Because it is very thin, the wax itself forms a protective layer. Light diffraction produces patterns because sandpaper is too rough. Hemp wheels (wheels made of hemp) are generally used, and sandpaper is generally not used for metal polishing. Polishing paste, installed on a polishing machine, quickly rotates to polish metal. It used to be called grinding paste, but it is very expensive. Besides, grinding paste can't be polished with ordinary paper and towels, and it is easy to scratch the metal surface, so cosmetic paper is used. In the past, polishing molds were polished by a polishing machine first, and then finely polished with grinding paste, which could turn the steel plate with hardness of 52 into a mirror. If you don't want to rust, you can oil it, but you should oil it evenly and cover every place with hemp wheels. Those with higher requirements should use cloth wheels. This simple grinding wheel can be tried on an angle grinder. Ordinary shops selling grinding wheels and the like can sell them. The demanding should be rough first. Metals are very lively. It is oxidized at room temperature, forming a dense oxidation curtain on the metal surface, which is an alloy. When you remove the twilight with gauze, the metal inside is exposed to the air and oxidized to gray. It can be polished by angle grinder and grinding wheel, but it is smooth and flat. Then put on a polishing cloth wheel and dip it in polishing wax, the effect is better and the efficiency of manual polishing is too low. Adding a metal polishing agent into the polishing solution to passivate the metal surface.