# Pressure canning problem?



## nappy (Aug 17, 2003)

DH does most of the canning here and did so again this weekend. He canned stewed tomatoes from the frozen tomatoes which were thawed/heated up with the other ingredients before filling jars. After the required time for pressure canning was done, the heat was turned off under the canner. And then as pressure was coming down in the canner and before taking off the pressure regulator, he heard a couple "pops". Upon taking off the canner lid, he found two jars with both the lids and rings off, and consequently, a mess all over canner. We have checked the jar tops, rings and the lids' sealing compound but couldn't find the reason for the failure. The lids used were Golden Harvest brand though it doesn't seem that that would cause this. It did happen before with the last batch (only one jar) of those frozen/heated stewed tomatoes a couple months ago. He is wondering if the rings were tightened too much or too loosely, but he has never had a problem with both the lids and rings coming off. Any ideas or did I answer my own question?


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## suitcase_sally (Mar 20, 2006)

My opinion is that the rings were not tight enough. There were discussions this past summer where some people had a problem with the lids buckling due to the fact that the rings were screwed on too tight, thus the jar couldn't vent properly. A few other people have made mention of putting the rings on JUST BARELY FINGER TIGHT which ends up working the rings off during processing. All of my canning books say to tighten the jars FIRMLY TIGHT, which to me means about as tight as you would tighten your mayo jar before you put in back in the fridge. I have been canning for nearly 40 years and I have never had a lid buckle nor have I had a lid come off. Don't screw the lid down so tight that a child couldn't remove it - but don't make it so loose that you can remove it with three fingers, either. Just my experienced opinion.

edited to add: if he fills each jar and then puts a lids on after all the jars are filled, it's possible that he is getting ahead of himself and not making sure all the lids are tightened.


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## nappy (Aug 17, 2003)

He does one jar at a time...thanks for the reply though. He will probably tighten more firmly next time. I've noticed that in the past the rings nearly fall off as they're taken out of the canner so you are probably correct. He is strong so is compensating for that strength in the opposite direction!


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## suitcase_sally (Mar 20, 2006)

It's quite common for the rings to be loose after processing. When the vacuum forces the lids down there will be less pressure on the rings. Actually, I like it when that happens - I don't have to worry about accidently breaking a seal trying to loosen the rings.


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## judylou (Jun 19, 2009)

In addition to Sally's info the other possible cause is over-filled jars. Pressure causes the contents to swell, to expand thus the need for accurate head space. 

And if your frozen tomatoes were not thoroughly heated through before putting them in the jars, they will expand even more during processing. It is one of the reasons why when canning any foods that have been frozen, it needs to be well thawed first.


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## PixieLou (May 1, 2010)

Anecdotally - this past summer I found that a couple of my new silver rings were not compatible with some of my old canning jars. If I tightened them too much, they "popped" off the jar. Gold rings worked fine. The old jars were legitimate canning jars - though I can't remember which brand off the top of my head.


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## suitcase_sally (Mar 20, 2006)

That's good to know, PixieLou. It seems the new silver lids/rings are getting a bad reputation - deserved or not.


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## nappy (Aug 17, 2003)

Appreciate all your info. BTW, the frozen tomatoes were cooked (boiled) together with the onions, peppers and celery so I don't think that was the problem. He won't be doing any more frozen ones this year.


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## Paquebot (May 10, 2002)

Compatibility may be an issue. By that, I mean certain rings with certain jars. Like PixieLou, I've also recently encountered cases where just a bit more twist results in a plastic cap being in my hand. I also used to run into that years ago with some #63 jars but it was the fault of the jar and not the ring. But, also had the same experience as the OP did with last new Ball pints purchased for cream style corn. Blamed myself for following directions to the letter as nothing else would explain the "popped tops". But then, 2010 was the first that I've been involved with the "white metal" canning hardware. Flats are great with the forming dies adjusted just right and the sealant formula very good. Being involved in metal fabricating for about 27 years, I'm going to take a closer look at where Alltristra has gone wrong with latest lowering of standards. With jars being used here which are closing on 100 years old, doesn't take a genius to see where canning equipment has evolved.

Martin


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## suitcase_sally (Mar 20, 2006)

Martin, it's funny that you mentioned being involved with the metal fabricating industry. In my last post, I started to give my idea of what might have gone wrong in fabricating the rings, but deleted that paragraph because I didn't think anyone would know what I was talking about! (I'm a journeyman die maker). I'm thinking that the metal may not have the correct tension or the dies may have been breathing.


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## nappy (Aug 17, 2003)

This is getting interesting! Maybe the problem wasn't due to how firm the bands were screwed down. It will be irritating if changed designs can do this....could make for some exciting times when canning in the future. However, I could not find an obvious flaw in any of the canning products used.


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## MamaG (Sep 3, 2020)

i just had this exact scenario with my pressure canner! Two of the lids and bands completely came off with a ‘pop’ during the cooling stage. I was canning beef broth. Canning for years and never had this happen. After looking through some of the posts here, I went to have another look. I had 4 gem Jars and 3 jewel jars, and it was 2 of the jewel jars it happened to. The gem and jewel are only a hair width rim difference and generally considered comparable for gem bands. I guess with pressure canning, with all the different heating and cooling stages, the hairbreadth difference is just enough to make it a gamble as to if that will happen or not. I will reserve my jewel jars for water bath canning only and hope that fixes the problem. Maybe yours were jewel as well.


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