摘要 |
<p>Aluminum or aluminum alloy is first anodized to form an oxide film thereon. Before being colored electrolytically in an electrolytic solution, the anodized basis metal is made anodic in this solution, and direct current is passed therethrough. The basis metal is then electrolyzed in the same solution by use of alternating current for actual coloring operation. The electrolytic solution in use contains at least two metallic salts, together with or without a strongly reducing compound.</p> |