How to Check That Your Seal is Good

concave lids
I got a question tonight from a reader of this blog about seal quality and as I was writing her back, I realized that there may be more of you out there who could benefit from a brief seal-testing tutorial.

When it comes to canning, sometimes you miss the pinging sound that gives you auditory confirmation that your jars have sealed. Just because you didn’t hear it doesn’t mean that the jars didn’t seal. Here are some ways to test….

  1. Press down on the center of the lid. Does it move up and down or does it feel solid and concave? Solid and concave means a good seal, movement means no seal.
  2. Tap on the lid. Does it sound tinny or hollow? Tinny means sealed, hollow means poor or no seal.
  3. Unscrew the band you used to hold the lid in place during processing. Now attempt to pick your jar up holding onto nothing but the lid. If you have a good seal, you should be able to do this easily. You’ll know pretty much right away when you remove the band whether your seal is good.

How else do you guys check your seals? And, while I’m answering questions, who else has got one?

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223 Responses to How to Check That Your Seal is Good

  1. 101
    Britney Adams says:

    Hi ladies,

    I made strawberry jam last weekend and all the tops sealed. However, today I noticed one was up and when I touched it, it went down and has stayed down. Should I throw this one out?

  2. 102
    Callandra says:

    Great Article! We just made our first batch of pickles – the jars were just a touch too big for our canning pot, so when we took the lid off of of the first batch, we realized the water was about 1/2 below the top of the lid. I popped those back in for about the time I think the water was too low. One of the lids is now convex – I am assuming that seal didn’t work? Two questions
    1) How long do i wait to actually eat pickles ( they need to sit right?)
    2) How long will the one with the crappy seal last in the fridge?

    Thanks so much!

  3. 103
    Lori says:

    Canned pickled cabbage. All jars appeared to seal. Heard them ping and all are depressed or concave. Theres no give in the lid. However, at the right angle I can see a slight ring in the center. Are these sealed and safe?

  4. 104
    Stephanie says:

    I pressed the middle of the lids down before some of the jars had a chance to pop on their own. I’m a first timer and didn’t realize that I wasn’t supposed to touch them! They’re staying down on their own now (not going up and down when I press on them). Did I screw up my pickles??!! Lol Or will they be ok? Thank you 🙂

  5. 105
    Cynthia says:

    If they didn’t seal what do you do?

    • 105.1
      Marisa says:

      If you caught the seal failure within the first 48 hours, you can either put in the fridge or try to reprocess is (though if the texture of your preserve is important, this isn’t the best option). If a jar isn’t sealed and it’s been awhile since you made it, it’s better to throw it away.

  6. 106
    Megan Aasen says:

    Hello, i have made several jars of pickled beans and they all sealed until yesterday now i cannot get a seal? i haven’t changed anything and the pickled carrots seal it is just the beans that refuse to seal now.

    • 106.1
      Marisa says:

      Could it be that you’re using a different batch of lids? Are you doing the boiling water bath process properly? There’s no reason that I can think of why your beans wouldn’t seal while everything else does.

  7. 107
    Lana Johnson says:

    I made cran-blueberry jam recently and all four lids popped, so I felt sure they were all sealed. Days later, not sure how many, but under a week we discovered one lid unsealed. We immediately put it in the fridge, but are unsure now if it’s safe to eat. What do you think?

    • 107.1
      Marisa says:

      I think it’s fine. The worst that can happen with that jam is a little mold. If the surface looks entirely normal, it is safe to eat.

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