Abstract: After three or four abrasive rock tumbling steps with successively finer and finer adhesive, the rocks are tumbled with pieces of an elastomer, for example plastic foam. The plastic foam may be pulyurethane foam. The result is a higher polish than could be achieved by prior abrasive and finishing approaches.

Abstract: After three or four abrasive rock tumbling steps with successively finer and finer adhesive, the rocks are tumbled with pieces of an elastomer, for example plastic foam. The plastic foam may be polyurethane foam. The result is a higher polish than could be achieved by prior abrasive and finishing approaches. A polishing compound may be embedded in the polyurethane foam. Advantages of doing this include that the user gets multiple polishings out of the material base, there is less breakage of the rocks during tumbling process, and the tumbling mix will not “sludge up” if the user were to let the barrel sit after tumbling.