Sometimes you want to heat up a plate before you put food on it, especially if the food is going to be hot when it’s done. You might think that you can just pop the plate in the microwave for a few seconds, but that won’t work. The plate will stay cold and the food will get cold as well.
So why does an empty plate not heat in the microwave? The answer is relatively simple.
Microwaves heat food by agitating the water molecules in the food.
If there is no water in the food, then there is nothing for the microwaves to agitate and therefore no way to generate heat.
You can, however, heat an empty plate in the microwave if you put a small amount of water on the plate. The water will absorb the microwaves and turn to steam, which will in turn heat up the plate. Just be sure to use a small amount of water, otherwise, you’ll end up with a mess in the microwave.
So why do some plates get hot and others don’t?
A long explanation short, Any plates, cups, or bowls that heat up in the microwave without being wet or having food on them are not microwave safe.
They are made of different materials that Microwaves can heat up, which can be a fire hazard as well as release chemicals into your food.
They will also slowly degrade to the point where they chip, crack or become extremely brittle. They may also cause burning when you pick them up out of the microwave because of the heat retention.
Microwave-safe dishes do not interact with the 2450 MHz microwaves used in home ovens to the point where they get hot. They are basically invisible and the waves pass directly threw them without interacting. That’s why an empty plate or ceramic cup does not heat up in the microwave.
Look for a microwave-safe symbol or stamp on the bottom of the dish before microwaving it.
If there is no symbol, the best way to test if a dish is microwave safe is to put a cup of water in it and microwave it for one minute on high. If the dish stays cool, it can go in the microwave. If it gets warm, it’s not microwave-safe.