---
title: "Can you microwave mason jars? No"
description: "No — canning jars are soda-lime glass, not heatproof, and the metal lid arcs. What actually happens, what goes wrong, and what to do instead."
url: https://atoneplace.net/can-you/microwave-mason-jars/
site: "At One Place"
---

# Can you microwave mason jars?

**No: No — canning jars are soda-lime glass, not heatproof, and the metal lid arcs.**

Mason and Kilner jars are made to survive a slow water bath, not the steep local temperature gradients a microwave produces. They are soda-lime glass rather than borosilicate, so a hot spot next to a cool region can crack them, and the risk is highest when the jar comes out of the fridge. The two-piece metal lid is a second problem, since it will spark. A few brands now sell jars specifically marked microwave-safe; those are the exception and they say so on the glass.

## What goes wrong

- Thermal shock cracks the jar, sometimes while you are holding it
- The metal lid and band arc against the cavity
- A sealed jar builds steam pressure with no way to vent

## What to do instead

- Decant into a bowl or a mug
- Stand the sealed jar in a bowl of hot tap water for a few minutes to take the chill off

## Other "can you microwave" questions

- [Can you microwave styrofoam?](https://atoneplace.net/can-you/microwave-styrofoam/) — It depends — Only if the container is labeled microwave-safe, and most takeout foam is not.
- [Can you microwave aluminum foil?](https://atoneplace.net/can-you/microwave-aluminum-foil/) — No — No — foil reflects microwaves and the edges arc, which can start a fire.
- [Can you microwave plastic containers?](https://atoneplace.net/can-you/microwave-plastic-containers/) — It depends — Only ones labeled microwave-safe — cold-storage tubs are not among them.
- [Can you microwave eggs?](https://atoneplace.net/can-you/microwave-eggs/) — It depends — Beaten or pricked eggs, yes. A whole egg in its shell will explode.
- [Can you microwave Tupperware?](https://atoneplace.net/can-you/microwave-tupperware/) — It depends — Yes, if that specific piece carries the microwave-safe symbol on its base.
- [Can you microwave paper plates?](https://atoneplace.net/can-you/microwave-paper-plates/) — It depends — Plain white paper plates are fine; anything with metallic trim or a foam layer is not.
- [Can you microwave metal?](https://atoneplace.net/can-you/microwave-metal/) — No — No — metal reflects microwaves, arcs at edges, and can damage the oven or start a fire.
- [Can you microwave breast milk?](https://atoneplace.net/can-you/microwave-breast-milk/) — No — No — microwaves create hot spots that scald a baby even when the bottle feels cool.
- [Can you microwave takeout containers?](https://atoneplace.net/can-you/microwave-takeout-containers/) — It depends — Only if the container is marked microwave-safe — most are not, and metal-handled ones never are.
- [Can you microwave cardboard?](https://atoneplace.net/can-you/microwave-cardboard/) — It depends — Plain dry cardboard is usually fine briefly; anything with glue, staples, wax or foil is not.
- [Can you microwave glass?](https://atoneplace.net/can-you/microwave-glass/) — It depends — Yes for ordinary heatproof glass; no for leaded crystal, and never straight from the freezer.
- [Can you microwave water?](https://atoneplace.net/can-you/microwave-water/) — It depends — Yes, but very clean water can superheat and erupt when you move the cup.

## Common questions

### Can you microwave mason jars?

No — canning jars are soda-lime glass, not heatproof, and the metal lid arcs.

### What happens if you microwave mason jars?

Thermal shock cracks the jar, sometimes while you are holding it The metal lid and band arc against the cavity A sealed jar builds steam pressure with no way to vent

## Related pages

- [Can you microwave styrofoam?](https://atoneplace.net/can-you/microwave-styrofoam/)
- [Can you microwave aluminum foil?](https://atoneplace.net/can-you/microwave-aluminum-foil/)
- [Can you microwave plastic containers?](https://atoneplace.net/can-you/microwave-plastic-containers/)
- [Can you microwave eggs?](https://atoneplace.net/can-you/microwave-eggs/)
- [Can you microwave Tupperware?](https://atoneplace.net/can-you/microwave-tupperware/)
- [Can you microwave paper plates?](https://atoneplace.net/can-you/microwave-paper-plates/)
- [Can you wash pillows?](https://atoneplace.net/can-you/wash-pillows/)
- [Can you wash sneakers in the washing machine?](https://atoneplace.net/can-you/wash-sneakers/)
- [Can you recycle pizza boxes?](https://atoneplace.net/can-you/recycle-pizza-boxes/)
- [Can you reheat rice?](https://atoneplace.net/can-you/reheat-rice/)
- [Can you recycle plastic bags?](https://atoneplace.net/can-you/recycle-plastic-bags/)
- [Can you recycle batteries?](https://atoneplace.net/can-you/recycle-batteries/)

## Sources

- US Food and Drug Administration — FDA (https://www.fda.gov/) [Public domain (US Government)]