COLORING METHOD OF ALUMINUM OR ALUMINUM ALLOY

PURPOSE:To accomplish uniform coloring with good throwing power by using an Ni salt with a simple operation in an electrolytic coloring method, by subjecting A or an A alloy to an electrolytic treatment by using an aq. soln. contg. Ni ions and coloring assistants and dipping the same in an aq. soln. contg. metallic ions and a reducing agent. CONSTITUTION:Anodized Al or Al alloy is subjected to an AC electrolytic treatment in an aq. soln. contg. Ni ions and coloring assistants. The coloring, assistants are >=1 kinds among a boric acid, hypophosphoric acid, thiosulfuric acid, carboxylic acid, ammonium salts of these acids and saccharides. The Al material subjected to such treatment is washed according to need and is dipped in an aq. soln. B differing from the soln. A. The soln. B contains metal, for example, Co ions, and a reducing agent, for example, hypophosphite, formalin, etc. The coloring to a black or bronze color tone is accomplished with good throwing power in a relatively short time and small power consumption according to the above-mentioned method.