From preserving foods to creating home decor, Mason jars have many uses. But no matter what you use them for, you'll want to know the ins and outs of using them properly. That’s why we’ve compiled the following list of the most frequently asked questions about Mason jars to ensure your safety and satisfy your curiosity.

Further Reading: Is it safe to freeze a Mason jar?

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Are Mason jars dishwasher safe?

Yes! Mason jars can be washed by hand or in the dishwasher. However, the metal Mason jar lids may become worn down by detergents. We encourage you to wash and sterilize your Mason jars by hand for the best results. Also, make sure you treat the jar’s lid and seals with the same care. If you are placing your jars and lids on a towel to dry, make sure the towel is fresh and clean.

Mason jar cleaning supplies

Are Mason jars microwave safe?

The consensus is that Mason jars are microwave safe; however, you must be watchful. Glass reacts to heat, so a Mason jar should not be in a microwave for more than five minutes or it will be at risk of shattering. Try to locate the “microwave-safe” statement on your jar before you begin, but if you cannot find the certification, it’s best to keep your jar out of the microwave.

When microwaving the jar, be sure to remove the metal lid beforehand. Also, older Mason jars may break under high temperatures. Do not microwave frozen Mason jars.

Can I pour boiling water into a Mason jar?

Yes, you can pour boiling water into your Mason jars, and you can also insert them into a pan full of boiling water for sterilization. However, make sure your Mason jars are at least room temperature before placing them into the water. It is even better to let your jar heat along with the water’s temperature instead of putting it in the water after it has reached its boiling point. If the jar is too cold, lowering the jar into the boiling water may cause the jar to break.

Assortment of Mason jars

Can I put my Mason jar in an oven?

No. Keep your Mason jars out of the oven. Kacey Christian from the National Center for Home Food Preservation says that oven processing times are inaccurate, the temperature fluctuates too much, the oven’s dry heat is unsafe, and the jars are much more likely to shatter.

How long will food last in a Mason jar?

If sealed and stored correctly in a cool and dark place, the National Center for Home Food Preservation says that canned food will retain its quality for 12 to 18 months in a Mason jar. It is important to remember that the condition of the food will degrade as more time passes. Regularly reorganize your Mason jars by date and check the seals to determine the condition of your canned goods.

What are some Mason jar sizes?

Mason jars come in a variety of sizes and sets:

Do you have a bunch of Mason jars already? Let’s find the size of those Mason jars.

Are Mason jars recyclable?

Yes! For safety reasons, however, you should separate the glass from other recyclables due to Mason jars’ tendency to shatter. We recommend that you instead try to sterilize your Mason jar and reuse it. Packaging food is not its only purpose as these jars can also be used for arts and crafts, and a whole array of DIY projects.

Blackberry Freezer Jam Mason jar

Do I need to leave space in a Mason jar?

There should always be room above the product in your Mason jar, especially when it comes to perishables—this is referred to as “headspace.” The general rule is that there should be at least an inch of space between your food and the lid because this creates a tight seal. However, the amount of space you need depends on what foodstuff is in your Mason jar, so make sure to do your research beforehand!

What causes Mason jars to break?

There are several reasons why a Mason jar might break, including, but not limited to:

  • Hairline cracks
  • Lids that are too tight
  • Placing hot food in cold jars
  • Placing cold jars in hot water
  • Old age
  • Overfilling
  • High pressure

What do I do if my Mason jar lid gets stuck?

If you find yourself unable to remove your Mason jar lid and seal, first try running it under hot water for at least 30 seconds. It does not need to be boiling, as the goal is just to get the lid to expand. You do not need to get the glass jar wet either. If that does not work, try using rubberized gloves that will allow you to get a better grip on the jar’s lid. We do not recommend attempting to pry the jar open with a knife or any other tool for safety reasons.

Mason jars team

Want to Learn More?

We’re here to answer all of your questions about Mason jars. If our list of frequently asked questions does not cover all of your canning inquiries, join our newsletter for more updates or contact us today! You may also find additional help on our Customer FAQs and Get Inspired page.