Years ago Martha Stewart had instructions for making a rice bag using a knee sock. She said to heat it for two minutes, but if you use a sock with nylon in it, be careful! Nylon melts. I used cotton fabric and made long tubes, instead of using socks. This wasn't for keeping plates warm, though, but for putting across your shoulders to alleviate stiffness and/or pain. It really works, but just heat for 1 minute. It stays warm for quite a long time and feels so good. Also good for cold feet, instead of a hot water bottle that can leak.