An insulating sleeve comprising a flat, elongated blank with straight top and bottom edges and end edges which are joined together at a glue flap. The dual mode resonator is capable of sustaining two frequency vibration modes simultaneously. On the other hand, while the polisher is idling, the controller starts and stops the pump intermittently at regular intervals. 5\xd7103 Pa to 5\xd7106 Pa at 150\xb0 C.