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Can You Microwave Cold Pyrex?

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Though it has been claimed by the manufacturers that you can microwave Pyrex as well as it being freezer safe. But, can you microwave cold Pyrex that has just been in the freezer?

If you microwave cold Pyrex by transferring it from the freezer or refrigerator to the microwave, then it may crack or shatter due to abrupt change in temperature.

Pyrex is thicker and harder glass than the glass used in other kitchen-wares. When cold Pyrex is directly put into a pre-heated microwave, then due to the change of temperature, the temperature of its different elements will change at different speeds. 

This uneven exchange in temperature can give a shock to the Pyrex glass and it will crack or shatter within a few minutes. Microwaving cold Pyrex does not have to be complicating, so let’s discuss the dos and don’ts of heating cold Pyrex in the microwave. 

Is it safe to microwave cold Pyrex?

Through a press release, the manufacturers of Pyrex have assured that Pyrex is microwave safe can be used safely. However, you will have to follow a few rules. 

The type of glass used in Pyrex kitchen cookwares is thicker and harder than the glass used by other brands in making their glassware.

You will have to be careful while heating or cooking food in Pyrex ware in a microwave, as the electromagnetic kitchen appliance is not specifically mentioned in this regard on their official website.

According to them, Pyrex glassware can crack or shatter when there is an abrupt change in the temperature of its surroundings.

Therefore, it may not be safe to microwave cold Pyrex as it can crack or shatter due to the change in temperature of Pyrex and the microwave enclosure. It may not bear the shock of this rapid temperature fluctuation.

In fact, Pyrex glass is safe when used either in refrigerator or microwave. The difficulty arrises if it is transitioned from a colder environment to the hotter one too quickly, then it may not handle the change in temperatures. 

It will explode into pieces if you directly put cold Pyrex into a high heat microwave after removing it from the fridge or freezer.

Similarly, when hot Pyrex glassware from the microwave is placed in the fridge or freezer, the glassware cracks or shatters due to the thermal shock caused by the rapid decrease in the temperature.

Can you microwave cold Pyrex?

Does cold Pyrex break in microwave?

Yes, cold Pyrex will break in the microwave as the glass used in making this glassware cannot resist rapid change in temperatures. It is harder and thicker than the glass used by other brands of cooking glassware.

The main reason behind the breaking of cold Pyrex in the microwave is that it is made of borosilicate glass. Even though glass is safe to use in the microwave, there are a few precautions that must be followed.

When the temperature of glass changes rapidly, it experiences a thermodynamic reaction. The thermal shock is the stress produced in a material because of abrupt changes in its temperature.

When a cold bowl of Pyrex is heated rapidly in the microwave, then its parts will contract or expand at different rates which will cause stress to the glasslike material. The structure of the bowl will not be able to handle this much stress, therefore it will break or explode.

You can avoid the shattering effect of microwave heat on the cold Pyrex bowl by changing its temperature mindfully. Gradually raise the temperature by introducing low power level in the beginning, then incrementally working up the heat over the course of a few minutes.

Cold Pyrex glassware will fail to resist the immediate increase in temperature if it is taken out of the fridge and put directly into a preheated microwave. It will break due to an instant transition in temperatures.

How do you microwave cold Pyrex?

When you have to microwave cold Pyrex glassware, then instead of putting it directly from the fridge to the microwave, it’s recommended to allow the chilled container to come up to room temperature

According to the USDA temperature danger zone guidelines, perishable food items that needs to be cooked, reheated, refrigerated or frozen within 2 hours. As long as the food is cooked or stored within 2 hours of exposure to the temperature danger zone, then it is considered safe to eat.

Therefore, you can either put the cold pyrex on your kitchen countertop for 15 minutes or so to normalize its temperature, or put it in a bowl of slightly hot water for this same purpose. Afterwards, you can microwave it when its temperature comes to room temperature.

In case you put it directly into the preheated microwave, then it can crack or shatter due to sudden changes in the temperature of the Pyrex ware and the microwave. The safest way to microwave a cold Pyrex is to bring its temperature to room temperature before putting it into a high heat microwave.

Tips to Microwave Cold Pyrex

Microwaving cold Pyrex can be quite dangerous and is not advised. Instead of sticking chilled Pyrex into a high heat microwave, utilize the methods to gradually increase the surface temperature of the cookware.

To microwave cold Pyrex glassware you will have to follow the following tips:

  • Take the Pyrex glassware out of the fridge or freezer.
  • Put it on the countertop of the kitchen to allow its temperature to increase to the room temperature of the kitchen.
  • To expedite the process, take a larger container than the Pyrex ware.
  • Fill a large pot with water so that your Pyrex can be placed in the water.
  • Put the container in the sink and run warm water for a couple minutes, or place the container on the stove to warm up the water. Slightly heat the water and not boil it.
  • Gradually warm up the water with the Pyrex ware inside it so that its temperature can be increased faster to room temperature.
  • Within a few minutes your cold Pyrex container will be ready to thoroughly heat in the microwave.

Please note that you have to increase the temperature of the Pyrex ware, not of the contents in it. Cold Pyrex is the danger, not the temperature of the contents inside the container.

Microwaving Cold Pyrex: Final Thoughts

In conclusion, is not safe to microwave cold Pyrex. You will have to handle the chilled glassware carefully if you have to microwave cold Pyrex as discussed in this write-up.

In fact, Pyrex glassware is made of glass that is harder and thicker than the glass used by other brands for glasslike cookware. Though it has been assured by the makers of Pyrex glassware that it is microwave and freezer safe, still they have suggested manufacturer recommended guidelines to use them carefully.

According to the usage instructions recommended by Pyrex:

  • Before putting in cold Pyrex dish into a microwave, always bring the glassware to room temperature.
  • Pyrex glassware should never be used on the stove, BBQ grill, toaster oven, or electric burner or under the broiler
  • The bottom of the Pyrex glassware should be covered with some liquid. Microwaving food that can release liquid in the form of juice of the food, moisture from frozen food or melted fat, etc. It will minimize the risk of breaking the glassware due to sudden changes in the temperature.
  • Never add any liquid once the Pyrex glassware is hot as this can cause the cookware to break due to sudden changes in temperature.

Be careful when you microwave cold Pyrex and follow these precautions to avoid breaking, cracking or shattering your glassware in the kitchen appliance.