It can be polished by an ultrasonic polisher, which is polished by a diamond polishing paste. The tools used are sawdust, bamboo chips, brass rods, etc. When polishing, polishing paste is coated on wood chips or bamboo chips, and the cavity to be polished is polished. When polishing, coarse polishing paste (such as W7) should be used first, then fine polishing paste (W5) and finally the finest polishing paste (W3.5). The polished surface can achieve a mirror effect.