sandpaper without holes  does not have any holes, and its role is the same as that of porous sandpaper, which is mainly used for grinding the surface. Compared with perforated sandpaper, the surface of non-perforated sandpaper covers a larger area, the sand is more dense, and the grinding force is greater. However, because the surface has no holes, it is easy to card grinding, resulting in blockage, poor heat dissipation, easy to damage the sand, sandpaper is easier to lose the grinding ability, sand is easy to hot melt and leave marks.