I was inspired by one of the messages responding to my earlier message about microwave ovens, so I did 2 simple experiments:
1. I put a half sheet of plain paper (ordinary copy paper from Staples) into my microwave and set the machine for 65 seconds at the highest power. It was barely warm at the end of 65 seconds.
2. I put a few drops of water on the paper and again put it in at 65 seconds on high power. It came out perfectly dry and barely warm.
65 seconds in this machine is plenty for most ordinary purposes. If the paper didn't even get hot after 65 seconds, I doubt that it will.
Next experiment: I'll ask the butcher at the supermarket for some of the stuff from the foam container and repeat the experiment above with that stuff. Then I'll do it with a foam tray.