What is the function of sandpaper?

Sandpaper is a type of grinding material used to grind paint, putty, and other surfaces of metals, wood, plastics, etc. to make their surfaces smooth and even. There are two types of sandpaper, dry sandpaper and water sandpaper, which are made from unbleached sulfuric acid wood pulp. The paper is strong, wear-resistant, and has good water resistance. The grinding material is adhered to the original paper with adhesives such as gum, and dried to make it