Are Mason Jars Microwave Safe?

I love Mason jars. They are my travel mug, my storing piece, and my go-to jar for pickling. 

All the leftovers and half-eaten foods go right into my Mason jar which I store in my fridge. 

My family loves cold coffees that I chill inside Mason jars. I was recently wondering if I can use it inside the microwave. 

Let us find out!

Are Mason Jars Microwave Safe? 

The answer to this depends on certain circumstances. 

Ball 389579 Pint Regular Mouth Mason, 2 Count (Pack of 1), Clear

I hate these kinds of ‘it depends’ answers, but when it comes to microwaving mason jars, you do need to check a few things to make sure it’s safe.

Your Mason jars may or may not be suitable for microwaves.

It all boils down to a handful of considerations before placing your jar in the microwave. 

Allow me to elaborate!

Things to Consider Before Placing Mason Jars in the Microwave 

There are two things you need to consider before using it inside the microwave : 

How Old Is Your Mason Jar? 

The Mason jars that used to be made earlier are not microwave-safe. These are made up of thinner glass material. 

The newer ones are sturdy compared to the older batches.

Look for the ‘microwave safe’ tag beneath the cup, in the instructions leaflet, or on the box.

If you don’t find it, it is best to not place the mason jar inside your microwave. 

What Temperature Do You Wish to Use? 

Although newer Mason Jars are microwave safe, they are not tempered enough to withstand high heat exposure. 

Tempered glass is a specialized glass, that has fewer air bubbles. It gives protection from thermal shock. 

The Mason jars are mostly made with annealed glass. The ‘microwave safe’ category can bear thermal shock up to a certain temperature.

Use them at low to medium temperatures for a short duration of a maximum of 2-3 minutes. 

It is best to not heat the Mason jars beyond 400-450° F. 

You may be aware that microwaves work by heating the food particles and not the cookware.

However, heat transfer for a long duration and at a high temperature can cause the glass to become extremely hot. The Mason jar may crack, shatter and even explode. 

Once that happens it can damage your microwave for good. 

How Can I Find Out if a Particular Mason Jar is Microwave Safe? 

Look at the bottom of the jar. If you find a sign saying “microwave safe”, you can place it in the microwave. 

Another method of finding out is to empty all contents and place the jar in the microwave at low medium temperature for one or two minutes. 

Do this only for thick glass jars. Do not attempt this method to microwave a thin glass Mason jar that does not have a microwave-safe label. 

Can I Heat Mason Jar with Frozen Food in a Microwave? 

Not at all. I would strictly advise you from doing so.

Allow the frozen food to thaw till room temperature.

After that, you can microwave the ‘microwave safe’ Mason Jar for two minutes. 

The reason is the glass surface. As soon as the temperature increases, the glass will expand due to stress and fracture.   

For thawing, the best practice would be to melt the frozen food in the jar in water. Take a large bowl of water and submerge your Mason jar.

Keep changing water until the jar has thawed. 

You could also keep it at room temperature and once the contents have thawed, heat it in the microwave. 

Alternatively, you could remove the thawed contents in a pan and then microwave the food. 

If you must microwave and are running short of time, place the Mason jar in a bowl of cold water. Open the lid and microwave slowly in intervals. Each time microwave for 20 seconds at a stretch.

Replace water and repeat the 20 seconds interval until the contents are done. 

Can I Microwave the Lid of the Mason Jar? 

The lid of the Mason jar is made of metal. This metal corrodes with time.

Once it corrodes, you cannot eat any product inside the jar. 

As the metal is corrosive, do not place it inside the microwave.

Always remove the lid before microwaving your Mason jar

For How Long Should I Microwave Mason Jars? 

If you wish to sanitize your Mason jars, microwave them for one to two minutes. 

Clean the jars with warm soapy water or baking soda and vinegar.  Wipe them dry.

Microwave a one-liter jar for one to two minutes. 

Some Common FAQs about Mason Jars

Below are some common questions people have aout using mason jars

Can Mason Jars be Recycled? 

Most of the Mason jars are made from recyclable annealed glass. However, the rubber rings cannot be recycled. 

Instead of recycling them, you can paint them and use them to store accessories, decorate rooms, etc. 

Can I Bake Food in a Mason Jar? 

I wouldn’t recommend baking food in a mason jar. This is because the glass will not be able to withstand the heat required for baking! 

Mason jars are not tempered enough to be heat resistant at high temperatures. Make sure the Mason jar is oven safe before baking food in it. 

If it is, baking food is still not a good idea as the heat will not reach the central area in the jar. The part left uncooked will have germs. 

Skip the baking and instead use the jars for storing food and drinks at room temperature. You can also store use it for cold storage inside the fridge. 

Can I Freeze Mason Jars? 

Yes, you can use Mason jars to store leftover food, juices, and coffee in the fridge. 

Glass does not react with food. Mason jars are far better for storing food compared to plastic jars. 

With the right recipes, you can store pickles, canned food, and other food for many months. 

However, you need to know the right method of using the jar to extract maximum benefit. 

Here is how 

  • Look for the freeze-fill line on the jar. You will find it below the rings. Approximately an inch down. Most branded Mason jars have it. The designated line indicates that you can safely fill your food up to the line for freezing. Overfilling beyond the freeze fill line will crack your glass jar.
  • As everything gets frozen together, place it in a cardboard box before freezing to avoid undue stress on the glass surface. 
  • The food or liquid you wish to store in your Mason jar should be at room temperature. Hot food can cause the glass to crack due to sudden temperature shock. 
  • Always thaw the jar and its contents at room temperature before using.

Can I Wash the Mason Jar in a Dishwasher? 

Yes, most of the Mason jars are dishwasher safe. It is a good idea to refer to the instruction booklet or reach out to customer care to be sure. 

The lid may or may not be dishwasher safe depending on the quality of metal. 

You can also wash the jar by hand with the help of warm soapy water or salt and vinegar.

I would recommend hand washing to increase the lifespan of Mason jars and keep them looking new. 

How to Best Use Mason Jars? 

Mason jars are the best alternatives to coffee, tea, juice, and soup mugs. If you don’t feel like finishing it up, you can put the lid and store it away. 

Take Mason jars along with you while traveling outdoors. It is far better compared to paper and plastic mugs. 

Use them for canning or pickling. Just make sure the liquid or oil that you use is not hot. Fill room temperature foods and enjoy them for months!  

You can freeze Mason jars in the fridge or refrigerator and store food for months. As the glass jar expands on exposure to low temperatures, it might crack or break. 

It is best to store them in a cardboard box and then inside a freezer. You may also use old fabric to cover them up. 

Conclusion 

Summing up, only microwave-safe Mason Jars should be placed in the microwave. Look for the label at the bottom of the jar. 

Make sure to place a thick glass inside a microwave. Do not use it for a prolonged duration at high temperatures. A maximum of two to three minutes is sufficient for reheating the contents inside.

Do not place the lid inside the microwave. If the glass is thin, do not microwave it or it might shatter into pieces inside the microwave.

When storing, make sure the food or liquid is at room temperature. Similarly, after taking out the frozen mason jars, allow them to thaw at room temperature. 

Mason Jars are signature glass jars with a lid that have multipurpose uses. You can use it as a traveling mug, an accessories box, a decor item, coffee, tea, soup, and juice mug.

You can also use it for storing canned and pickled food for many months. Enjoy your jars!

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