I used to run water on a towel under the tap. Wring out the excess and place the towel in the microwave. Mine will do it in 45 seconds but you have to try it because all microwaves are not created equal. Find the setting that works and be careful not to burn yourself before you do. I don't do this because it is more trouble than it is worth and I've been cold water shaving for a few years now, but give it a shot, you might like it.