As with grinding, polishing is performed on the surface of a workpiece, whether wooden or metal, in order to achieve a mirror-like surface finish. In other words, reflection of light, with as little transmission as possible. Brushes with either hard or soft bristles (according to the hardness of the workpiece) polish with bristles coated with abrasive material or synthetic diamond. Polishing may also be performed with steel or stainless steel fibers, according to the material’s properties and aggressiveness of the polishing action.