Can you put cold glass in the oven?

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When it comes to handling cold glass, you will need to use a few precautionary measures to keep the glass and yourself safe. Cold glass is known to shatter when it is subjected to extreme temperature differences, but there are a few exceptions to this case!

Can you put cold glass in the oven? Most types of glass are made from inferior-quality materials that result in glass that will likely shatter when it is moved from the freezer into the oven. But if you use borosilicate or fortified glass like Pyrex, then you might be able to get away with using cold glass in the oven.

Read below to learn more about why glass shatters, how you can prevent it from shattering, and some tips and tricks for handling cold glass. 

Glass and Heat Transference 

Glass has been the go-to material for making all sorts of containers but it has always been a brittle material that requires the lightest of hands. 

Typical glass is made from sand, soda ash, and limestone.

When these materials are superheated and mixed, they create a pliable soup that can be poured into any mold. When the mold hardens, glass is formed.

This type of glass is suitable for all-purpose use, but cold glass is inherently brittle because glass is a poor conductor of heat.

Unlike other materials like metal, glass does not transfer heat efficiently – and because of this, when heat is applied to it, it is put under stress.

Normally, if you pour hot water into any type of glass at room temperature, nothing will happen – or at least you won’t see anything happen.

But if you take a look at the glass under the microscope, you will notice small cracks forming around the surface.

These cracks are caused by thermal stress.

In a nutshell thermal stress is the degree to how much stress the glass can take before it cracks and breaks.

Another way to look at this is in terms of thermal resistance which can be defined as the ability of the glass to take on varying temperature changes. 

For example, a glass with low thermal resistance will likely break when it is stored in the freezer and then put out in a hot environment.

Some types of glass made from inferior quality materials may even shatter when frozen, even if they are gently put over a counter. 

See, when you freeze a glass and then pour hot liquid inside it, the inside of the glass will quickly begin to heat up but the exterior will remain relatively cooler.

The reason for this goes back to the glass being a bad conductor of heat.

The superficial layer inside the glass which is surrounded by extremely hot water will begin to take on more stress than the outside.

This will cause uneven thermal expansion – and soon enough, micro-cracks will begin to form. 

This is when things can get dangerous. If the glass has already been exposed to stress in the past or if the temperature difference is significant, the glass will likely shatter before you even fill it up to the brim with hot water.

So, is glass doomed to forever be a flawed material that can’t be used in the kitchen? Of course not!

Keeping reading to learn more about the clever ways manufacturers make glass more durable.

Borosilicate Glass

Not all glass is made the same! 

Although most of the ingredients used in glass making are the same, glass makers found out decades ago that if they changed a few techniques and added a few compounds to the glass, they could significantly improve its thermal expansion capabilities, which makes the glass much more durable.

This is where borosilicate glass comes in. Borosilicate glass is made by melting sand with boron trioxide.

This process limits the resulting glass’s ability to expand when exposed to varying temperatures. 

Borosilicate glass is also quite common, and chances are that you might already own it! Pyrex is a great example of a brand that is based on the discovery of borosilicate glass. 

Ever wondered why Pyrex products can handle high heat and even cold temperatures so effectively?

Well, that is because this glass cookware is made from borosilicate glass and advanced manufacturing techniques that give it very high thermal resistance. 

If we are talking exclusively about heating food, then you can easily heat food to 400F-425F. But some borosilicate glass can even be put in the freezer at 0F and then directly in a preheated oven at 400F without it shattering!

The best way to check if your glass cookware can handle thermal stress is by looking at the manufacturer’s website or the back of the packaging. 

Pyrex, for example, has detailed information about all its products, which includes safety and precautionary information. Please note that while most borosilicate glass can handle high heat and cold temperatures, you should try to reduce the stress put on the glass to maintain its longevity.

The reason for this is simple: glass is glass, and no matter how you prepare it, it will always be inferior to other sturdier materials.

Even in the case of borosilicate glass, if you repeatedly freeze and heat the glass, this will eventually cause the structure of the glass to lose its integrity. 

In other words, it will jeopardize the thermal qualities of the glass and will make it risker for future use!

How to Handle Glass in the Fridge and Oven – Tips and Steps

Now that you know which type of glass to use for freezing and cooking, let’s take a look at some of the ways that you can use glass to ensure its safety. 

Prerequisite) Preheat the oven to 400F. Please check the thermal limits printed on the back of the cookware. If you have lost the leaflet then simply check the manufacturer’s website for the temperature limits of the glass.

Step 1) Assemble all the ingredients in the glass cookware. It’s better than you marinate meat in the glass so that everything cools down evenly. 

Step 2) After 4-8 hours at 0F, the glass will completely freeze. This is where you need to be extra careful. Place a soft towel over the counter and then gently put the cold glass cookware over it. 

Step 3) You can now either allow the Pyrex and ingredients to thaw for 1-2 hours, or you can also put the glass directly in the oven

Step 4) Gently lift the glass and softly place it over the oven rack. Do not drop, tap, or slam the glass cookware in the heated oven. 

Step 5) Cook the food as intended. 

Step 6) Take out the hot glassware from the oven and put it over a thick but soft counter mat. You can also use a towel for this. Do not use a wet towel!

Step 7) Let the cookware cool down for 5-10 minutes and then move the food around. Remember, if you start to poke the base of the hot glass with a utensil, then you might just induce micro-cracks that can damage the structural integrity of the cookware. Let it cool down before moving food around!

Step 8) Once the cookware has cooled down completely, wash it as instructed by the manufacturer. 

Pro Tip) While borosilicate glass is suitable for all types of cooking methods, you should double-check the instructions provided by the manufacturer when broiling food. Broiling involves heating food at very high temperatures, sometimes exceeding 450F-500F. 

Be extremely careful when using cold glass for broiling and ensure all the necessary safety measures even when picking up or putting down the glass on cool surfaces. 

Related Questions 

Cold glass in the oven might not be a great idea when using typical glass, but you might get away from using it if you use borosilicate glass that is designed to withstand extreme temperature differences. 

Now that you know how to (and what type of) glass to use in both the freezer and oven, it’s time to look at some related questions:

Can borosilicate glass be used in the microwave?

Yes, borosilicate glass is safe to use in the microwave. But for the best experience, we highly recommend that you check the manufacturer’s instructions to be sure of the limitations of the glass. 

Microwaves use high-powered microwave energy to heat food. Some of these waves might be absorbed by the glass which can heat it. Always use all the necessary safety precautions when dealing with glass cookware.

Can you put boiling water in a cold glass? 

Pouring boiling water into a cold glass may not be suitable for glasses made from inferior-quality materials. But if you are using thicker and heavier glass, then pouring hot water in it might not result in any damage. As with every other type of glass, always check the instructions provided by the manufacturer for the best results. 

Can you put cold glass in the oven and then back in the freezer?

We do not recommend that you put hot glass back in the freezer. While borosilicate glass might be able to handle the sudden temperature change, the hot glass may end up damaging the inside of your freezer. Always wait 30 minutes to an hour before putting the hot glass back in the freezer. 

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