Alcan International Limited

Dan Fern

Harry Sang

Lorne D Kenny

Prasad S Apte

Jose L Gazapo

Bryn Chamberlain

A process for coloring a metal surface and colored metal products thus produced. The process involves forming a layer of a metal oxide on a surface of the metal to be colored and then bringing about permanent plastic deformation of the surface. If the oxide layer is of a suitable thickness (e.g. 500.ANG.-1 .mu.m) and the deformation is sufficiently high (preferably producing a reduction in thickness of the metal article by 30% or more), the resulting metal article exhibits an attractive color (usually a dichroic pastel color). The article can then be fabricated into finished articles, e.g. beverage cans, in the usual way.

Process for coloring metal surfaces

Aluminum articles having porous anodic oxide films are given an exposure-resistant blue coloration by dipping them first in an aqueous solution of a phosphomolybdic acid or a silicomolybdic acid, and then in a solution of a strong reducing agent such as a stannous salt, and finally sealing the porous oxide film. The method is suitable for batch or continuous operation and useful to color bumpers for passenger cars.

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Dan Fern