Can Glass Go in the Microwave Oven ?

Microwaves are stingy appliances. There are many rules about what can go into a microwave oven that does not necessarily apply to ovens in general.

It is often difficult to determine whether or not something can go into an oven simply because they are so convenient.

The convenience and universality of microwaves makes us think that we can put almost anything inside without any problems. As we all know now, Styrofoam and aluminum foil are a no go.


Styrofoam will cook and lead to a chemical reaction that will taint the food. Aluminum foil can spark and even catch fire due to how the microwave works.

Glass, on the other hand, is a different story. It can be a very particular substance when going into the microwave. What happens as you heat glass in a microwave really depends on what you place inside it and how long it is in.

Can Glass Go in the Microwave Oven ?

Natural Glass

For the most part, natural glass is safe for cooking in the microwave. This goes especially for those dishes and cups that are made of thick glass, as the heat will not affect it much.

For this reason, you can put the casserole dish in the microwave without repercussions.

glass go in the microwave oven

However, be careful about the rules of thermodynamics. If the glass has been in the refrigerator or freezer, you should give it time to warm up outside the microwave first. This is because the molecules in the glass are frozen still when they are cooled down.

As the glass heats up, the molecules begin to move faster and faster. If it is heated up too quickly, as is what happens in the microwave, then the glass will be put under stress.

When this happens, the glass may crack or even explode, depending on how cold it was when it was placed in the microwave.

Recently refrigerated glass will be okay to place in the microwave. As a general rule, if the glass is frosty DO NOT place it in the microwave until the frost has melted.

If it is gathering condensation after leaving the refrigerator, give it a few minutes to warm up before heating it.

Lastly, if you are heating glass you should be cautious. Glass is a conductor of heat, meaning it will heat up itself as its contents are heated.

This distinguishes glass from plastics, which generally do not conduct heat. When you microwave glass you should take care as you remove it from the microwave.

Synthetic Glass

Synthetic glasses such as Pyrex are also safe to place in the microwave. This is because they do not react to the microwaves that are sent out by the oven.

Despite this safety, you should adhere to the tips that were previously mentioned for natural glass. While Pyrex is safe, it can still be subject to temperature constraints.

There are some rumors that synthetic glass will explode due to its contents reacting with the microwave. These rumors are unfounded.

However, if you are in doubt you can always check on the bottom of the dish to see if it is microwaveable. Most dishes will be marked as microwaveable or not.

Microwave Caution

A microwave is a convenient appliance with many uses for heating food and other materials. You should always take caution when using the microwave as it has many particularities that are not applicable with conventional ovens.

In any case, a microwave is a great convenience to have in the kitchen and when used correctly it can cut down on cooking time for a wide range of food. When you are using a microwave, you should make sure the container is microwave safe.

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