I just figured out what you meant. That makes sense. I do know that when I heat food on a Corelle plate I can take the plate from the microwave and it does not burn my hand. The food is hot and I can eat from the same plate.

When using the stoneware the plate is too hot to handle but the food is not up to temperature.

I had assumed it was drawing heat solely from the food. I have always heard you cannot put a dry plate into a microwave because there needs to be water to absorb the energy.