Patent ID: 6905775

Claim:
An aluminium workpiece comprising on a surface thereof: an oxide film that is formed anodically, which film is 10 to 200 nm thick; and a coating on the oxide film, which coating consists essentially of at least one adhesion promoter containing one or more of Cr, Mn, Mo, Si, Ti, Zr and F, optionally containing an organic polymer, wherein the Cr, Mn, Mo, Si, Ti, Zr and F are present in inorganic form, and wherein the adhesion promoter is applied as a no-rinse coating, which is a composition consisting essentially of the adhesion promoter in a volatile vehicle which evaporates leaving a film of the adhesion promoter, or a conversion coating, which reacts chemically with the oxide film to form a film of the adhesion promoter, said workpiece being an aluminium sheet of which at least one surface has the oxide film, the adhesion promoter and a paint layer or an adhesive overlying the adhesion promoter.