Can You Put Glass in the Microwave?

Technically Reviewed by Igal Geiler on Mar 20, 2024 | Written by Igal Geiler

To avoid ruining your food, destroying the microwave oven, and causing a fire in the kitchen, you need to ensure that all the kitchenware items you are placing in it are microwavable, especially the ones made of glass. This article will teach you how to know if a cup is microwave safe and what symbols to look for on dishes and containers.

Can You Microwave Glass?

It is not safe to use dishes made of glass if there is a picture on it, especially with gold paint. Home paints contain metal that will create sparks. But is all glass microwavable? General oven usage guidelines name most glassware, specifically Glasbake microwave, safe for low temperatures. They also name the borosilicate glass microwave safe for up to 840°F.

But can you microwave tempered glass? Yes, tempered glass and glass ceramic dishes are ideal for use in the microwave, but they should also have a uniform surface. Remember to follow the correct cooking regime and avoid sudden temperature changes.

How Long Can Glass Be In the Microwave?

Understanding the operation principle of a microwave oven is essential for comprehending the basics of safe microwave oven usage. Electromagnetic waves, generated by a specialized device called a magnetron, force the molecules of water, sugar, and fat in the food to move faster. As a result, the temperature rises, and the food cooks from the inside out.  

This is why, when choosing glass microwave cookware, you need to take into account that it will undergo the same process as the food it contains. On the one hand, the heater is fragile when heated because it contains metal components. On the other hand, when heated, toxins will settle, which is harmful to health. Not all glassware on the market can withstand being heated in a microwave oven. Only specialized, heat-resistant glass products are considered safe enough.

You can safely microwave an item made of non-tempered glass for up to 5 seconds, while tempered glass can withstand up to 10 seconds. However, you won’t be able to use glassware for cooking, baking, or even reheating a big portion of food, as this takes at least 2 minutes.

Please note that ordinary glass withstands the difference between the water temperature and ambient temperature by up to 140°F. For example, if your kitchen is 68°F, you can safely fill a glass container with 176°F water.

What Marking on the Dishes is Suitable for the Microwave

Firstly, you need to know that kitchenware made of microwavable glass is only cheap if you get it on sale. Secondly, before committing to the purchase, always look for the symbols that indicate that this item can be used in the microwave. Here is what they may look like:

• a square with wavy lines inside;
• letters saying Microwave oven safe or MICRO;
• a microwave icon with wavy lines or a plate inside;
• a pictogram of a plate, cup, or other type of tableware with several wavy lines above it.

If you do not see any of these markings on the dishes, it is better not to risk putting them into a microwave. The same pictograms crossed out indicate that the dishes cannot be used in the microwave.

Conclusion

It is worth remembering that in the process of using any type of household appliance, it is important to follow some rules. 

First of all, it concerns the choice of dishes. If you follow all the advice of experts, you can continue the operation of the microwave oven and greatly simplify the process of cooking.