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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66 Responses to How to Check That Your Seal is Good

  1. 1
    jess says:

    It’s not a question, but more of a request: I was always very intimidated by canning, because the books made it seem complex and error-prone. (Especially considering the threats of botulism!) When I canned applesauce, I was surprised by how easy it was. What about a post that emphasizes the ease of canning and breaks down the fear?

    It’s possible you already have such a post in the backlogs.

  2. 2
    MK says:

    Having a bad seal isn’t a big deal – it’s a minor canning bummer but easily fixed. After the jars cool, always take the bands off. It will be obvious if the lid is loose. If it becomes loose over time, mold will grow on top and that’s a real good way to know. It looks icky, but it’s not botulism – botulism can’t grow in a jar with a bad seal. Oxygen kills botulism. Speaking of botulism, it’s very rare. Read my blog post here about it:

    http://motherskitchen.blogspot.com/2008/08/safety-of-home-canning.html

    Dining out at a restaurant is more hazardous to your health than home canning! Hope this helps!

  3. 3
    deb says:

    I too made applesauce recently. All the jars sealed very well, in a couple the applesauce came up and out of the jar a bit before sealing. I imagine there is applesauce caught in the lid seal area. I can pick the jars up by the lid edge, so they are very tight, but are they really ok?

  4. 4
    Jaime Lenet says:

    I was wondering if you have any handy tips about adjusting processing time if using a different sized jar than called for in a recipe. Is there a rule of thumb on this?

    Thanks!

    • 4.1
      Marisa says:

      Yes. If the recipe gives you processing time for pints, that processing time is good for 12 ounce, half pint, 6 ounce, and quarter pint jars. If you’re increasing the size of the jar, you add five minutes to the processing time.

  5. 5
    Tracy says:

    Two questions:
    1. Tiny bubbles appeared in my applesauce a day or so after canning. Is this normal?
    2. Got any ideas for fresh cranberries?

    Thanks!

  6. 6
    Elaine says:

    I know lids can only be used once if sealed onto a jar. But if I heat up lids in hot water to prepare them for use, then don’t end up using them because my recipe didn’t fill as many jars as I expected, can I cool those lids and use them another time?

    • 6.1
      Erin says:

      You can use the lids over and over again.

      • Marisa says:

        Erin, it’s actually not advised to reuse the lids. Jars and rings, yes. Lids, no.

        • Lorrie says:

          Soooo, with regard to the original question, can you still use a lid that was heated but not sealed onto a jar?

          • Marisa says:

            You can use a lid if it was simmered in preparation for use, but then ended up being unnecessary. As long as it wasn’t applied to a jar and run through a boiling water bath canner, it is still good.

          • teresa says:

            I always just let them cool and put them back in the box to use next time. I never “re-use” them.

      • Beverly says:

        You cannot use lids over and over again. Rings and jars can be used again, but not the lids. The lid is a one time use item. If you are not sure, call Jarden to verify what I am telling you.

        If they were just simmered and not actually put through the BWB, you can use later.

  7. 7
    anduin says:

    What in the world is this a picture of? It looks like it says “FisucatisFun”…???

  8. 8
    Eleanor says:

    1) I am curious about the processing time changes for changed bottle size, too. For example, I made the Octoberfest Beer Mustard in the big Ball Canning Book. The recipe calls for 4-oz jars, so that is what I made. But, I would rather make 8-oz jars (for gift giving). But, I didn’t know what would be safe.

    2) I made the Ball Canning Book recipe for curried apple chutney, but got only 7 quarts plus one 4-oz jar (not the expected 10 quarts). So, it is more like curried raisin chutney (still tastes good). I figure that it will be ok, since the seals are all good AND it has enough vinegar in it to make the 10-quarts. What do you think? I could throw it out and try again.

    3) Great cranberry recipe: try the Cranberry Chutney (includes apples) in the Ball Canning Book. It smelled odd at first, but as it simmered, it developed a great aroma. Also, it tastes terrific! Though it might be an intersting addition to Thanksgiving dinner. :)

    • 8.1
      Marisa says:

      1. If the recipe specified 4 ounce jars, it’s best to use them.
      2. Totally safe.
      3. I’ll have to look for that one!

  9. 9
    lo says:

    I wandered over here at the recommendation of a friend — and boy, am I glad that I did. This is like HEAVEN for the skeered little canner girl in me!

    I have fond memories of waiting for my mom’s jars to “ping” after a big canning project. She always made it look so easy! But, I’ve suffered pretty seriously from “canning anxiety” (see comment #1: I think we’re psychic sisters). So, my question is — how do I can my own creations? That escabeche I love so much? The salsa I can’t get enough of? Aren’t there worries over having ENOUGH acid or somesuch? What about my favorite marinara?

    My over-analytical brain always wins out and keeps me from moving forward with canning.

  10. 10
    Liz says:

    A student in one of my canning classes suggested removing the ring and turning the jar upside down- A gutsy move, but I suppose that’s one way to check a seal!!

    As for adjusting recipes for different jar sizes, the general rule is that you can always use a smaller jar and process for the same amount of time (i.e. process for the full pint time even with 1/2 pint jars)…but there’s no way to know the safe time for a larger jar without a tested recipe for that size jar. Sometimes I’ll just look in another book with safe, tested recipes and happen to find times for larger jars. Otherwise, I just deal with jars that are smaller than I’d like and know that I’ll live to eat them all :)

  11. 11
    Stacy says:

    I have the same question as Elaine–I’m always heating up too many lids, then I’m not sure if I can reuse them… Would love to know! I’d also love to hear that elusive “ping” sometime!

  12. 12
    Jessica Roberts says:

    I was just told that if a canning recipe calls for lemon juice I should always use bottled lemon juice for acidity control. Is that true? I’ve always just used real lemons and wasn’t aware that was a problem.

  13. 13
    Rcakewalk says:

    My Mom always taught me to listen for the “pop” especially on low acid jars like tomatoes.

    I second Lo’s question, how do you figure the times on home creations, and do you have to use a pressure canner instead of a water bath in some cases?

    • 13.1
      Beverly says:

      You do not figure the times on home creations because you do not can home creations.
      Get the Ball Blue Book of Canning and learn all about canning. Use approved recipes and follow them exactly.

  14. 14
    MK says:

    You can reuse the lids that you’ve heated once – I checked with the extension service on that. You just can’t reuse lids that have been sealed on a jar.

  15. 15
    Kathy says:

    A few thoughts and helpful hints…

    As for testing for a seal, I always test the “button” on the top of the lid. Although, sometimes it will seal and then lose it’s seal (rarely for me) and those jars either get used right away or the contents tossed.

    Lids can be heated, cooled, and reused. Remember, you want to heat the lids prior to use, but do not use boiling/simmering water as that will melt or ruin the rubber ring under the lid.

    As Liz stated, you can always use a smaller jar and process for the same time, but you cannot go LARGER if the recipe does not call for it.

    Bottled lemon juice should always be used as it has a tested and consistent level of acidity. Fresh lemons actually change in acidity levels depending on the variety…some Meyer Lemons are actually sweet!

    Lastly, remember there are cooking recipes and there are canning recipes…they are NOT one in the same! Always use a reliable and TESTED recipe from a reliable source. Very few people who are aware of the safety guidelines regarding home preserving “make up” their own recipes.

    Boiling water bath recipes and pressure canning recipes are not one in the same and have different standards and requirements due to ph and acidity levels in the food.

  16. 16
    Donna says:

    We just canned applesauce as well over the weekend. Not nearly as intimidating as I thought. It was very cool to hear the pop when they sealed.

  17. 17
    MissJubilee says:

    I have 2 questions and a suggestion.

    I’ve been canning applesauce in big jars, and when I’m simmering the apples for the sauce, I put in about 3/4 to 1 cup of extra apple juice. Then I ladle it out before blenderizing the sauce. I’ve been canning the liquid that I ladle out in small jars as “cider concentrate” with a bit of orange rind studded with cloves, a piece of cinnamon, a slightly-bruised nutmeg, and a slice of candied ginger. “Just add to regular apple juice and heat” is the idea. I’m hoping to give them to friends in my old city when I visit this Christmas since I’m not there to make the cider mix fresh for them the rest of the fall/winter. So, that recipe is kind of my “suggestion,” but also leads to my questions:

    Is it safe to can those things, do you know? Liquid plus nut, stick, cloves, peel, ginger? I hope none of them overwhelms the flavor of the others, too. I boiled the small jars of liquid for about 20 minutes, just guessing that would be safe; there was lemon juice in with the apples as well so it should be acidic enough, I hope.

    And, second question is about sealing: I didn’t have time to cook AND can on the same day, so I refrigerated the full cans for a day or two or three and then re-heated the jars (without their metal lids) in the microwave before putting the lids back on and putting them in the about-to-boil water. So, I tightened the lids a little extra, figuring they were cold and not hot and thus not as expanded as they should be, but I think it was still not tight enough, because those little jars didn’t “pop.” When I went to check on them and touched the lids with my finger to check, THEN they popped and stayed down as soon as my finger touched them (before I pushed down, just touched them), and then I tightened the lids which seemed rather loose. So, have you ever experience this, and do you think it’s safe, since they did eventually seal?

    The kicker is, these are Quattro Stagioni jars, the only kind I can get here, and they have one-piece lids, and the shop doesn’t sell lids by themselves, so if I have to re-can them, I have to buy whole new jars. These little ones have 56mm lids, so they’re smaller than the standard American jar lid sizes. :S (The applesauce jars are 70 and 86mm, which correspond to “standard” and “wide-mouth” sizes – guess what I’m asking my family in the US for for Christmas?)

    • 17.1
      Beverly says:

      No, no and no. Approved and tested recipes only. Cook and can on the same day only. Don’t touch the seals for 24 hours.

  18. 18
    Laura says:

    It’s also good to store jars with no rings on them. That way it’s obvious which seals are bad, or go bad later.

  19. 19

    [...] in the bottom of the pot to keep the jars from bumping and cracking) Once the jars have cooled, check the seal and reprocess any unsealed jars or use refrigerate and use those jars immediately. Store jars [...]

  20. 20
    kaela says:

    I also have a question about Quattro Stagioni jars; have you ever used these? I bought a few up in Maine over Thanksgiving, just to try them out as they are pretty and I’m getting quite sick of the quilted Ball jars (they only kind I can find near me).

    I’ve tried out one small (.15 liter, about 4 oz) and one half-pint size Quattro Stagioni; so far, neither of them have sealed and one opened up and let canning water into the cranberry sauce while processing (ewww). So, it seems I didn’t tighten that one enough but – any recommendations? The instructions that come with them are somewhat bizarre and I wonder at translation issues; you are supposed to fill jars with “product at room temperature” (I assume the jars are not hot either). Then you are supposed to put the jars into the canner, cover with lukewarm water and bring it all to a boil and process (for whatever time your recipe calls for) then leave the jars in the canner until completely cool. (They also suggest “consumption after at least 60 days.” I thought it was a translation error, but it says the same thing in French; wait at least 60 days until eating. Strange!)

    The half-pint size take a regular-mouth Ball jar lid so I may just try that next, but wondered if you had any tips.

    Thanks!
    Kaela

  21. 21
    Kate says:

    I have been pickling and making jam for years, and I was learned from my grandmother and mother…so lots of experience there. I re-use my lids each year UNLESS they become stained or just don’t look right. The re-used lids seal fine and no one in my huge family has ever gotten sick. I am a big believer of re-cycling whenever possible!
    :)

  22. 22
    Kara says:

    Thanks for the great info. I canned some salsa and right when the cans came out after processing and were still piping hot, I touched the top of one of the lids (bad, I know!) and manually popped it in. I hardly put any pressure on it and it went right in. I am almost sure it would have done it on it’s own as it cooled. My question: does the seal count?

  23. 23
    Jane says:

    I too just used Quattro Stagioni jars – I think they were half pint and I made a lot of plum jam. Perhaps I did not follow their instructions – Instead, I did as i had done with the Ball jars and immersed them when full of hot jam into the boiling water. I saw 3 of 7 did not pop – the little button on top was not depressed but raised, and so i decided to process them again – and to be safe did 15 minutes. I heard all pop when they came out. however, there were three that looked like the button was up this morning and i found the lids loose. I had put them in with loose enough lids – (finger tight as some say though that term is very unclear to me) – and perhaps i was supposed to screw them on very tight? If not, do they tighten up while being processed???

    Now i have been looking for hours today for answers on how to properly use these jars and have them seal. I am hoping to get answers here. I have refrigerated the jars that did not seal, but could not eat all that jam – maybe in a month :) So, do i have to use new lids? buy more lids? and reprocess? Is that safe?

    How much time can pass before i reprocess if safe? They have been in refrigerator except for the first night when cooling. I did not let these jars cool down with water as some other posters mentioned; I took them out after 15 minutes from the canner.

    In addition, I now have 2 flats of Damson Plums, plus big bowls of Flavor King and Elephant Hearts macerating (overly-eager i guess having just discovered how to can), and am wondering if i need to return to Ball or other jars as I had no problem with any of them. Please advise – I don’t want to lose all my good plums….

    Are we just not taking the correct steps with these jars? Should I screw on the lids very tightly before immersing? Should the water be luke-warm when immersing? Boil for 10 minutes or as recipe indicates – and then let them cool in water? If so for how long? Does anyone use these successfully and if so can you post in detail what steps you take – and with those jars that do not seal.

    There must be many of you who know how to process these jars without having this happen? I’d love to make my first batch of Damson Jam in them! I ordered the Damsons from a local farmer and picked them up today – so would love some help with these jars till my Weck order arrives. (Hopefully I get the knack of using those!) Thanks!

  24. 24
    Rachel says:

    I did test #3 to the applesauce I processed yesterday and I was able to lift the lid with the jar attached for a moment, but then it popped off and spilled all over my counter. Would that been enough of a seal?

    • 24.1
      Marisa says:

      Rachel, that wouldn’t have been enough of a seal. It should hold tight no matter what. And in the future, you only need to lift it about half an inch, or so. :)

  25. 25
    Kris says:

    Question;
    I opened a sealed home-canned jar of my tomato sauce with my nail and there was no pop. Is this bad. I thought it smelled fine and am cooking with it now. Any suggestions?

    • 25.1
      Marisa says:

      Kris, if the jar did not appear to be well-sealed upon opening, it’s probably not a good idea to eat it.

  26. 26
    Kristin says:

    Am I the only one who is scared to pick my jars up by the lid? I suppose I shouldn’t be. It just sounds like tempting fate!

    Also, Marisa, in case this comment brings you back to this thread, you have some interesting unanswered questions above, such as, what is in this photo with the interesting name on the lid?

    Thanks for all your info.

    • 26.1
      Marisa says:

      Kristin, if you wait until the jars are fully cooled, the seal should be so strong that it will hold tight and fast. Also, you’re not waving it around your kitchen. You’re picking it up an inch for a second or too.

  27. 27
    teddy says:

    i made heirloom tomato jam today and canned for the first time…i followed instructions from a friend who did not tell me NOT to press on the top of the lids when the jars came out of the 15 minutes boiling process to finish the jarring. i was so excited..i wanted to see if they had “popped”…well, i pushed on each one while they were still hot and found they had all a little give in them… and then came to your website where i read, let them sit..so i did..and i heard a few pops in the kitchen ( which i must say brought a smile to my face)..i only heard two..but when i went back about twenty minutes later and i pressed on them all again to see which one had popped and they had all gotten tight. with no give…so now i don’t know if they are good or bad or if i pressed the air out and there is no seal…what do you think?

    • 27.1
      Marisa says:

      You didn’t push the air out of the jars. If the jars sealed, the seals are good. You can’t force a jar to seal if it’s not going to. So don’t worry about it.

  28. 28

    […] 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 […]

  29. 29
    Cathi says:

    I was canning pickles and as soon as the come out of the water bath I touched the top of one. It immediately pinged down but I am afraid it was because I pushed on it a little. It does not go up and down when pushed but is this a valid seal? I’m a little concerned. I didn’t touch the two other jars and they sealed perfectly. What do I do?

  30. 30
    Mia says:

    I see that a lot of people say that you have to use lemon juice in the bottle. Part of the reason that I’m home canning is that I’m allergic to the juice in the bottle. (It contains sulfites, and along with other stuff in commercial jams/jelly, it makes my tongue swell and my throat swell). any suggestions for testing acidity?

    TIA

  31. 31
    Carol says:

    So, if you can’t touch or test the seals for 24 hrs, how do you immediately refrigerate any jars that didn’t seal?
    Also, I have always tested the seals by using my fingernails and seeing if I can lift the lid. In the latest round, 2 of 3 jars the lids lifted, but there was a “sucking” sound. The “buttons” on the lids had gone down, but I didn’t HEAR the popping, and when I pushed on the lids they didn’t move. Were the jars really sealed? The other jars would not open with my nails. Am I inadvertently opening sealed jars?

  32. 32
    Eleanor says:

    I have kind of a silly question.. Will checking the lids too early by pressing on them affect the sealing process? I got a little excited, and pushed a couple before they cooled..

  33. 33
    Steph says:

    I canned applesauce a month ago. Today I happened to hear one of them pop and when I checked, the seal was broken. Is it safe to assume that it just popped and put it the fridge to eat it? Or should I just throw it away?

  34. 34

    […] food safety of your gift! If you’re feeling unsure or worried, check out this awesome post on how to check if your seal is good by the small batch canning queen, Marisa […]

  35. 35
    Anna says:

    I just canned apple butter for the first time. The lids have drops of water attached to the bottom side of them. I’m guessing due to steam from the apple butter or from putting the lids on the jars when they were slightly wet to help the seal. Is this okay?

    Also, do you recommend wiping the rims of the jars with a wet cloth to help them seal or taking the lids directly out of the boiling water and putting them on the jars wet? We originally tried to dry off the lids and then put them on the jars, but none of the lids sealed properly that way during our first 3 batches of apple butter. We are going to boil the apple butter again tomorrow night and then try the canning process again. Hoping to do it right this time around!

    Thanks!

    • 35.1
      Marisa says:

      Anna, don’t worry about the small amount of condensation in the jars. If the jars are sealed, it won’t do any harm to the products. I recommend wiping the rims of the jars prior to putting the lids on. You to this to insure that there aren’t any food particles on the jars that could compromise the seal. You don’t need to wipe the lids off before applying them to the jars, though. They should be hot enough that the water will evaporate readily when you pull them out of the simmering pot. If you’re having sealing problems, it could be that you’re not leaving enough headspace. Because it’s so dense, apply butter needs a generous 3/4 inch of headspace to seal properly.

  36. 36
    Amanda says:

    I have a question about pickling. I made pickled peppers and did a water bath for 15 min. The jars were sealed and then became unsealed so I used new lids and reboiled them. Those also sealed and then unsealed so I pushed on the button and tried screwing them tighter. After that they did seal, with the little button down. I let them cool a little and took off the rings. I pulled on the tops and they stayed. They seem like they are fine and that they are sealed but I am nervous that they aren’t safe. If they are sealed and the button is down, should I worry? Thanks!

    • 36.1
      Marisa says:

      Amanda, I’m a little confused. How long did the jars sit before they unsealed? I’m not sure why they would be sealed and then unsealed like that. Unfortunately, after a couple rounds of water bath, the texture of those pickles is not going to be good.

  37. 37
    Glenda says:

    How long does it take for pickles to seal the jar? I made 14 day pickles that do not require a waterbath. Just heat the pickling mixture and put in the jars? Many thanks for any suggestions.

    • 37.1
      Marisa says:

      I have no experience with 14 day pickles and don’t recommend any process that has you skip the waterbath.

  38. 38
    Stephanie says:

    I have a question about jam that’s been in storage. I just took a couple of jars out and the button is no longer sucked down, but the lids are tight. I am quite sure the button was down when I put them in the cellar. Any idea why this happened and if they are safe?

    • 38.1
      Marisa says:

      Press up and down on the lids. Do they wiggle? If so, the vacuum is no good and the contents should be discarded. Seals go bad for any number of reasons.

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