Its unsafe for the microwave if its warm

Heres a quick test for glass: Microwave the empty container for one minute. Its unsafe for the microwave if its warm; its OK for reheating if its lukewarm; and its OK for actual cooking if its cool.it is important to realize that food cooked in a microwave oven does not become radioactive. Nor does any microwave energy remain in the cavity or the food after the microwave oven is switched off. In this respect, microwaves act just like light; when the light bulb is turned off, no light remains.