My Jars Didn’t Seal! What Happened?

July 13, 2018

We’ve all been there. You’re at the end of a canning project, the jars out of the canning pot and are cooling on the counter. As you clean up, you notice that there’s one jar that didn’t seal. Or worse yet, none of the jars have sealed. If this has happened to you, two questions probably popped to mind. Why did this happen and what can I do to fix it. Let’s tackle these one at a time.

Why did this happen?

  • It could be that your canning pot wasn’t at a full, rolling boil for the entire canning process. Without that full boil, it could be that the jars didn’t fully vent the oxygen in the headspace. Without a thorough venting, there won’t be enough of a pressure differential to cause the vacuum seal to form when the jars come out of the canner.
  • Another possibility is that there was a physical barrier to the seal forming. In most cases, this happens when you don’t wipe your rims completely, or some food particle gets pushed out of the jar during processing.
  • Sometimes the lids are to blame. Really old lids sometimes lose the ability to create a full seal. And of course, if you’re reusing lids, the chances that they will provide a high quality seal are very low.
  •  There was a chip or crack in the rim of your jar. This will prevent a seal every time. You can prevent this simply by carefully looking over your jars before filling and canning.
  • Improper headspace. Under or over filling your jars can sometimes cause the seal to fail.
  • Occasionally, the rings are the culprit. While it is important to only tighten to fingertip tight to allow the oxygen to vent, if you leave them too lose, that can cause a seal failure.

How to fix it?

The best way to handle jars that failed to seal depends on the product you’re dealing with and how many jars have failed. If you have just one or two jars that failed, the easiest thing to do is to put them in the fridge and eat or share them promptly. The reason for this is that to reprocess jars always results in some loss of product and quality.

When it comes to pickles, trying to reprocess them isn’t ideal, because any additional heat exposure will soften their texture. This is particularly true for cucumber pickles.

When it comes to jams and other sweet preserves, there are more options. If the entire batch has failed to seal, the best method is to open the jars, reheat the jam, prep the jars, use new lids, and reprocess.

If you have just one or two jars that didn’t seal and you don’t want to go with the refrigeration plan, there’s another way. Once the jars have cooled completely, put new lids on the jars (taking care to wipe the rims and make sure that you’re getting the rings tightened properly). Place those room temperature jars in a canning pot of cold water. Bring that pot of water to a boil slowly, so that the contents of the jars heat along with the water. Once it reaches a rolling boil, process as you always do. The jars should seal properly this time around.

 

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212 thoughts on "My Jars Didn’t Seal! What Happened?"

  • I canned quarts of wild game meat the other day and found 4 jars had not sealed. One went to stew right away and three I screwed the lid on tight and froze. Do you see a problem with freezing the three jars?
    Ed

  • When I put my jars in the cold water to boil do they have the lids on or off? Thanks and kind regards Melita

    1. They have the lids off at this stage. You’re just trying to warm the glass before you put your hot product inside.

  • I made jam using the certo recipe. I do not do a canning process. So if I add my jars of jam to cold water and boil them- do do lid off then once the ham is hot I add the lids and band again?

    1. I’m not sure I understand the question. But there’s no way to cheat the canning process. If you want them to be shelf stable, you need to empty the jars, reheat the jam and jars, refill, and process correctly.

  • i processed my jam as usual, but this time i left them in the hot water for 5 minutes before removing them. the lids didn’t pop nor is there an indentation in evidence. however, i can’t remove the lids with my fingers. they have the usual ping sound when i tap them with my finger. the lid is not flexible….i le. these are 1/2 pint jars of raspberry jam. do you think they are in fact sealed?

    1. Some lids don’t go as concave as others. As long as they feel solidly sealed, they should be fine.

  • I am new to canning and am wondering what to do if my pint jars won’t stay upright while canning. I have a very large canner (20 qt I think?) and the metal rack that fits inside the canner seems too big to hold pint jars easily (I think it’s made for quart jars only) so they tip somewhat while they’re in the water (like sideways about 30 degrees). I have tried my best to stand them upright but am still worried that the boiling water could displace them. Is this a problem? Should I find another rack that fits pint jars? Help would be appreciated.

    1. I would definitely look into getting a smaller rack. It’s not doing your jars any harm to be listing slightly, but it’s not great if they fall over completely. I really like the silicone rack that comes with the Ball Starter Kit. https://amzn.to/3YyLyBU

  • my wife and i have been canning dill pickles for years at 6300 elevation we moved 3 years ago to 3500 elev first year making 100 quarts of dill pickles was 100 % success the next 2 years was 100% failure we did not change how we make them but want to know what we did wrong. we do not hot water bath but pack the jars fill with the brine boiling quickly put lid on and ring to seal we have done this for years but the last 2 were 100%failure. we want to know what to do

  • I make English mustard by cooking recipe til thickened, boiling jars,& boiling lids. I simply then pour hot mustard in hot jars ,fill and place lid with ring on, let co and it seals. Yesterday half my batch didn’t seal. I’m not sure of the easiest way to reseal my mustard. Hoping you can help.

    1. The safest way is to open the jars, reheat the mustard, and refilling the jars. Do know that if you’re using Ball lids, they thickened the lids slightly a few years ago and that means that they don’t work well for the kind of sealing you are now doing. It would be best to process them in a boiling water bath canner.

  • I’m very new to canning so to start me off, I made a batch of strawberry jam a couple of months ago. I stored them in my basement pantry. I checked them about 2 weeks ago…well I just wanted to admire my handiwork…but when I tried to lift one of the jars up, the lid just lifted off. I threw out the jelly and the lid (I didn’t know how long it sat there unsealed) but kept the jar. I washed it in the dishwasher since then…it safe to reuse that jar for another canning project? Thanks in advance for your response.