Sealing of anodically oxidized aluminum or aluminum alloy surfaces and compounds useful therefor

摘要

Anodically oxidized aluminium or aluminium alloy surfaces are sealed in the presence of an anti-smut agent which is a colorless, light-fast, organic compound having a molecular weight of at least 350 and containing (i) at least one sulphonic acid group; and (ii) a carboxy group and a hydroxy group both aromatically bound and located ortho- to each other on the same aromatic ring, preferably a benzene ring.