What to Do If Your Canning Jars Don't Seal

Canned beans on table
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When canning your own food, you will occasionally get a jar or a batch of jars that fail to seal after processing. While frustrating, it's a problem that can be resolved easily by reprocessing the jars.

What You Need to Recan Jars

The only item that you may need to purchase when recanning is a new set of lids. The lids are one-time use and will not seal a second time. The good news is that they are inexpensive and you can pick up a dozen for less than $5 almost anywhere that sells canning supplies.

  • A new canning lid.
  • The original jar and canning ring filled with preserves
  • A water bath or pressure canner

How to Reprocess Unsealed Canning Jars

Follow these steps and read through the tips before trying to recan your preserves. It may have been a fluke that your jars did not seal the first time, but you may have accidentally skipped an important step. It never hurts to refresh your memory, and it may save you time in the end.

  1. Check each jar for nicks along the rim.
  2. If you find a nick, transfer the contents to a new jar. If you don't find any nicks, put a fresh lid on the jar and secure it with a ring.
  3. Reprocess the jars using the same processing time as before.
  4. Allow the jars to cool.
  5. Check for a good seal.

Tips for Recanning Your Preserves

  • Canning lids can only be used one time, so always start with a new lid.
  • Unsealed jars may be stored in the refrigerator for immediate use.

Why Didn't My Jars Seal?

To avoid having unsealed jars again, it is important to know why they might not have sealed in the first place.

These factors can play a role in a successful canning experience.

  • The jar was not filled properly. Successful canning requires that there is a certain amount of 'headspace' between the food and the top of the jar. Your canning recipe should specify this distance (typically 1/4" to 1"). If you cannot fill up the last jar, save it in the fridge and use it first.
  • The top of the jar was not clean. After you remove air from a full jar of preserves, make sure to clean the edge with a damp cloth, or it may not seal.
  • The lid was not centered. The canning jar lid has a sealing compound on the bottom that is designed to be in contact with the jar's rim. If this is too far out of alignment, the seal might not hold. (This compound is also why lids cannot be reused when recanning.)
  • The ring was too tight. When tightening the ring onto the jar, it needs to be secure but not too tight. Air needs to escape during the process, and a super tight ring may not allow this.
  • Did you hear the ping? After removing jars from the canner, you should hear a 'ping' as each jar cools. This sound means that the jar has sealed properly.