Can Pyrex Go in The Microwave?

*This post may contain affiliate links. Please see my disclosure to learn more.

You may want to consider a few things before putting Pyrex in the microwave. 

Pyrex glassware and kitchenware are ubiquitous and extremely convenient. So, naturally, one might want to use it directly in the microwave to save time and avoid piling up additional containers in the dishwasher. 

But can Pyrex go in the microwave? Yes, Pyrex is microwave-safe and can be used to heat food directly in the microwave. However, you should double-check the labeling on the bottom to confirm its safety and you should never put cold Pyrex in the microwave because it may shatter due to thermal shock.

How is this material good and bad for microwaves? Read below to learn more!

Pyrex And Microwaves

Pyrex has been around since the early 1900s. It has revolutionized glassware and kitchenware and its products can be found around the world.

Made from low-thermal-expansion borosilicate glass, Pyrex produces sturdy glass and ceramic products that have wide applications in storage and heating

While you can normally use any type of microwave-safe Pyrex container, you should always first confirm the labeling of the product.

Check the bottom of the container to see all the relevant labeling. Also, you may check their website for more safety information. 

Pyrex produces many microwave-safe products that you can use even with the lid on. But keep in mind that not every container is built to be used in microwaves or with heat. 

Microwaves are incompatible with any type of foil and can cause serious sparking issues. The way microwaves work is by using a high-powered magnetron that produces focused microwaves that bounce off the walls of the chamber inside.

The waves are majorly absorbed by water and fat molecules, thereby transferring energy into them. This excites the molecules which then create friction and heat. 

This is why microwaves can penetrate deep into the food and heat it, both, from within and superficially. 

In comparison, an oven would first superficially heat food and transfer heat from the outside in. 

 To be rated as microwave-safe, food containers need to overcome two issues:

  1. They need to handle heat and steam.
  2. They must not react to microwaves in any way.

Both problems are relatively easy to solve. For example, you can always heat food with the lid open, which will release steam without any buildup. The second problem can be tackled by using microwave-safe materials!

However, with Pyrex, there is another point to consider: the fragility of glass.

Glass And Microwaves – A Dangerous Combination?

Modern glass manufacturing technology is now advanced enough to produce sturdy containers that are both microwave safe and heatproof. But no matter how advanced a glass product is, it will always have a few inherent flaws.

For example, when heating food at room temperature, Pyrex containers will be able to withstand heat very easily. However, these containers may not fare well when you heat them directly from the freezer.

This isn’t a limitation of Pyrex! It’s a common occurrence in glass containers. 

This phenomenon is called “thermal shock” where sudden temperature changes can cause mechanical stress on the surface of the glass, which causes it to eventually crack!

Again, this is why you need to check the labeling of the container you are investing in.

Pyrex offers a range of products that can somewhat overcome thermal shock but you should still try to NOT heat frozen food in glass containers. 

Microwaves can reach up to 212°F. But the thing with thermal shock is that it mostly occurs when the temperature change is around 50°F

While this rate may vary from one appliance to another, it is best that you only choose Pyrex’s line of microwave-safe products for the best experience. 

Pyrex claims that its specialized glass products can withstand extreme temperatures, ranging from -40°F to 390°F.

This means that you may be able to easily heat frozen food in the same containers—but again, a little caution will go a long way!

Also, another thing to keep in mind is the steam generated from the food while it heats.

Remember, microwaves can penetrate materials very easily so they can be readily absorbed by water and fat molecules in the food. If the container is airtight, then you may want to opt for a glass container that accounts for steam.

Pyrex similarly offers a lot of different products that have steam outlets that allow gasses to escape. This type of design regulates internal pressure which may even help the food be less soggy. 

Keep in mind that as you increase the moisture content within the container, the food will either become too wet or crumbly. 

To overcome this problem, you can try heating the food with the lid open.

If you are unable to open the lid or if the container is frozen rock solid, then instead of directly thawing or heating it in the microwave, we suggest that you thaw the container overnight in the fridge.

This technique is perfect for every type of food container as it will greatly minimize the overall stress that is put on the glass but if you can’t wait that long then heating the container incrementally may help avoid disaster.

Start with the thaw setting and then slowly increase the power output of the microwave until it is operating at full power.

This strategy will reduce the overall thermal stress on the container and will also help you heat food more efficiently. 

The Right Way To Heat Food In Pyrex

Here are a few steps to properly microwave food in Pyrex:

  • Begin by storing food using the right storage protocols. For example, never overfill a Pyrex container and leave enough headroom for the food to heat without spilling. Also, make sure that you properly seal the container as indicated by the manufacturer.
  • Store Pyrex containers in the fridge at 40°F. You may also freeze them as indicated in the labeling below. Typically, Pyrex containers can withstand freezing temperatures so they will be suitable for temperatures as low as 0F – which is also the USDA recommended temperature for food storage. 
  • Once you’re ready to heat food, simply move out the contents onto a microwave-safe plate OR put the Pyrex container into the microwave directly from the fridge. You may want to thaw the container overnight when heating frozen food from the freezer.
  • Check the indications on the packaging you received with the container or you can also check out Pyrex’s website for more information on how to use and properly heat your specific container. It would also be a good idea to remove any reactive materials like foil or utensils before heating. 
  • Please be mindful of the container and its contents when heated. The container may not look hot but it may be heated enough to cause minor injuries or accidents. Always use heatproof gloves or a cloth to remove the Pyrex container from the microwave.
  • You can also leave the food in the microwave chamber for a while before taking it out. Take out the container after 3-5 minutes for warm food and a safe-to-handle container!

How To Pick The Best Storage Container

Most people buy the first container or glassware they see and while this strategy may work most of the time, in certain situations, you might benefit more if you do a little research beforehand. 

For example, if you want a Pyrex product that you can easily use in the microwave then we suggest that you look into a 6-piece glass storage container set.

These containers are great for everyday use and are rated for both ovens and high-heat microwaves and the lids are microwave safe too! 

If you are looking for something bigger and suitable for cooking then you can go with a 2-quart Pyrex Easy Grab Glass Dish that can easily withstand extreme temperatures and is great for a variety of recipes. 

It’s made from the same strengthened glass that Pyrex is known for and is also completely safe in every aspect.

However, to ensure the longevity of this product, we recommend that you follow our guide and tips in this article for long-term use.

Finally, for bakeware, we recommend that you check out the Pyrex 3 Piece Glass Mixing Bowl Set which includes a range of different sized and microwave-safe bowls for everyday use. 

There are plenty of other options that you can go for as well. Just remember, follow the indications listed by the manufacturer and you should be able to get the most out of Pyrex for years! 

Heating Bakeware And Other Glass Dishes

Bakeware and glass dishes will likely fare better than enclosed containers. Pyrex offers a range of different bakeware, roasters, and glass dishes that you can freely use with your microwave. 

Most of these glass products are built with high temperatures in mind so you will easily get away with using them in the microwave too. 

However, even with these lid-less glass containers, the same rules of heating apply. Keep in mind that glass, like every other material on earth, is bound by the laws of physics, no matter how well they are manufactured

Unless specified by the brand, you should try not to rapidly heat frozen glass containers and vice versa. 

Bakeware is typically a popular choice for ovens and microwaves which means that you can easily cook and reheat food directly in the container.

Of course, you would have to remove any foil or metal-covered lids before microwaving the containers. 

Wondering what would happen if you accidentally left a metal and glass lid in the microwave? Well, not much.

Interestingly, microwaves only affect crumpled-up pieces or large masses of foil or metal.

This means that in some cases objects with a thick and smooth surface may be able to deflect microwaves. Think about it, the walls inside the microwave are made of metal!

The reason why the entire unit doesn’t go up in flames is that there are no pointy or uneven parts in the walls.

Everything is smooth and uniform, which allows the microwaves to be deflected around the chamber instead of causing a buildup of current. 

So, unless the lid of your Pyrex container has an awkward design or uneven metallic pieces on the lid, you may be able to easily use the lid in the microwave as well

But of course, we highly recommend that you check the manual of your bakeware or glass containers before using them in the microwave

Tips And Tricks

Here are some great tips and tricks for using Pyrex in the microwave:

  • Go for a container with built-in steam outlets that can easily disperse excess heat from the food. Pyrex designs multiple microwave-safe products so you can choose one that best fits your needs.
  • Try heating liquids with the lid partially on. This is to protect the walls of the microwave from splashes. As the liquid and contents heat, they may form bubbles or heat pockets that may rapidly expand and cause a mess. The lid will take care of this problem by creating a shield. 
  • Always handle Pyrex containers with care and caution. Microwaves are notorious for heating and at times, overheating food and containers. Use protective gloves and put down the heated glass container softly over the counter. Any sudden movements may cause cracks and break the container!
  • Try to avoid rapidly cooling Pyrex containers. As soon as you are done heating the food, take out the contents and wait until the container is at or around room temperature. Exposing the container to heat and then cool temperatures may cause micro-cracks or visible breakage. 
  • Similarly, avoid adding hot liquid to Pyrex containers and never overheat liquid-based foods like soup or sauces in the microwave. Pay attention to the cooking or heating time and follow all the necessary safety protocols to avoid any accident. 
  • When using a high-powered and high-heat microwave, start with the intermediate setting and then increase the power setting as needed. This is great for 2 reasons: 1.) it will reduce the number of cold spots in the food and 2.) it will ensure the safety of your appliance and the Pyrex too.

Related Questions

The dos and don’ts of microwaves may be a bit confusing but with the right product and our guide, you will be able to use Pyrex containers without fail! 

Now that you know how to use Pyrex in microwaves, here are some related questions!

Are all Pyrex lids microwave-safe?

Generally speaking, Pyrex products are designed to be microwave friendly but if you have an old product at home then you might want to check the bottom of the container for proper labeling.

The labeling will help you determine if your specific product is microwave or oven safe.

You can also search online for more information on your specific glassware. If you have doubts about the safety of your Pyrex then we highly recommend not using it with the microwave. 

Should you heat and then refreeze Pyrex?

Once stored food is heated, it should be consumed within the same day. The reason for this is that reheating and storing food repeatedly may compromise its quality and safety

While it is possible to place reheated food in Pyrex in the fridge, we would suggest that you wait until at least the container is at room temperature before moving it to the freezer. 

Which microwave setting is the best for heating Pyrex?

Room temperature Pyrex can be heated at full power using any type of microwave.

For freezer-stored Pyrex, always start at the medium setting and set the timer as required. You can check the Pyrex and food after 2-3 minutes to see if it is heating as required

Add 1-2 minutes of heating time to the microwave until the food is adequately warm and ready!

Up Next: Lemon Dump Cake

Leave a Reply

Your email address will not be published. Required fields are marked *