Although aluminum and aluminum alloys can naturally form an oxide film in the atmosphere, the film is thin (40-50a), loose and porous. It is an amorphous, uneven and discontinuous film, which can not be used as a reliable protective decorative film.

With the continuous development of aluminum products processing industry in Changshu, anodizing or chemical oxidation methods are more and more widely used in industry to form a layer of oxide film on the surface of aluminum and aluminum alloy parts, so as to achieve the purpose of protection and decoration.

Aluminum alloy hard aluminum oxide film has high strength, good wear resistance and excellent corrosion resistance. After years of research, Changshu dura mater adopts special processes according to different alloy components to produce oxide films of different colors such as black, yellow green, silver gray and tan. The color of this kind of oxide film is non-toxic and harmless, durable, does not fade under high temperature and high pressure, and does not decolorize in water. It has a very good decorative effect. Changshu dura mater can be used for inner pot of electric rice cooker, packaging box of medical devices, cylinder, oil cylinder, printing and so on.