Fiber abrasives (silicon carbide): fiber abrasives are strong with low flexibility. Nylon fibers are coated with abrasive material, usually silicon carbide. Used mainly for working of marble or non-metal materials. Brushes with silicon carbide coated are available with a very fine grain, enabling attainment of a high quality surface. These brushes have a long lifetime, and in recent years have been significantly applied in the auto and aerospace industries.