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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152 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?

    • 63.1
      Marisa says:

      All that matters is if the center is down and the lid stays adhered once the ring is removed.

      • Melissa says:

        I made 8 half pint jars of spiced apple butter tonight (water bath). After 1 hour, 6 had popped and sealed while 2 didn’t. I lightly tapped the top of the two that hadn’t sealed yet and they went down and stayed down. If I need to re process those 2 that’s totally fine… The only thing is that I have a pantry full of canned goods that I have “helped along” by popping them down myself… Dun dun dunnnnn…. Am I totally screwed?! I didn’t know about the 24 hour rule until tonight!

  14. 64
    Nicolee Coles says:

    how long do I need to let jars seal. I made relish. The relish was slightly cooled when I put in jars. Brand new jars and lids. Rims checked and cleaned. Jars are not sealing after 20 minutes or so. Should I be worried and can I reseal the next day in hot water?? Help!

    • 64.1
      Marisa says:

      The relish should have been piping hot when it went into the jars. If the jars still haven’t sealed, that could be part of the problem. You always give jars at least an hour before you start freaking out about the seals, but if you do need to redo the seals, you need to empty all the jars into a saucepan, reheat the relish, and then follow these instructions starting at step 8. http://foodinjars.com/2011/08/canning-101-how-to-save-runny-jam/

      • C.D. Lamberth says:

        I just put up a half gallon of cowboy candy and was getting anxious thay I hadn’t heard the lid seal after an hour or so. In pushing down on the lid my heart sank as it moved with ease. I removed the ring, and found that, somehow, I’d used two lids! In testing with the pick-up procedure, however, the bottom lid held fast in lifting a half gallon jar of peppers and syrup. It also could not be depressed, so with much relief I returned the ring and placed it on a shelf. I’ll, of course, retest in 24 hours.

  15. 65
    Leslie says:

    okay, so I made canned tomatoes. the lids seem to be sealed good and I can lift from lid and it all staying on good. BUT most jars have floating Tomatoes and some have tomatoes that sunk and taking up the whole jar. What does that mean???? are they sealed? and ready for storage? Thank you!

  16. 66
    Jules says:

    Hey there – I LOVE YOUR SITE! This is my first year jamming and you’re right – it’s wonderful!!!
    I have a jar that I made and sealed a week ago. This morning I realized that the center had popped back up…I thought I was seeing things so I pushed it, and it stayed in easily and isn’t popping back up. When I try test 3, and hold the jar by the lid – it’s definitely still totally sealed. What do you recommend? This seems bizarre – but maybe it’s just on it’s way to spoiling? I put it in the fridge for now. I read through the other comments but didn’t find anything about this specific scenario… Thank you hugely for following your passion here – and sharing it! This is wonderful!!!

    • 66.1
      Marisa says:

      If doesn’t matter of the sealing compound continues to hold. If there’s no reliable vacuum seal, that jar is suspect.

  17. 67
    lee says:

    So, I have a batch of blackberry jam that I canned during the summer, which I processed in a water bath, and all the jars sealed correctly. I think. The lids are very firmly on, and all the buttons went down and stayed down without my touching them. The rims are on very loosely, so they’re not holding the lids down. The thing is, when I opened a jar, I broke the seal with a bottle opener, and the lid came off with a sucking sound (indicating a seal), but the button in the center of the lid didn’t pop back up. I tried opening a second jar and the same thing happened. Is this a problem? The buttons will pop up if I tap them with my fingernail. The jars are stored in a very cold pantry — could the cold be making the lids stiff? Do you think the jam is okay to eat?

  18. 68
    Joyce says:

    I just made cranberry-Apple butter and one of my jars didnt seal. Since I left them overnight, it’s completely cooled. Can I reprocess cold or do I need to reheat the contents and jars and start over?

    • 68.1
      Marisa says:

      If you only have one jar that didn’t seal, here’s what you do. Remove the lid and ring. Wipe the rim and put a new lid on the jar. Place the jar in a pot and cover it fully with cold tap water. Set the pot on the stove over medium heat and slowly bring it back up to a boil. Once it’s at a rolling boil, process for the amount of time instructed by the recipe, plus five minutes.

  19. 69
    Mark Mota says:

    We use it for freezing food, leftovers and I package drugs, select foods and supplies for storage. You will not regret this purchase. A lot better than mylar bag storage.

  20. 70
    Patrick says:

    Yesterday, I made my first attempt at canning to preserve a too-large batch of salsa verde. I have four jars and while three seem to have a good seal and pass the “tap” test with a tinny sound, one has a dull thunk. The one with the dull thunk seems to otherwise be sealed (although I will recheck this now that it has had more time to sit).
    I’ve read online that the dull thunk sound can be because the seal is poor or food is touching the lid. I’m also working out of the Ball “Home Preserving” book, but it doesn’t really address this test for seal quality, which leads me to believe that maybe it’s not a perfect test.

    Is it possible to still have an adequate seal with the dull ‘thunk’ sound?
    If not, can I get away with reprocessing the jar, or should I throw it out since it has been unrefrigerated for 24hrs?
    Thanks!

    • 70.1
      Marisa says:

      The sound of the lid isn’t an accurate way to test for seal. Do this instead. Remove the rings, grasp the edges of the lid and lift the jar an inch. If the lid stays firmly sealed, the seal is good. If you feel it starting to give, you can either reprocess it or just refrigerate it and use it first. The fact that it sat out for 24 is fine. That’s not enough time to have spoilage in a high acid preserve.

      • Patrick says:

        Lifted them up by the lid and they all seem to have sealed!
        After taking the rings off I could clearly see the problem jar had salsa all the way up to the lid. I made sure they all had 1/2″ of head space before putting the lid on, so I’m not entirely sure what caused the difference with that one.
        For future reference, is it possible that air bubbles could have caused it? I did notice that I could see some air pockets in the salsa in the problem jar while the others did not.

        Thanks for the help!

        • Marisa says:

          Sometimes salsa expands a little in the jar. The air bubbles shouldn’t have caused the expansion, though.

  21. 71
    Julie Holt says:

    I made 2 batches of jam, the first batch of raspberry I put the liquid pectin in too soon, I put it in the beginning, Is it ruined? They all sealed?
    Them I tried a second batch of blackberry jam and I did not read the don’t tilt or move for 24 hours, are they o.k.? Everything sealed but I was cleaning the jars moving them around , old lady brain fart!
    Do you think they will be o.k. I don’t want anyone getting ill.
    Thank you

    • 71.1
      Marisa says:

      Julie, adding the pectin at the wrong time or moving the jars won’t make a batch of jam safe or unsafe. As long as you didn’t change the ingredients, it’s going to be okay. The only thing that could make that jam unsafe is if you added low acid ingredients like tomatoes or mango. The pectin error and moving them might impact the finished set a little bit, but the’s the only problem that might possibly occur.

  22. 72
    Sarah says:

    it looks as though some jam in my jars bubbled up during processing and is touching the lid. Is this a problem if all other checks are okay? Also there are little bubbles in the strawberries.

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  1. Canning Salsa | Eva Wasney - March 30, 2015

    […] 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 […]

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