If you have a poor quality, low density (often mass produced), ceramic plate, there are tiny air bubbles inside it. These vibrate when the microwave runs, heating the plate faster/more than the food. This is the same reason why some mug handles get hot enough for 2nd or 3rd degree burns in the microwave while others never get the “microwave handle of death”. Better made ceramics will have far fewer (or none) of these bubbles. This is why usually hand made pottery will not heat up like this, while factory stuff that was quickly poured into molds often will.
Often is a stretch. Plenty of the cheap mass produced stuff still doesn’t heat up at all. It’s almost exclusively older stuff that I notice heating up these days
That’s not how RF works. For one thing, microwaves run at 2.4GHz, which means they can’t “see” physical features smaller than a few centimeters (to greatly oversimplify what’s going on). The miniscule bubbles simply aren’t a big factor.
Rather, what’s happening is that the ceramic (probably the glaze if we’re honest) has a higher cross section and/or lower specific heat than the food, especially when it’s frozen. It absorbs more energy and heats up faster.
I would also expect far fewer and smaller bubbles with industrial slip casting (“pouring into a mold”) than manual production.
If you have a poor quality, low density (often mass produced), ceramic plate, there are tiny air bubbles inside it. These vibrate when the microwave runs, heating the plate faster/more than the food. This is the same reason why some mug handles get hot enough for 2nd or 3rd degree burns in the microwave while others never get the “microwave handle of death”. Better made ceramics will have far fewer (or none) of these bubbles. This is why usually hand made pottery will not heat up like this, while factory stuff that was quickly poured into molds often will.
Often is a stretch. Plenty of the cheap mass produced stuff still doesn’t heat up at all. It’s almost exclusively older stuff that I notice heating up these days
That’s not how RF works. For one thing, microwaves run at 2.4GHz, which means they can’t “see” physical features smaller than a few centimeters (to greatly oversimplify what’s going on). The miniscule bubbles simply aren’t a big factor.
Rather, what’s happening is that the ceramic (probably the glaze if we’re honest) has a higher cross section and/or lower specific heat than the food, especially when it’s frozen. It absorbs more energy and heats up faster.
I would also expect far fewer and smaller bubbles with industrial slip casting (“pouring into a mold”) than manual production.