A NEW METHOD FOR COLORING ANODIC OXIDE FILMS ON ALUMINUM
A new hydrothermal treatment of anodic oxide films on aluminum was proposed by the use of water containing cobalt(II) oxide at 280 °C in an autoclave. A reaction of the alumina on the film with cobalt(II) oxide resulted in the formation of cobalt(II) aluminate. The color of the film was a vivid bright blue.