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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118 Responses to How to Check That Your Seal is Good

  1. 51
    Tiffany says:

    Can I seal the jars by the heat of the content alone because I’ve done that and they sealed, made a popping noise and everything and they’re completely sealed without the water bath, is that ok? I sanitized my jars and lids first.

  2. 52

    […] while they were boiling. Not all of my cans sealed properly (I found some simple tests for seals here), so I reprocessed them the next day for another 15 […]

  3. 53
    Stacy Dominguez says:

    If the edges of the lid is sealing (sticking ) to the jar, but the center you can still push in a little what should I do……
    I have about 5 out of 9 that are doing this and I have done taken off the lid recleaned it and wiped the top of the jars clean again and placed them in boiling bath twice.

    • 53.1
      Marisa says:

      Stacy, how long are you letting the jars achieve full seal? You need to let them seal for at least 24 hours before you take any action. And are the lids actually moving up and down? Or is it that there’s just a tiny bit of give? As long as they’re concave and don’t actively pop up and down, they are sealed. A tiny bit of give is okay.

  4. 54
    Liz says:

    I just made a batch of rhubarb jam (first time canning by myself) – and after I let them cool for 24 hours, I tried picking each one up by the lid only. One jar had a tiny bit of give in one spot, but it still stayed sealed. Is the seal still good enough to be safe?

    • 54.1
      Marisa says:

      The lid can have a tiny bit of give, as long as it isn’t clicking up and down. If the seal held when you lifted it holding the edges, it should be fine.

      • Liz says:

        Sorry, just to make sure – the seal held when I lifted it holding the edges, but I did feel an edge of it loosen (or the jar moved downward a bit while holding it up by the lid) – is that what you said was still okay!

        Thanks so much!

        And thanks for everything on the site – it’s been so helpful! (I know a roommate of mine who let me help her can, and she used foodinjars extensively.)

        • Marisa says:

          Liz, if it felt like the lid was loosening, then the seal is not good. Did you give the jars 24 hours to seal before you started checking the seals? They need to be fully cool before you start testing.

          • Liz says:

            I did give them 24 hours, so I’ll reprocess it in a new jar and hope for a tight seal this time!

            Thanks for all your help!

  5. 55
    Joyce says:

    This evening I canned 12 pints of dill green beans. i did not hear any of them ping. The lids do appear to be pulled down (concave). Tomorrow (24 hour) I go through your 3 tests. If some did not seal you said I can reprocess. Can you go through the steps I would need to do to reprocess. Thanks. I’m a little bummed, I love hearing the ping.

  6. 56
    Mal says:

    Hi!! Tonight was my first time canning, and I didn’t know about the do not test the seal rule until 24 hours. I tested mine while still hot… Did I ruin them? What can I do? I’m really worried I messed everything I did up, thanks!!!

    • 56.1
      Marisa says:

      Did the lids come off when you were testing the seals? If so, they are ruined and will need to be processed again. But if the lids stayed in place, all is well.

  7. 57
    Jesse says:

    one of my jars had not popped yet but I touched the top of it and it popped in is it ruined that I did it myself and it didnt do it on its own ?

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