Bobbing Compound Dry. Jewelers often use a pre-polishing compound on soft, non-ferrous metals such as gold, silver, brass, and copper. This compound helps to achieve a uniform finish on the metal surface in preparation for final polishing or buffing. It is moderately abrasive, making it ideal for removing fire scale and scratches from gold, sterling silver, brass, and nickel. By using this pre-polish, jewelers can effectively prepare the metal surface for a smooth, polished finish.