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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188 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.

  23. 73
    John says:

    i just made 10 jars of pickles but during the boiling 7 of them popped up forming creases in the lid. If I turn them upside down (after they cool, 24 hrs) and the seal doesn’t leak are they still good? or do I need to put them in the fridge and eat them within a couple of weeks?

    • 73.1
      Marisa says:

      If all those lids creased, it sounds like you overtightened your rings. The air in the jars couldn’t escape naturally and so bent the lid in its efforts to vent. None of those jars are shelf stable.

  24. 74
    john says:

    If a lid on a pickle jar creases during boil but does not leak when you turn it over the next day is it still good or do you have to refrigerate right away.

    • 74.1
      Marisa says:

      If the lid buckles, bends, or creases in any way, that jar is not shelf stable and needs to be refrigerated.

  25. 75
    Elizabeth Lee says:

    Hi Marisa,
    Made blueberry jam about three weeks ago using the water bath method. All the jars were sealed but I noticed that in some of the jars that the jam is moving around a bit. Its not loose, its solid but when I turned it over the whole lump of jam was able to fall down in one solid mass. Is my jam still safe to eat?

  26. 76
    anne says:

    I made pepper jelly. the cans sealed because they are concave and i held them by the lids like you said. However there is some sticky stuff on the outside of the jar. Is this a problem, are they safe to eat? The lid appears to be sealed.

  27. 77
    Elaine says:

    When I took my salsa out, I gently wiped water off the top and when I did that it made them pop down. Is that ok, or should I have left them alone

  28. 78
    Carolyn says:

    Novice canner here. I was under the impression that once the jars were sealed the food inside would not slosh around. I just canned some carrot soup (ball recipe) and the contents of the jar move around when tipped. Normal?

  29. 79
    Jennifer Smith says:

    Hello! I am new to canning and just made first batch (med-hot peppers!). Previously I took a class and made jam and then my father in law taught me how to can peppers. In the class, while sealing the jars, the instructor held the lid down (depressed the button) while she tightened the ring. I do not remember my father in law doing this. So I have two different methods of sealing rings. Is one right or wrong? Will both ways properly seal the jars? Thank you so much!

    • 79.1
      Marisa says:

      I would imagine that the teacher who held the lid down while tightening the rings was doing it simply to keep the lid aligned. Doing that has no impact on whether the jar seals or not. The thing that makes the jar seal is the pressure differential that is caused after you remove the jar from the canning pot.

  30. 80
    Denice says:

    Hello. I’m totally new to canning and want to know if I can I reuse the lids or should I buy new?

  31. 81
    Carmella says:

    Hi. I was actually going to leave a comment on your http://foodinjars.com/2010/08/canning-101-why-you-shouldnt-can-like-your-grandmother-did/ post but there was no comment box, so I apologize if it’s not completely relevant to this post.

    I made some jam for the first time yesterday. I don’t have a proper pot to give a hot bath so I used a pasta pot that has an insert which can be easily removed. While the jars were all submerged, the water wasn’t reaching quite 1″ above them in the process. Do you think that the hot bath was still effective?

    Thanks in advance!

    • 81.1
      Marisa says:

      I closed the comments on that post because it was getting out of hand. As long as the jars remain covered with water throughout the canning process, you’re good.

  32. 82
    Mg says:

    Hi. I made pickles and some lids didnt properly seal. I see in previous posts to put them in fridge. Hiw long are they ok to keep in fridge

  33. 83

    […] to cool completely before handling. I usually leave them until the following morning. Remove rings, check for seal , and wipe the ring and the jar clean. They may have some salty residue from your brine. It is […]

  34. 84
    Sarah says:

    Hi. My lids have no give when I push on them. However, the sound when I tap with a spoon is dull. I canned nectarine halves and they floated to the top. How reliable is the spoon tap sound method?

    • 84.1
      Marisa says:

      The sound doesn’t matter. You just want the lids to be solid and concave. Nectarines often float to the top. It sounds like your jars are fine to me.

  35. 85
    Cindy says:

    Hi!
    I tried canning salsa today and all my jars sealed but I have air bubbles in the jars… What do I do?

  36. 86
    April says:

    I didn’t know about the 24 hour rule until I found your site. Super helpful info – thanks for that! 🙂 I made grape jelly for the first time tonight. Followed the Sure-Jell recipe to the letter. I heard a sound of a ping and thought “oh no! my jar unsealed!” (can you tell I’m a rookie?!) I checked, and it seemed unsealed…but now it has “resealed.” Should I just leave them alone and check after 24 hours? Is it possible they are still ok?

  37. 87
    crystalyn says:

    hi, if properly canned jars pass the 3 lid sealing tests mentioned above and become “magically unsealed” a month later-what happened? some of my peaches and tomatoes have been tossed out because of random spoilage.

    • 87.1
      Marisa says:

      I don’t really know what happened beyond the fact that they spoiled. It happens. Are you doing the boiling water bath process for the proper amount of time?

  38. 88
    Marie says:

    I just canned beets they sealed good and have been sealed for a month and just unsealed why would this happen

  39. 89
    Johanna says:

    Canned 10 pints of dilly beans last weekend. 8 sealed quickly, 2 did not. Once jars were cool, but less than 24 hours later, placed the 2 unsealed jars in the fridge. A few days later, I discovered that both jars in the fridge had sealed. Are these good now for long-term storage or should I keep them in the fridge and eat soon?

    • 89.1
      Marisa says:

      My feeling is if you did a proper boiling water bath and the jars have a good seal, they can be stored in the pantry.

  40. 90
    Shannon Foor says:

    I have a question, I made up some tomotoes and they all sealed great. I went to use two of the jars today and i was able to remove the lids with my hands. Is that normal? They all pasted the tests youve stated. Just most of my lids dont come of that easy. Thanks

  41. 91
    Luke Yancey says:

    I’ve never heard of your third tip of unscrewing the band and attempting to pick up the jar holding nothing but the lid. My mom frequently cans and we eat a lot of the fruit when I visit. These are all really great tips to make sure that it is still good!

Trackbacks/Pingbacks

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