We all have ceramics at home in the form of pots, plates, mugs, and more. And sometimes you just want to heat a quick snack on a ceramic plate or warm up your milk in a ceramic cup.
But is that really a good idea?
Most types of ceramics can be used in the microwave without any problems; they won’t contaminate your food and they don’t become burning hot.
However, there are a few exceptions to the rule, so let’s look at which ceramics are microwave safe in more detail!.
What types of ceramics are microwave safe?
Most ceramic, china, earthenware, stoneware, porcelain, and bisque ware are safe for heating in the microwave.
Whether ceramics can be placed in the microwave or not depends for a large part on what type of clay it’s made from and at what temperature it has been fired.
Why are some ceramics not microwave safe?
Some ceramics are not microwave safe because they absorb the microwave radiation faster than the food or liquid they hold. The ceramics will heat up first and you could easily burn yourself by touching it. As a result, your ceramics will be super hot, while your food will remain cold.
There are several reasons why certain ceramic pieces heat up in the microwave. The three most common are:
Porosity: Porous ceramics such as earthenware have a rough texture and are generally lighter compared to other types of ceramics. This type of pottery isn’t microwave safe without any glaze.
Since the pores easily absorb water and other liquids, they can heat up considerable when placed in the microwave. Moreover, porous ceramics without a glaze are generally not food safe either.
However, once they are glazed, porous ceramic are actually better for the microwave than really dense ceramics such as stoneware, because they porous structure is more resistant to thermal shock.
For more information, you can ready our article on stoneware vs earthenware.
Embroidery and Decorations: Ceramic pieces with embroidery or painted decorations should not be placed in the microwave. The heat will have a negative effect on the pigments, so the colors will look start to look faded after using the microwave.
Metal linings: Placing metal in a microwave is never a good idea, and ceramic with steel linings or gold/silver trims is no exception to this rule. The metal will quickly absorb the microwave radiation and heat up rapidly, potentially causing fire.
How can you tell if ceramics are microwave safe?
Most store-bough ceramics have a symbol or text at the bottom which will tell you if you can safely place it in the microwave or not. If nothing is indicated on the ceramic itself, you can sometime find the information on the packaging as well.
However, if nothing is shown on the ceramic piece itself or the packaging, you’ll have to carefully test yourself if it is microwave safe.
How to test if your ceramics are microwave safe?
To test if your ceramics is microwave safe, you want to fill it with water and heat it in the microwave for 20 to 30 seconds at a time. Then check the temperature of your ceramic and the water separately. If the water warmed up while the ceramic remained at room temperature, it’s probably microwave safe.
However, if the ceramic warmed up more or to a similar degree as the water, it isn’t microwave safe.
If your microwave isn’t very strong, just heating for 30 seconds might not be enough to really feel a temperature change. In that case you can slowly increase the heating time and repeat the process.
Can handmade ceramics be microwaved?
Most homemade ceramics are microwave safe just like store bought ceramics, as long as the handmade ceramics have been glazed and fired at high temperatures. However, unglazed or painted pieces are should not be used in the microwave.
Make sure that neither the clay nor the glaze you use contain any heavy metals such as cadmium or lead, since these can leach out of the ceramic and cause various health related issues.
If you want to know more about glazing and all the steps leading up to it, then read our article on the complete pottery process.
What about the dishwasher?
After heating your food or drink in the microwave, you’ll have to clean your ceramic plates and cups.
Nobody likes doing dishes by hand, so you’ll probably be tempted to place your ceramics in the dishwasher. But that’s not always a good idea.
For more information, read our article on dishwasher safe ceramics.