ELECTROLYTIC COLORING METHOD OF ALUMINUM MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide an electric coloring method of an aluminum material by which not only coloring unevenness generated within an energizing lot of one time but also coloring unevenness generated between respective energizing lots are prevented as less as possible and the aluminum material colored to an uniform color tone can be industrially and stably manufactured at the time of AC electrolytic coloring treatment of the aluminum material. SOLUTION: In the electrolytic coloring method of the aluminum material, the aluminum material made of aluminum of an aluminum alloy subjected to an anodic oxidation film treatment is immersed in an electrolytic coloring treating bath containing soluble metallic salts and a coloring pretreatment in which DC wave form is energized with the aluminum material as an anode is executed and then AC electrolytic coloring treatment is executed in the same electrolytic coloring treating bath. In this case, the coloring pretreatment is executed until ultimate voltage value and ultimate current value which are previously set are attained.