Yoshida Kogyo K.k.

Masatake Tsuboi

Kazuo Aikawa

Hatsuo Hirono

The invention provides a novel and improved method according to which the surface of a shaped article of aluminum or an aluminum-based alloy is provided with decorative streak patterns electrolytically engraved in the surface which can be subsequently colored to increase the decorative effect with uniform distribution over whole surface of the aluminum article. The method comprises first subjecting the anodically oxidized aluminum article to an anodic direct current electrolysis in an electrolytic solution containing a specified electrolyte and then carrying out a cathodic direct current electrolysis with the aluminum article and the counterelectrode kept as before in the same electrolytic solution as used in the first anodic direct current electrolysis with reversed polarity to give uniformly distributed streak patterns on the surface of the aluminum article. The surface of the aluminum article thus provided with the streak patterns is subsequently anodized to enhance the corrosion resistance and then subjected to a coloring treatment.

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Kurobe, Japan

Masatake Tsuboi