2. Mechanical method: sandblasting cleaning, glass or ceramic particle shot blasting cleaning, annihilation, brushing and polishing. Mechanical methods may wipe off the pollution caused by previously removed materials, polishing materials or annihilation materials. All kinds of pollution, especially foreign iron particles, may become a source of corrosion, especially in humid environments. Therefore, the mechanically cleaned surface should preferably be cleaned formally under dry conditions. The mechanical method can only clean the surface and cannot change the corrosion resistance of the material itself. Therefore, it is recommended to re-polish with polishing equipment after mechanical cleaning and seal with polishing wax.