Can You Microwave Cold Glass? (Solved)

Categorized as Microwave
Can You Microwave Cold Glass

Microwaving food in a cold glass container has always been a controversial topic. Some people say that if you put cold glass in the microwave, it will explode, and others say it is completely safe. This article will explain whether or not putting glass containers in the microwave is dangerous.

Can You Microwave Cold Glass?

Microwaving glass from the refrigerator is a big no! If you put a glass container from the refrigerator into the microwave and then turn it on, it will most likely break or shatter. This is due to the varying temperature of both the glass container and microwave. The hot microwave rapidly heats up the cold glass, causing it to vibrate violently and shatter due to thermal stress.

Regardless of whether the glassware is made of natural or synthetic glass, you can’t microwave it from a cold state.

Can You Microwave Glass Dish?

In general, most glassware containers such as glass bowls and plates can be heated in the microwave.

Compared to other materials, such as plastics or ceramics, glass has the ability to withstand very high temperatures. However, depending on the designs and the materials used to make glassware, some glasses may not be microwave-safe.

Here’s a quick guide on which glassware you can and can’t heat in the microwave:

Microwave Safe Glass Containers Not Microwave Safe
Glassware that has been labeled as microwave-safe Glassware with metallic trims
Glassware that has passed the microwave-safety standardsColored glassware
Glass-ceramics

Glassware with labels for microwave-safe

The easiest and quickest way to determine if particular glassware is safe to microwave is by checking whether you can find a label on it saying that it’s safe for microwaving. This label can usually be found on the bottom part of the glassware. If you can’t find any such label on your glassware, look for markings in the glass itself which indicate that it is microwave-safe.

If you come across a glass bowl or plate that has no label or markings on it, check the packaging it came in. Some manufacturers may include some directions for use on the packaging, which can be helpful in determining whether the glassware is microwave-safe, or they may provide a website address where you can find information on the product.

If you look at your dish and see that it isn’t labeled as microwave-safe, cross-check the materials with the list of non-microwave safe glassware above.

Glassware that has passed the microwave test

There is a simple way to test whether your glassware can withstand the high temperatures of the microwave by following the following steps:

Fill a glass or other glass dishes you want to test with water. Put the dish in the microwave, and turn it on high for 1 minute. Take it out, then test the temperature of the water by carefully checking the container and the water with your hand. If the container feels hotter than the water, then it’s definitely not safe to microwave. If you happen to have some way of measuring heat in the glassware and water (such as through infrared thermometers ), this would also be helpful.

The reason we’re doing this test is because microwaves heat glass by transmitting heat energy into the container. The water is used here to absorb any excess heat in the container. If the microwaves aren’t able to penetrate through the glassware or if they are blocked, it will make using the microwave oven unsafe as well as reduce its efficiency.

Glass ceramics

Glass ceramics are mostly considered safe to microwave. They hold up well against heat, which is why manufacturers make them microwave safe. However, since they come in different thicknesses, you need to ensure that your ceramic has the microwave-safe stamp on it.

Additionally, you can do the same quick test like the one mentioned earlier to determine if it is indeed microwave-safe. Just fill them up with water and heat them in your microwave. 

Glassware with metallic Trims

When you use dishware containing metal lining, it might cause sparks when heating with a high setting in the microwave oven. The metal lining might also heat up and cause burns on your hands if you are not careful while removing the dish from the microwave oven.

Colored glassware

While it looks great to microwave your food in colored glassware, this is not recommended as some additives and dyes used in making the glasses may leak into your food while heating.

Is It Safe to Heat Food in a Glass Dish in Microwave?

Aside from glass with metal lining and colored glass, most glass dishes are safe to use for heating food since it is usually chemically inert. This means, unlike plastic wrap, there’s no chemical reaction that occurs between the glass and food when heated.

The Differences Between Microwave Safe and Non-Microwave Safe Glass?

The main difference between microwave-safe and non-microwave-safe glass is the tiny air bubbles trapped in the glass. These air bubbles can be formed as a result of the manufacturing process. When they are heated in a microwave oven, they will expand, and to a certain extent, the air bubbles may cause cracking or breaking of the glass.

In a microwave-safe glass, the air bubbles are intentionally removed so that they won’t expand when heated.

How to Safely Microwave Cold Glass From the Refrigerator?

If you are planning to reheat some food in a cold glass container taken from your refrigerator, there are some precautions you need to take to make sure the container is not damaged, and the food is reheated safely.

When the container is taken out of the freezer, it is covered with a layer of cold condensation. So the first thing you should do is wipe it off. Then, if the food is frozen solid, let it sit for 30 minutes at room temperature to thaw it out.

After the food is defrosted, the next thing to do is heat it in the microwave. Remember always use a potholder or kitchen gloves when taking the container out of the microwave oven to the risk of getting burnt.

If you don’t have time for your refrigerated glass to come to room temperature, you can always heat it slowly in the microwave oven. Aim for the lowest setting first, gradually increasing the power until you reach the desired temperature.

If you still want to use a container that is not microwave-safe, make sure to start with short heating times and give your food a good stir every few minutes. This should help the food heat evenly and prevent the container from breaking in the process.

Related Questions:

Is Pyrex Glass Microwave Safe?

According to Pyrex Safety and Usage Instructions, it is safe to use Pyrex glassware in microwaves. Although it is safe, you must not be careless and follow the instructions provided on the product packaging and manufacturer’s website.

Final Thoughts

Microwaving cold glass is out of the question. The chilled glass will break or shatter when exposed to temperature fluctuations in a high heat microwave.

The best way to know for sure if your dishware or glasses are microwave-safe is to look at the label on them! If you don’t seem to have any labels and can’t find anything online about whether or not that specific type of dishware will break in the microwave, try the microwave test.

Be sure to avoid microwaving any glass dishes that have metallic trimming or dye (such as colored glassware).

Be careful when you microwave cold glass and always follow the safety tips that I have laid down in this article!