BS EN 12373-4:1998

Aluminium and aluminium alloys. Anodizing. Estimation of loss of absorptive power of anodic oxidation coatings after sealing by dye spot test with prior acid treatment | Status: Superseded, Withdrawn

1 Scope This Part of this European Standard specifies a method of estimating the loss of absorptive power of anodic oxidation coatings that have undergone a sealing treatment, by dye absorption after acid pretreatment. The method is suitable for use as a production control method and is applicable to anodic oxidation coatings which may be subjected to weathering or aggressive environments or where resistance to staining is important. The method is not applicable to those coatings:

1. a) formed on alloys containing more than 2 % copper or 4 % silicon;
2. b) sealed by the dichromate process;
3. c) that have been given supplementary processing, for example oiling, waxing or lacquering;
4. d) that are coloured in deep shades;
5. e) that are less than 3 µm thick.

The method is less appropriate where nickel or cobalt salts, or organic additives, have been added to the sealing bath.