Coated aluminium workpiece

Coating comprising adhesion promoter(s) excluding silane is applied to an aluminium work piece with an anodic oxide film surface. Preferred Features: The work piece is an aluminium sheet, and has a paint, lacquer, varnish or enamel layer over the adhesion promoter layer. An aluminium workpiece comprises, on one of its surfaces, an anodic oxide film and a coating on the film which consists essentially of at least one adhesion promoter containing a polyvinyl phenol, polyacrylic acid or a salt or ester thereof, or polyacrylic acid/zirconia mixture. There may be a paint, lacquer, varnish or enamel layer overlying the adhesion promoter coating. Also disclosed is a method for treating an aluminium workpiece comprising precleaning, anodising and applying the adhesion promoter coating. Applications of the aluminium workpieces according to the invention include primed sheets for automotive use, painted sheets for architectural use and lacquered sheets for metal packaging.