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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131 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 ?

    • 57.1
      Marisa says:

      As long as the lid remains concave, the seal should still be good. Sometimes, you just happen to touch it just as it was going to seal.

      • Jesse says:

        Thank you :)

        • Lindsay says:

          I’m glad you asked this because I just did the same thing! I thought they looked concave all except the little button so I touched the tops and they all went down! They had been finished about an hour, so I think I got too anxious. I’ll be testing my seals tomorrow!

  8. 58
    Kelly says:

    I was canning hot sauce and did a boil bath for 30 minutes. I let the jars completely cool down for several hours then I did the finger test. As I did the finger test some jars were not sealed but the lid did not pop back up creating a seal. All the jars seem sealed now as I did the finger test again the morning after. Could they be sealed properly now?

    • 58.1
      Marisa says:

      Yes. Sometimes jars take up to 12 hours to fully seal. Don’t test seals until the jars are cool.

  9. 59
    Erin says:

    How long does it take pickles to seal properly. I made them last night. Finished canning around 11pm. This morning at 8am i tested some of them did not realize about the 24 hour rule. Some of them popped down as i touched them. Does this mean that the seal failed. Do I need to reseal them. I will will test them when i get home. I Believe you mentioned if you catch them within 24 hours still okay to reseal them. I am correct in understanding this.
    Thank you.

    • 59.1
      Marisa says:

      Any jar should seal as it cools. My guess is that your pickles did not seal. Unfortunately, resealing pickles is a tricky prospect, because when you can them a second time, you seriously impact their texture. If it’s not a huge batch, I’d suggest popping the unsealed jars into the fridge.

  10. 60
    Julia says:

    Ladies you might want to go to Jardin and read about their new seal procedures. They are no longer recommending that you boil seals. This applies to water bath, which they state when overheating the seal in boiling water the plastisol spreads out too thin. So they recommend that you just simmer lids and you should always cook foods 10 minutes or longer to take care of sterilization. They also state that when you are you pressure canning that you can get a good seal because the plastisol when heating against the glass rim gives a good seal. Their new boxes reflect this change but as we know you should buy from a store that does not pull out old stock that they don’t sell during canning seasons.

  11. 61
    Liz says:

    After sealing my jam, I noticed that when I taken the ring off, there was some jam around the edge. The jar is sealed, did I do something wrong or is it ok?

    • 61.1
      Marisa says:

      That kind of minor leakage during sealing is normal. Just wash the jars in some warm, soapy water before putting the maway.

  12. 62
    Pam says:

    One of my jars sealed before I could get it over to the water bath (it pinged and is concave). If I process it will I ruin the seal?

    • 62.1
      Marisa says:

      It won’t ruin the seal, because that initial seal you got was a weak one. You should still process the jar.

  13. 63
    Becky says:

    I water bath canned some pints of dill pickle chips. Let them cool and noticed the popping of lids a couple hours after I took them out.

    I didn’t realize the 24 hour rule until just now though. I did happen to wait until they were cool to the touch though. When I had touched one of the tops, it went down and stayed down. I’m hoping that one ends up being ok. Will wait until the 24 hour mark before trying to lift it though to make sure.

    My main question: one of the jars that popped on its own is a bit hinky. The center is down and there’s no give at all, but around the outer area of the lid I can press it down and there’s a moderate amount of give. Should I reprocess immediately or wait longer and then test?

    If it makes any difference I’m using Walmart Mainstays jars and lids. Perhaps it’s just because the lids seems a bit thinner than Ball and Kerr lids?

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