Can You Freeze Mason Jars & How to go about it.

Mason Jars are extremely useful to have at home, and we’ll go over why.  Nevertheless, yes, you can freeze mason jars! It is also good to point out that if for some strange reason the jar shatters in your freezer(because of the temperature), you won’t have much(if any) mess.

However, we will make sure to show you how to avoid this(relatively easy), and contribute to your Zero Waste lifestyle. 

And, if you were wondering, a mason jar is made out of molded glass, and one of the most popular ways to preserve food at home. 

Mason jars are great for decoration, and an excellent replacement for plastic containers. 

Moreover, they are easy to get(i.e., you can use the ones you buy tomato sauce or any of your juices). 

Why Do Mason Jars Break In The Freezer?

Fruits in mason jars

The main reason a frozen jar can break is because of thermal shock. Namely, when your jar goes through a swift shift in temperature. 

Thermal shock, by definition, is a “mechanical load caused by a rapid change of temperature.”

This is typical when, for example, you take a recently finished dish from room temperature (but boiling) and stick it into a mason jar and into the freezer. 

Additionally, if you do not give enough space to the content of your mason jars they are likely to shatter, but more on that in a second. 

How To Put Mason Jars In The Freezer

To freeze mason jars, you:

1) Make sure you let the content of what you plan on putting in your mason jar cool. 

2) Having the right type of mason jar is a must. 

You want to make sure that you have straight side jars (also known as quart jars). Mainly, you want to make sure that the jar does not shift shape from top to bottom. 

In case you do not know the difference between straight side jars or ones with shoulders (where there is a shift), we got you covered below. 

That being said, you can still try with mason jars with shoulders. 

Shoulder jar with berries
Shoulder Jar
Squared jar with blueberries
Straight Jar

3) Choose the right type of glass. 

 The type of glass you use is essential. Freezing in mason jars that are not the right type of glass makes it that more likely to suffer from temperature changes and broken glass. 

What you want in this regard is tempered glass.  Essentially, tempered glass is a tougher version of regular glass; it is specifically manufactured to be more robust than regular glass. 

A glass that is not tempered usually suffers from air bubbles(at a very miniature level) when it goes through temperature changes. 

These changes can lead to broken glass due to an explosion. 

To freeze mason jars; let the content cool down, choose straight jars with tempered glass, and leave sufficient space on top.

4) Leave sufficient space at the top (headspace). 

Make sure you leave ample space at the top of your container regardless of the type of jar that you freeze.  

For both types of jars, you will want between 1 to 2.5 inches(this is also known as headspace).  The difference lies as of when you will apply this space.  

Namely, for the shouldered jar, space should be below the shoulders. For the straight jar, do your measurements from the top. 

The reason you need to leave space at the top is that when food freezes, it expands. Glass jars that break other than through temperature change is because of expansion.  

You can find plenty of measurements online about the headspace you should leave for jars. The point is, leave space at the top; the bigger your jar, the more space you should allow! 

If you still have some doubts about the space you might need, you can also try to freeze the mason jars without a lid.  

Another solution for your mason jar is to place your jars in your freezer sideways.  In this way, all your jars will benefit from more space. 

If that is not enough, then you can also make sure the lid is not too tight. 

By keeping the cover of your mason jars a bit loose, you make sure that there is a bit of air that can get out as the food or liquids inside, expand. 

While this may sound obvious, make sure you keep the mason jars away from the cooling side of the freezer. 

Jars with corks in them

What Can You Freeze In Mason Jars?

You can freeze any fluids or solids. Typically, for glass freezer containers, you’ll see anything from soups to fruits like berries and bananas. 

In terms of liquids, however, our earlier tip about leaving some space in the container is even more critical. 

The logic is simple; if you fill a jar with fruits and freeze it, there will inevitably be small pockets of space, allowing the fruit to expand when they freeze. 

However, if you apply the same logic to liquids, keep in mind that you will not have these pockets of air space. So be extra careful with liquids.

Other Tips

  • If you plan on leaving more than one mason jar in your freezer, then it would be a good idea to label them.  We recommend you use washi masking tape and a permanent marker, making the perfect glass freezer container. 

  • Be careful with storing the lids of your jars. It is quite common to see that the lids of your jars rust. This happens because of where you store them, namely in a humid place,  near the sink.  What you want to make sure is to keep these lids in dry areas; above all, avoid plastic lids.  

  • When thawing your frozen food or liquids, make sure to distinguish one from the other. You can simply shake fruits for example, but liquids we suggest to let them de-freeze slowly outside of your freezer.   In either way, it would be best to take the frozen jar from the freezer and let it unfreeze gradually. First, in your refrigerator for a few hours, and then at room temperature if still necessary. 

Final Thoughts

Mason jars are the way to go when it comes to glass containers to have at home. 

Whether you have a mason jar with shoulders or straight side jars, you can do a lot of your food storage with these glass jars.  

There’s a reason they are one of the most famous Zero Waste Swaps promoted.

These jars are suitable for both liquids and solids. Moreover, mason jars are great for decoration in any way. 

As long as you know how your freezer works and how to freeze your jars, then you’ll be fine. 

Also, do not forget to avoid plastic lids(or any plastic for that matter) as much as possible.  Feel free to reach out to us with any comments or questions.

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