Abstract: The invention is for an improved process for chemically forming a protective, color receptive coating on the surface of aluminum. The aluminum may be aluminum parts or substrates coated with a layer of aluminum. Absent conventional steps such as water rinses and the like, the process comprises cleaning the aluminum surface to the extent necessary, including desmutting, and contacting the part with a spray comprising an aqueous alkaline solution of a ferricyanide compound, with or without added oxygen, for a time sufficient to form the coating. The treatment is believed to be a chemical oxidizing step similar to the formation of an oxide film electrically using a conventional anodizing process.