Can You Microwave a Mason Jar?

You may have used a mason jar to make your own fruits and vegetables. My family uses them quite a bit down here in the South.

They are excellent to use when preserving foods from your summer garden. Then you can reheat and eat the food in the winter.

So, the question has probably occurred, can you microwave a mason jar? Yes and no, depending on the brand. You should not microwave older mason jars. They might shatter when exposed to the heat in a microwave. 

In this blog post, we will answer all of your questions about microwaving mason jars. 

What is a Mason Jar?

Mason jars are glass jars used to can and store food. Mason jars are usually made of thick, clear glass and have a wire bail lid and a screw-on ring. 

The rings can be reused many times, but the lids should be replaced each time. Mason jars were first used and patented in the mid-1800s by a man named John Mason.

He ended up losing the patent, but the word “mason” became a generic trademark name for these jars! 

Today, mason jars are still popular for home canning because they are durable and easy to use.

Related: Can you microwave cold glass?

What are Mason Jars Made Of?

The original mason jars were made with transparent aqua glass. Today, many manufacturers are using tempered glass to make mason jars.

Popular Mason jar Brands:

  • Ball

One of the most popular Mason jar brands in America, Ball makes jars that come in a variety of sizes and shapes. The company also offers a wide range of lids, including ones with straws and handles.

The Ball Mason jar is to be used only for home canning recipes, cold or room temperature food storage, cold beverages, and crafting. 

You CANNOT microwave a Ball mason jar. It is not made with tempered glass. Only microwave if there is a microwave-safe label on it.

  • Kerr

Another well-known American Mason jar brand, Kerr produces jars in both traditional and wide mouth sizes. The company is known for its extensive line of Mason jar accessories, including storage caps and drinking lids.

Do NOT microwave Kerr mason jars unless you see a microwave-safe symbol on them.

  • Weck

A German Mason jar brand, Weck produces jars made from thick glass that can be used for both home canning and fermenting. 

Jars from this brand often come with rubber gaskets and clamps to create an airtight seal.

  • Le Parfait

A French Mason jar brand, Le Parfait offers a wide range of glass mason jars in both square and round shapes. 

This brand is best known for its wire bails that help keep the lid secure during transport or while shaking the jar.

How to Test a Mason jar for Microwave Use

If there is any doubt on whether a mason jar is microwave-safe or not, you can do a test to find out! Just follow the steps below.

  • Step 1: Fill the Mason jar in question with a cup of water.
  • Step 2: Place the Mason jar in the microwave.
  • Step 3: Set the microwave to the highest setting and microwave the Mason jar for approximately one minute.
  • Step 4: After one minute, check the jar. If the Mason jar is hot to touch, it is not microwave-safe. If the Mason jar is cool to touch, you can safely use it in the microwave.

Microwaving a Mason Jar to Sterilize It

One reason you may be wondering, can you microwave a mason jar, is because you want to sterilize it quickly for your canning needs.

  • Step 1: Make sure your mason jar is microwave safe. If it doesn’t specifically say it can be used in the microwave, then it’s not microwave-safe.
  • Step 2: Clean the jar. Use detergent and a tablespoon of baking soda to thoroughly clean the Mason jar.
  • Step 3: Check jars for cracks. Microwaving jars with cracks can cause shattering.
  • Step 4: Prepare an area on the counter with a towel to place the hot jars when removed from the microwave.
  • Step 5: Wet the Mason jar inside and out. This helps the jar heat up quicker and more evenly.
  • Step 6: Put 2 tablespoons of water in the jar. This will help the steam rise and sanitize the jar.
  • Step 7: Microwave for 2 minutes on the highest setting. Anymore and the glass could shatter. The goal is to get the jar hot and for the water to turn to steam.
  • Step 8: Take jars out of the microwave and place on the towel on the counter to dry. Be careful, as jars will be hot. You are ready for canning!

Microwaving a Mason Jar to Reheat Food

Many people use mason jars to store different foods for long periods of time! If you need to heat up food in mason jars using the microwave, follow these instructions.

  • Step 1: Make sure your mason jar is microwave safe. If it doesn’t specifically say it can be used in the microwave, then it’s not microwave-safe.
  • Step 2: Check jars for cracks. Microwaving jars with cracks can cause shattering. Double check and make sure your jar doesn’t have any cracks in it from being stored.
  • Step 3: Take the lid off the jar. Never microwave a metal lid with the Mason jar. If you need too, cover the Mason jar with a paper towel.
  • Step 7: Microwave for 2 minutes on the lowest setting. Start at the lowest setting at 2 minutes. Check the jar and make sure it’s not too hot. Continue microwaving on 30 second intervals until food reaches desired temperature.
  • Step 8: Take mason jars out of the microwave once food has been heated. Enjoy!

Can you Microwave a Frozen Mason Jar?

Unless the jar and brand specifically say its freezer safe, do NOT freeze a mason jar. And regardless of whether a mason jar is freezer safe or not, do NOT microwave a frozen mason jar. 

If the Mason jar is exposed to extreme temperature changes, it can experience thermal shock and cause the glass to explode.

How to Defrost a Frozen Mason jar

Instead of defrosting a frozen mason jar in the microwave, try this method. Grab a large bowl and fill with room temperature water. Place the Mason jar in it. 

Every thirty minutes, change the water. Once the jar and food has thawed out, you can use the microwave to heat up the food.

But, of course, if you’re running low on time, or need something quick, as long as the jar say it’s microwave-safe, then go ahead and use it!


Can You Put a Mason jar in the Freezer?

Mason jars can be placed in the freezer if they have a freezer safe label, but it is not recommended for longer than 6 months. 

The jars may break or the lids may blow off from the expansion of the contents. If you choose to freeze mason jars, do so with caution. 

Fill the jars no more than three-quarters full, leave room for expansion, and place them in the freezer on a flat surface. 

Monitor the jars closely and do not store them for more than two months. When you’re ready to use a frozen mason jar, thaw it in the refrigerator overnight before opening.

Can You Put Mason Jar Lids in the Microwave?

NO! Never put mason jar lids or the rings in the microwave. They are made with metal. 

Microwaves cannot penetrate metal and the waves will bounce off and cause sparks. You risk starting a fire if something combustible is also in there.

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