Abstract: A method in which aluminum and aluminum alloys are subjected to anodic oxidizing treatment by use of a novel electrolyte to form a good colored and oxide film on the surface thereof. The electrolyte comprises an organic acid solution resulting from the sulfonation of fumaric acid (hereinafter tentatively referred to as the sulfofumaric acid) as a main liquid, into which either oxalic acid as an organic acid, or sulfuric acid or metal sulfate as the inorganic acid are added.
Abstract: A method for color-anodizing (hereinafter referred merely to "coloring") aluminum and aluminum alloys in a short period of time. The method comprises adding sulfosalicylic acid or sulfophthalic acid and along with sulfuric acid to a solution, of which the main ingredient is citric acid, succinic acid, to form an electrolyte and effecting anodic oxidation on surfaces of aluminum and aluminum alloys with the electrolyte to form a colored oxide coating.