Are Mason Jars Microwave Safe? Here's What To Look For

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Mason jars are a wonderful item to keep in the kitchen. Not only are they great for storing delicious homemade jams and spreads, but they also create airtight seals for dry goods like pasta, rice, and flour. You can make your favorite matcha drink in them too, or use them to serve up a range of foods like salads and oats. However, you do need to be careful if your food needs to be warmed because while many mason jars are microwavable, some of them are not.

In fact, one of the most recognized canning companies in the U.S., Ball, does not make microwave-safe mason jars. Ball jars can be slightly heated, but only in a hot water bath at a temperature of 180 degrees Fahrenheit. This is because they're made from annealed glass, which hasn't been tempered to withstand heat. The danger of microwaving annealed jars from any brand is that they can break, and the last thing you want is to be cleaning shards of glass out of your microwave. To check if your jar is made with tempered glass, look for a microwave-safe label on the bottom. If you can't find one, it's not worth risking it.

A lot of brands make microwave-safe mason jars, like Le Parfait and Kerr Mason Jars. However, there are a few things to consider. Metal cannot go into the microwave, so make sure to remove any lids or metal rings first. If your jar has a metal mount, it's not microwave-friendly. Additionally, microwave-safe jars should only be heated in short bursts. Even tempered glass runs the risk of shattering if heated for more than five minutes. It's best to pack your jars with items like meal prep pasta dishes and light soups, rather than meals that need to be reheated for a longer period. Don't forget to be careful when you remove any jar from the microwave. The glass can become very hot to touch, so wait a few minutes or use a cloth or oven glove to  protect your hand. 

It is possible to put hot liquids and foods into Ball jars, as long as you heat them in a water bath first. Again, keep in mind that the glass will heat up. Finally, always check your jars for any cracks before heating, and avoid putting anything that can nick them inside, like metal cutlery or glass straws.