A set up Pyrex dishes and bowls on a brown table

We’ve all been there. Walked into the kitchen to heat up some leftovers, spaced out, and grabbed the closest Pyrex dish. But wait, can you microwave Pyrex?

You’re in luck, we have the answer to that question. You can, in fact, microwave Pyrex. It’s completely safe and a great heat resistant dish to use in the microwave. There are some precautions to take though, especially when transferring cold or frozen Pyrex dishes to the microwave.

We give you all the details below on microwaving Pyrex!

Read on to learn more!

What is Pyrex?

Pyrex is a type of glass that is well known for its resistance to thermal shock. This makes it ideal for kitchen use, as it can handle sudden changes in temperature without breaking or suddenly exploding. Pyrex is also non-porous, meaning it doesn’t absorb liquids or flavors – making it a popular choice for storing food.

The secret lies in the types of glass used to make Pyrex. Borosilicate glass is typically used in laboratory settings, while soda lime glass is used for kitchenware. Common glass is made from silicate and expands when heated, causing breakages.

  • Soda lime glass is a cheaper alternative to borosilicate. Original Pyrex was made with nothing but borosilicate, but today lime glass is used exclusively for kitchenware.

Pyrex can withstand temperatures as high as 425 degrees Fahrenheit! It probably won’t get that hot in the microwave, but if you use it in the oven, that will come in handy!

Pyrex has a specific chemical composition that gives it its brand name:

  • Silicon – 81%
  • Sodium – 4.0%
  • Aluminum – 2.0%
  • Boron – 13%
  • Potassium – 0.5%

Can You Microwave Pyrex?

You can microwave Pyrex! The USDA Food Safety and Inspection Service has deemed Pyrex as microwave safe.

There are some things you need to know though!

  • Pyrex is made of either borosilicate or soda lime glass and is heat resistant up to 425 degrees Fahrenheit, making it a good option for microwaving.
  • When microwaving Pyrex, it’s best to use smaller dishes. Microwaves do not cook food as evenly as ovens. Use the smaller flat Pyrex dishes to ensure your food cook all throughout!
  • You should avoid using high power settings or heating food for an extended period of time in a Pyrex dish. This will also allow the food to cook more evenly and thoroughly!
  • There is also the possibility that the Pyrex dish could break if it is frozen prior to being put in the microwave. Modern-day Pyrex made from lime glass is less resistant to extreme temperature changes.

Is There a Pyrex Dish Better for Microwaving?

All Pyrex dishes are microwave-safe and suitable to use, however, some Pyrex dishes will work better than others in the microwave.

Microwaves work by producing high temperatures and fast vibrating frequencies that penetrate the top layer of food, leaving the middle part still cool and uncooked.

To work around this issue, it’s best to use smaller Pyrex dishes that you can create an even layer in so food cooks all the way through. An example is this 2-cup Round Dish

The Pyrex Microwave Safe Symbol

The best way to determine whether a material is microwave safe or not is look for the symbol or some indication that it’s safe. On many containers you’ll see a symbol of a microwave with wavy lines, like below.

On Pyrex dishes you may not see this symbol.

Typically, the words “Microwave Safe” are indented in the glass on the bottom of the dish.

How to Stop Pyrex From Exploding

The original Pyrex made exclusively from borosilicate glass was very thermal shock resistant. Today’s Pyrex made from soda lime glass is not.

Thermal shock refers to the process that the component experiences suddenly changed thermal stresses and strains of large magnitude when the heat flux and component temperature gradient change abruptly. Thermal shock produces cracks as a result of rapid…temperature change.

science direct.com

Sudden changes in temperature can cause your Pyrex dish to crack, sometimes through an explosive force.

Follow these tips:

  • Always follow the manufacturer’s guidelines. You can find Pyrex safety info here.
  • Always let a frozen or cold Pyrex dish thaw to room temperature before putting it in the microwave.
  • Be careful to not drop your Pyrex dish or bump it against anything. It can cause cracks.
  • Stop using if there are cracks in the Pyrex dish.

Potential Health Concerns Using Pyrex

At this moment, there are no noted health risks with using modern day Pyrex.

I did run across a few resources discussing lead toxicity in vintage, or pre-1979, Pyrex. It lives in the outside paint on the dish. I would recommend checking it out if you have health concerns and using vintage Pyrex!

Last Minute Safety Tips for Microwaving Pyrex

Here are a few last-minute safety tips for having the best experience when microwaving your Pyrex!

  1. Don’t pour cold liquids into a hot Pyrex dish and vice versa.
  2. Don’t place a Pyrex dish directly on a heat source, such as stove eyes.
  3. Don’t microwave your Pyrex dish empty. This can lead to cracking or possibly an explosion.

Frequently Asked Questions

Can you Microwave Pyrex With a Lid?

All Pyrex lids are BPA (Bisphenol A) free, whether they are made of plastic, silicone, or glass, and considered microwave safe. Because of this, food is safe from leeching chemicals. The fact that the lids are microwave safe means they will not warp or melt in the microwave. Pyrex containers and Pyrex lids can be used interchangeably as long as the size of the lid is appropriate for the size of the container.

Can You Put Pyrex in the Oven?

Yes, you can put Pyrex in the Oven! But follow these tips.

  1. Before placing your Pyrex dishware in the oven, add a small amount of water to the bottom, completely covering it. This helps to minimize the effect from temperature changes.
  2. Preheat your oven BEFORE you put Pyrex in it, to avoid directly exposing it to the heating element in the oven.
  3. Unless specifically noted, Pyrex lids are not designed to be used in the oven, otherwise they will melt.

Can Pyrex go in the Dishwasher?

Yes, Pyrex can go in the Dishwasher! If possible, place the Pyrex dishes on the top rack away from the heating source of the dishwasher. This goes for Pyrex dishware and Pyrex lids!

Can You Microwave Pyrex From the Freezer?

Pyrex is a versatile dish. You can safely use it to store food in the refrigerator or freezer. You don’t have to worry about using it in the oven or the microwave. However, you do need to take precautions when using a frozen Pyrex dish in the microwave.

Pyrex is made of borosilicate or soda lime glass, which can withstand high temperatures and therefore can be safely microwaved. However, thermal shock can occur when the Pyrex is subjected to a dramatic change in temperature, such as going from the freezer to the microwave. To avoid thermal shock, it’s important to thaw the Pyrex at room temperature before microwaving. Otherwise, the sudden change in temperature could cause the Pyrex to crack or shatter.

Pyrex, themselves, even recommend this bit of advice here, under Pyrex Safety and Usage Instructions.

Final Answer for, Can you Microwave Pyrex?

Concerning modern-day Pyrex, I won’t be giving it up. I feel comfortable using it in the microwave to heat up my food both for my health and safely microwaving my food. Follow the safety precautions and tips given in this blog post, and you should be able to have your Pyrex last you a lifetime.

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