(1) Surface pretreatment: clean the profile surface by chemical or physical methods to expose the pure substrate, so as to obtain complete and fine artificial oxide film. It can also obtain mirror or matte (Matt) surface by mechanical means.

(2) Anodizing: after surface pretreatment, the surface of the profile will be anodized under certain process conditions to form a fine, porous and strong adsorption alumina film.

(3) Sealing: the pores of the porous oxide film formed after anodization are sealed to enhance the anti pollution, anti-corrosion and wear resistance of the oxide film. The oxide film is colorless and transparent. By making use of the strong adsorption of the oxide film before sealing, some metal salts are adsorbed and accumulated in the film hole, which can make the profile appearance show many colors other than its original color (silver white), such as black, bronze, gold and stainless steel.