March 29

Is Pyrex Microwave-Safe? Doing it Safely

Written by: Dolly

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It's late, you've just gotten home from work, and you're exhausted. Your next move is throwing those day-old leftovers into the microwave and eating on the couch, while zoning out to the some reality TV. 

We've all been there.

Pyrex is quick, easy, and simple. It's stain-resistant, plastic-free, and crazy durable.

Although it is microwave safe in most situations, there are a few things to be aware of before your next late-night leftovers dive.

Let's take a look. 

What is Pyrex Anyway?

pyrex-measuring-cup

Pyrex is a beloved brand that uses borosilicate glass to make hardy, durable, and handy products, such as tubs for food storage, bowls, and liquid measuring cups.

This special combination of boric oxide and silica creates the superhero of all glass products.

However, as with any glassware, there are always risks. Glass is prone to cracking or exploding when exposed to sudden and drastic temperature changes.

Sadly, when Pyrex cracks, the manufacturer recommends tossing it immediately, as it is now at risk for explosion. And nobody wants that.

To avoid explosions, cracks, or shattering, we recommend you take the following precautions.

Is it Safe to Microwave Pyrex?

small-microwave-in-kitchen

Yes! Glass and ceramic are often considered to be the best, microwaveable materials. With Pyrex, you don't have to worry about BPA exposure or plastic melting and leaking into your food.

That being said, there are a few situations where it is not safe to microwave your Pyrex.

Here are a few things to remember before you reheat your leftovers.


How long can you Safely microwave Pyrex?

Fun fact, each piece of Pyrex glassware is tested before it's introduced into the market. Perhaps tested is too gentle a word; Pyrex's rigorous rounds of testing usually last around 1,000 hours!

Now, I can't imagine you'll be putting your leftovers in the microwave for 1,000 hours anytime soon, so you should have nothing to worry about, no matter how long you might need to microwave your pyrex for. 


How can you tell if Pyrex is Microwave-Safe?

pie-crust

Pyrex has been on top of the game for years now, so it should come as no surprise that all of their glass inventory is microwave-safe. All of it!

That being said, it never hurts to test your Pyrex if you aren't sure. Fill it up, throw it in the microwave, and watch it spin for a minute or less.

If your glassware is piping hot to the touch after, so much so that it may burn you, then it may be best to keep it out of the microwave.


Is it Safe to Microwave Cold Pyrex?

No, not necessarily. If you remove your Pyrex from the fridge or freezer, the sudden temperature change in the microwave could cause an explosion, crack, or fissure in the glass.


Is it Possible for Cold Pyrex to Explode in the Microwave?

whipped frosting

Unfortunately, yes. It is possible for cold Pyrex to explode in the microwave due to thermal expansion. All glass products are subject to the laws of thermal expansion.

When exposed to drastic temperature changes or extreme heat, glass molecules will expand and potentially explode.

For example, placing a burning hot dish onto a cold surface may cause it to crack or burst. The opposite can be true as well.

To avoid a potentially dangerous situation, read the following tips and tricks:


Tips for Microwaving Cold Pyrex

  • Read the instruction manual. Certain Pyrex collaborations are designed to withstand going from a cold fridge to a microwave. Others not so much.
  • Let Pyrex taken from the refrigerator or freezer rest and raise to room temperature before microwaving for long periods of time.
  • If you're short on time, try to microwave the Pyrex in segments. These shorter periods of time on a lower heat will greatly decrease the chances of thermal expansion.
  • Remember to ease the transition from cold to hot or hot to cold as best you can.


Can Pyrex Go From Freezer to Microwave?

cherries-in-glass

Not safely. Pyrex is made of glass, an incredibly durable material, but it's not perfect.

When it's exposed to extreme and drastic temperatures in a short period of time, the molecules will expand and cause the glass to crack or burst.

Placing an ice-cold Pyrex from the freezer into a microwave may result in an explosion or cracking due to thermal shock.


Can You Microwave Pyrex Lids?

Yes! Pyrex has two types of lids for its kitchenware: plastic lids and matching glass lids.


Glass Lids

The matching glass lids follow the same rules as the glass container.

Although they're made out of the same hardy glass, they are still susceptible to cracking or shattering when exposed to extreme temperature changes. 

However, when handled properly, glass Pyrex lids can be used both in the microwave and oven.


Plastic Lids

Pyrex is a very thoughtful brand, so their plastic lids are BPA-free. This means that they are safe to microwave!

However, the one drawback of plastic lids is that they are not as heat-resistant as their glass counterparts.

Unfortunately, they cannot be used in the oven due to the high heat and risk of melting.


What Temperatures are Safe For Pyrex?

casserole

Pyrex, thanks to its mixture of boric oxide and silica sand, is incredibly heat-resistant. In fact, its melting point is 1510°F, so I think it's safe to say your container won't be melting anytime soon.

But let's scale it down. Pyrex can safely withstand temperatures ranging from -104°F to 572°F, so it can and will cover all of your cooking needs.


Can Pyrex Go in the Oven?

baking-in-oven

In most cases, yes, Pyrex is absolutely safe to put in the oven. However, there are a few things to be wary of before baking with your Pyrex:

  • Preheat the oven BEFORE placing your Pyrex into it.
  • Do not put Pyrex under the broiler.
  • If you are cooking something that may release liquid (such as fat, juices, or excess water), put a small amount of liquid in the bottom of the Pyrex before placing it in the oven.
  • When you take the hot Pyrex out of the oven, do not put it onto a wet, cool, or metal surface. Place it on an oven mitt, hot pad, or a wooden rack instead.


These tips and tricks are necessary to prevent your Pyrex from cracking, shattering, or exploding in the oven from thermal shock.


Conclusion

Pyrex is absolutely microwave-safe, but there are a few situations you want to avoid.

So long as you keep in mind those drastic temperature shifts and follow the provided instructions, you and your Pyrex should have a long and happy life together.

Thanks for reading and please reach out if you have any further questions...we are here to help.

Dolly


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About the author

Dolly is a student at Goldsmiths, University of London and an avid cook. After managing a miniature organic farm for a year, she fell in love with the art of cooking and the taste of homegrown greens. Dolly first became plant-based eight years ago, and she is now a full-blown vegan; her plant-based journey has made her creative and experimental in the kitchen. If she’s not writing or cooking, Dolly can be found on her front porch, strumming her guitar and singing for anyone who will listen.

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