolution

Description:

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.