Can You Microwave Cold Glass? [Here’s the Answer]

Glass is a prevalent material used in various products, including food and beverage containers, cookware, and automotive parts. While glass is a sturdy material, it does have some drawbacks. One of these drawbacks is that glass is highly susceptible to heat, and it’s essential to know if you can microwave cold glassware or not.

Can You Microwave Cold Glass?

No, you should not put a cold glass in the microwave because the sudden temperature change can cause the glass to break. The glass cannot be microwaved from a cold state because it will vibrate violently and shatter due to thermal stress. A cold glassware item cannot be microwaved, regardless of whether it is made of natural or synthetic glass.

In this guide, we’ll cover can you microwave cold glass, the dangers of microwaving glass, and offer a few tips for avoiding these dangers.

Can You Microwave Cold Glass

Can You Microwave Cold Glass?

It’s best not to put cold glass in the microwave because when you do that, it’s more likely to break. Glass is a poor conductor of heat, so it takes longer to heat than metal.

Do not use Pyrex or any other dish labeled “oven-safe” or “microwave-safe.” These dishes are designed for heating food up in the oven or microwave and then bringing them up to room temperature before serving. If you put them in either appliance while they’re still cold, the heat can cause them to crack or shatter.

If possible, place your glass in a microwave-safe dish or bowl that is large enough to move around freely without being damaged by another object in the oven (this is especially important if you have a turntable). In general, it’s best not to stack dishes on top in a microwave as this increases the chances that something will fall over and break during cooking (or worse).

Cover your glass with plastic wrap before putting it into the microwave. This will help keep steam from building up inside your microwave and causing pressure build-up, which could lead to shattering if there were cracks.

Is It Safe to Microwave Cold Glass?

Microwaving cold glass can be dangerous. The temperature of the glass may be below the melting point, but once it is heated up, it will start to soften and deform. As it heats up, its surface will become uneven and may even crack.

Microwaving cold glass is not a good idea because it can cause the glass to explode. The same is true with any other cold liquid or food in a microwave oven. When you place a cold glass in a microwave oven, the glass will cool down more rapidly than the water inside it.

Why Does Cold Glass Shatter in the Microwave?

The cold glass shatters in the microwave because of thermal stress. Thermal stress occurs when there is a sudden temperature change, causing the inner and outer layers of the glass to expand and contract at different rates.

The sudden temperature change can cause the glass to expand too quickly and shatter. Microwaves work by using electromagnetic waves to heat food. These waves cause the food’s water molecules to vibrate, generating heat.

When microwaves hit a piece of cold glass, the glass absorbs the energy and heats up quickly. The inner layer of the glass expands faster than the outer layer, causing the glass to crack or shatter.

Can You Microwave Cold Pyrex Glassware?

You can microwave cold Pyrex glassware, but you should avoid doing so if possible. If you must microwave cold Pyrex glassware, put it on a plate or in a bowl of water to help out the heating.

Pyrex glassware is made from borosilicate glass, resistant to thermal shock. This means that it can withstand sudden changes in temperature without shattering. However, Pyrex does have a maximum recommended temperature of about 420°F (214°C).

It isn’t safe to put cold Pyrex into a microwave because it can shatter when heated suddenly. Even if you’re careful about following the manufacturer’s instructions for heating cold Pyrex, there’s still a chance that you’ll end up with a broken glass or chipped pieces of your favorite bowl or casserole dish.

Microwave Safe Pyrex Bakeware and Food Storage Set

The set is made from durable and high-quality tempered glass and is safe for the freezer, microwave, and preheated oven.

What Are the Best Practices for Microwaving Cold Glass?

There are a few best practices to follow when microwaving cold glass.

  • First, make sure the glass is microwave-safe.
  • Second, place the glass on a microwave-safe plate or surface.
  • Third, microwave the glass for a short time, such as 15-30 seconds, and check it frequently to ensure it doesn’t get too hot.
  • Finally, allow the glass to cool before handling it.

What Are the Risks Associated with Microwaving Cold Glass?

There are several risks associated with microwaving cold glass. The first is that it can cause the glass to explode or shatter, which can be dangerous if the glass shatters in your microwave. The second is that it could cause the glass to crack or break. This is less likely than explosion or shattering, but still possible.

The safest way to microwave cold glass is to bring it to room temperature first. This can take quite some time, depending on where you live and how cold it is outside.

How Can I Avoid Microwaving Cold Glass?

Microwaves heat food by exciting the water molecules within it. The movement of these excited molecules, in turn, causes nearby food molecules to vibrate and generate heat.

Some glassware has a thin layer of metal on its surface that acts as an antenna for the microwave energy and heats up first, causing the glass to shatter.

To avoid microwaving cold glass, use only microwave-safe containers marked with a circular logo containing an image of a wave or a word such as “microwave” or “oven safe.”

Many manufacturers make containers specifically designed for microwave cooking with either a raised symbol or textured material on the bottom of the container or both to indicate safe usage.

You can also make your microwave-safe container by placing wax paper between two pieces of ceramic dinnerware; however, this may not work well for all types of glassware.

Care Tips to Microwave Cold Glass

Here are the care tips you can follow when microwaving cold glass: 

  • When microwaving cold glass, start with shorter intervals and increase as needed.
  • Be sure to rotate the dish during cooking to ensure even heating.
  • Take extra care when removing hot glass from the microwave. Use oven mitts or a towel to protect your hands.
  • Allow hot glass to cool slightly before handling or cleaning.
  • Never put cold glass in a hot microwave. This can cause the glass to break.


In the end, we hope this guide, “Can You Microwave Cold Glass,” is helpful for you. We recommend using a microwave-safe container to avoid the risk of glass breakage. This will help prevent any potential hazards. In addition, you can also microwave glassware with food inside it.

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