Sandpaper is used to add a nice, smooth finish to a piece of wood or to an object made out of timber. When a fine smooth finish is required on an object's surface, d
…ifferent grades of sandpaper are used to rub down the surface, starting with the coarsest grade and working through to the finest grade. The rough texture of the sand stuck to the surface of the paper scratches off the roughness of the object's surface making it progressively smoother. Frequently sandpaper is used between the application of layers or "coats" of paint. Sandpaper may also be used to file fingernails or remove rough areas of calluses on the skin. (MORE) 