Ceramic, like porcelain, bone china, and glass, tend to not get hot in the microwave if they’re well-made and thick enough to withstand the heat conducted from the food they contain. There’s also such a thing as microwaveable plastic too, which is marked on the bottom as microwave-safe.
So does ceramic get hot in the microwave or not? Usually not but it depends on the ceramic. A good piece of a ceramic bowl, dish, plate, or earthenware shouldn’t get hot in the microwave easily, or else it’s not considered microwave-safe.
Further reading: Does Bone China get Hot in the Microwave or Not?
Ceramic Shouldn’t Get Hot Easily in the Microwave
The most microwave-safe variant of ceramic is the dry, unglazed type. However, there’s a catch. As the microwave’s micro or mini radiowaves heat up the water by making its molecules “excited”, this affects the ceramic dish as well. The heat produces is transferred to the dish by conduction.
If the water gets to a certain temperature, like at the point of being superheated, even cool ceramic dishes will become hot to the touch due to all that water hotness. Just because the ceramic is microwaveable, it doesn’t mean it’s immune to heat.
A couple of minutes or seconds of heating won’t affect the ceramic, but if the water gets too hot it will affect the dish itself. To be more specific, superheated water can cause thermal expansion. The ceramic dish gets thermal expanded too much, it will end up breaking.
Metal, in contrast, is good at microwave deflection or reflection. This is why they’re used to shield the oven walls to protect the magnetron, electronics, and you from being bombarded with microwaves as well.
Why Do Your Microwave-Safe Dishes Get so Hot?
Just because your ceramic dish is microwave-safe doesn’t mean it won’t get hot. Every material is going to have different reactions to radiowaves. Even if radiowave has a neutral reaction to ceramics due to its lack of water molecules inside, the conduction from hot food or beverage can affect them.
Food and water can absorb microwaves excellently. They have a tendency to get the hottest when inside the microwave oven. Superheated anything can end up conducting heat onto the ceramic, leading to thermal expansion and breakage.
It’s also dangerous to let ceramic heat up extremely then let it cool down suddenly. This can lead to ceramic breakage as well. Most anything you heat up then suddenly cool down with cold water or room temperature will tend to break up.
Can You Microwave Cold Ceramic?
Metal shouldn’t be put inside the microwave. Metal containers should never be microwaved. Glass and ceramic are the best materials to use for microwaving food. Plastic can be used for microwaving too as long as there is a tag that says it’s microwave-safe.
In regards to microwaving cold ceramic, maybe not. Let it get warm gradually by leaving it in a room-temperature environment. As mentioned earlier, sudden temperature changes that lead to thermal expansion and cold contraction lead to stress that cracks your ceramic.
Instead of putting your cold food on a cold dish straight from the refrigerator to your microwave, it’s better to transfer that cold food into a room-temperature ceramic dish. If your cold dish heats up suddenly then it could crack.
Plates That Don’t Get Hot (Easily) in a Microwave
Thick room-temperature ceramic plates take a long time to get hot from microwaved hot food due to its thickness. These work best when microwaving food. You can also avail of cookware from companies that use similarly thick glassware or high-quality microwave-safe plastic such as Progressive Cookware.
We also suggest Nordic Ware and microwave-safe sealable food storage with labels. As much as possible, you should make sure that plastics have markings saying they’re microwave-safe. When it comes to ceramic dishes and chinaware, you usually believe they’re automatically microwave-safe.
There’s also Corelle Dinnerware made of glass and ceramics. They specifically can be used with microwaves for food reheating. They can also take preheated conventional ovens with temperatures reaching 176° C or 350° F.
The caveat for them is either a warning label saying they’re not microwave-safe or if they’re extremely thin, so therefore they could heat up due to superheated food or beverage and thermally expand to the point of breakage.
Is It Safe to Microwave a Ceramic Mug?
A ceramic mug should be thick and labeled as microwave-safe. The danger of microwaving a non-microwaveable mug is that it could break or crack when it’s heated.
As mentioned countless times before, a label ensures that when you microwave a container, it won’t release any toxins or melt. Earthenware and ceramics don’t easily break or melt, thus making them perfect for reheating or cooking.
The label of microwave-safe doesn’t ensure nontoxic results though. However, when you need to heat liquids to boiling or a superheated state, you absolutely need to use a ceramic mug labeled microwave-safe even though most people conclude that ceramic equals microwave-safe sans label.
When a non-microwaveable mug is microwaved, expect it to either absorb the heat easily until it breaks or have metal that deflects the microwaves all over. It also risks becoming hotter than your food.
How Hot Can Ceramic Get Before Its Breaking Part
Ceramics, like most other earthenware types, can take a lot of abuse and thermal stress. This is especially true of ceramics labeled specifically as microwave-safe.
Many of them can take preheat temperatures of 176° C or 350° F or something similar with microwaved food temperatures. Certain thick ceramics can even perform similarly to heatproof glass and glassware.
Earthenware, after all, is kiln-fried at “relatively” low temperatures ranging from 1037°-1093° C or 1900°-2000° F. They’re neither impermeable nor vitrified. Therefore, they’re safest for use in reheating instead of cooking.
They can absorb heat from hot food (not superheated) while remaining cold themselves. They’re as heatproof as vented microwaveable plastic bags, parchment paper, wax paper, wood, straw baskets, paper products, and oven-cooking bags.
When Push Comes to Shove
Ceramic, glass, paper, and (certain) plastic containers regularly get used for microwave reheating or cooking due to how radiowaves easily pass through them, leading to them not getting hot easily. However, they’re still heat conductors, so the food being heated could make them hot.
Ceramic is considered microwave-safe if it doesn’t get easily hot while being microwaved. If it’s cool to the touch while the food is piping hot after a microwave session then you’re assured you can use it for microwave-related cooking and reheating.
- “Why Does Ceramic Heat Up In Microwave?” ExpandUSCeramics.com, Retrieved March 27, 2021