Whether you want to store food or you want a chilled glass for a cool beverage, you’re probably wondering if you can put glass in the freezer.
Glass can be put in the freezer as long as you are careful about thermal shock. Don’t rapidly heat the glass or rapidly cool it. Allow the glass to reach room temperature before placing it in the freezer. However, food stored in glass containers is more likely to get freezer burned compared to airtight freezer bags.
Below we have some more tips about storing glass in the freezer and for how you can avoid thermal shock, which can cause glass containers to shatter.
Putting Glass in a Freezer
There are a couple of things to keep in mind when putting glass in the freezer. The first is thermal shock and the second is the type of container.
First and foremost, you need to be aware of thermal shock. Thermal shock is a rapid and sudden change in temperature which can cause glass to crack or shatter.
The easiest way to prevent thermal shock is to heat or cool glass slowly. So, when freezing glass, don’t put it in the freezer if it’s still warm.
Allow the glass to cool to room temperature before putting it in the freezer. And, when taking it out of the freezer, allow the glass to warm slowly.
Also, make sure that you check the glass for cracks or damage to your glass before freezing it. This damage can cause the glass to shatter or break much easier from thermal shock.
Freezer Safe Glass Containers
Another factor to freezing glass is what type of glass it is. In general, if a glass container is oven safe, it’s also freezer safe as long as you account for thermal shock.
If you want to know more about the types of glass used to make kitchenware, we have an in-depth explanation in another article here.
Here are a few examples of glass containers and how they do in the freezer:
1. Mason Jars
Mason jars are freezer safe as long as you take some precautions. As always, remember thermal shock and act accordingly.
It’s also important to remember that liquid expands when it freezers. So, if you’re freezing liquid inside a mason jar, make sure you leave about an inch or two at the top of the jar to allow the liquid to expand.
On the other hand, you should also keep in mind that if you plan on freezing something for a long period of time, the gap in the jar can give space for freezer burn to form.
But, if you’re not worried about freezer burn, mason jars are a great way to freeze and store food.
2. Pyrex Containers
Pyrex containers are a great way to store food in your freezer. Once again, make sure you try to prevent thermal shock.
And, just like with mason jars, make sure you leave room at the top for liquid to expand.
But with pyrex containers, the lid is rubber and can allow a little expansion for the liquid. So, not leaving a big enough gap isn’t as big of an issue as it is with mason jars.
3. Drinking Glasses
Now, drinking glasses aren’t typically used for storing food but they can be good for storing leftover smoothies or milkshakes.
And, if you want to be really fancy, you can put a glass in the freezer to give yourself a nice chilled drink on a hot summer day.
But, since drinking glasses aren’t made for the freezer, I wouldn’t recommend leaving them in the freezer for long periods of time.
4 Tips for Freezing Glass Containers
Despite your best efforts, glass might break when you put it in the freezer. To try and avoid this, we’ve got a few tips to help prevent glass from breaking when you freeze it.
1. Cool and Warm Slowly
When you’re storing food in glass containers, no matter what kind of container you use, you need to cool and warm it slowly.
This will help prevent thermal shock and decrease the chance of the glass breaking.
you can do this two ways. If you’re storing leftovers, make sure the stuff you plan on storing is cooled before you place it in the container. Or, place it in the container first and then allow it to cool.
When taking a container out of the freezer, allow it to thaw at room temperature before trying to defrost it with any heat.
Doing this will greatly reduce the chance of glass breaking.
2. Avoid Using Shaped Containers
If you’re using mason jars, they are commonly made with ‘shoulders’ meaning they have a curve close to the top of the jar.
These shoulders make a stress point where pressure can build up and break the glass.
Any container that has a shape like this can create stress points. So, when freezing glass containers, it’s better to use jars or containers without shoulders or other potential stress points.
If you do use jars with shoulders, make sure you leave a large gap for the contents to expand. This will help reduce the pressure.
3. Leave Space at the Top
When you freeze food, particularly liquid, it will expand. So, when freezing food, make sure you leave a gap at the top of the container to allow for this expansion.
If you’re using mason jars, leave an inch or two below the lid line. Also, if you use lids, don’t tighten the lids all the way down when you first put it in the freezer or leave the lid off until it’s frozen.
Once it’s frozen, you can tighten the lid or place a lid on the container. This will help prevent pressure from building up in the container.
4. Leave Space Between Containers
Another thing that can cause glass containers to break is if they bump against one another. The clinking of glass can make the frozen containers break much more easily.
To prevent this from happening, keep some space between containers when they freeze. If you’re using Pyrex containers or something similar, the rubber lids create a kind of bumper for your glass.
Keeping space between your glass containers can reduce the chance of your glass breaking.
Can you put Pyrex glass in the freezer?
Pyrex glass is safe to put in the freezer as long as you take certain precautions. Warm and cool it slowly, avoid containers that are shaped in a way that could create pressure points, leave space at the top for expansion, and leave space between your containers.
Does glass break in the freezer?
There is always a chance that glass might break in the freezer. But, there are things you can do to prevent it from happening. Warm and cool the glass slowly, avoid shaped containers, leave space at the top for expansion, and leave space between your containers.
Can I use glass jars to freeze food?
You can use glass jars to freeze food, but you should take a few steps to prevent the glass from breaking or cracking. Specifically, you should try to avoid jars with shoulders and leave space at the top to allow for expansion. You should also leave space between jars to prevent them from clinking together.