Method and composition for forming a coloured coating on a metallic surface

摘要

The invention concerns a method for forming a coloured coating on a metallic surface by contacting the surface of a metallic coil or of a metallic part with an aqueous acidic composition on the base of a source of titanium and at least one complex fluoride and of at least one modified tannin compound, of at least one other polyphenolic compound, of at least one reaction product of these e.g. with titanium or any combination thereof, whereby a coating is generated with the aqueous acidic composition having a well visible intensive colour.