JP2588036B

PURPOSE:To stably form a patina film excellent in adhesion and uniform in color tone on the surface of a base material in a short time by forming a thin film of copper or a copper alloy on the base material surface and then treating the thin film with a chemical conversion coating soln. added with an oxidizing agent. CONSTITUTION:The surface of a base material on which patina is to be formed is preferably roughened, and then a thin film of copper or a copper alloy is formed on the surface. The thin film is preferably formed by thermal spraying, and its thickness is appropriately controlled to about 1-100mum or preferably to about 5-40mum. The surface roughness of this thin film is adjusted to about 3-50mum or preferably to about 5-40mum. The thin film is treated with a chemical conversion coating soln. mixed with >= about 3wt.% of an oxidizing agent such as MnO2. Consequently, the patina having a uniform and deep color tone is formed on the surface of the base material regardless of its kind with good adhesion in a short time.