Popping and Canning Jars: What it Means

At-home canning is one of the best ways to preserve all kinds of food. It’s a valuable skill and also a fun pastime. But I’ve said before that it is just as much art as it is science, and even with the most detailed guides there’s always going to be things that happen—unexpected things that come up. Some of them will leave you scratching your head and wondering if your food is okay!

Great example: popping noises coming from your jar. It’s a common phenomenon when you are taking your jars out of the canner, but it can also happen after they’ve been sitting on the counter cooling for a while.

Naturally, most folks suspect something has gone wrong with the lid. Let me reassure you that that isn’t necessarily the case!

Popping is a normal part of canning, but you must know how to check your jars for a good seal when it happens. Keep reading, and I’ll tell you everything you need to know…

First Things First: Popping Isn’t Bad!

I’ve got to make sure this is perfectly clear because I hear it come up over and over again, and I fear beginning canners are throwing out good food: if you hear a pop at any point after the canning process is completed, that does not mean that the food has gone bad or that the seal has failed. Not necessarily, anyway!

In fact, you can basically disregard any popping you hear because you’ve still got to do your due diligence when checking your jars prior to putting them away. We’ll talk more about that later, and I’ll give you a step-by-step, foolproof process to follow…

For now, just learn to ignore any popping you hear until it is time to check the lids themselves.

Jars Might Pop When You First Take Them Out of the Canner

One of the most common occurrences of popping is when you first take your jars out of the canner. In my experience, your smaller jars, like pints and quarts, are a lot more likely to do this.

They might pop when you still have them in the tongs, once air hits them, or right after you set them down on the towel or cutting board to start cooling down. You may also hear a sort of crinkling sound as the metal of the lids or bands starts to contract.

This is totally okay! Just focus on what you’re doing and ignore it…

They Might Pop Much Later

The next occurrence when you are likely to hear popping is after your jars have started to cool down significantly post-removal.

Often this will take place anywhere from 6 to 12 hours after setting them aside, and sometimes much later, between 12 and 18 hours. This is also when you are most likely going to hear your larger jars pop.

Once again, this is normal. I know it can be disconcerting to hear that loud pop or ding hours after you have finished with the canning process, but it does not mean that anything has gone wrong.

If you are following instructions for canning any given food specifically, you should have a timetable on when you need to check your jar lids for a good seal after they have cooled down completely. Once that amount of time has elapsed, it’s time to find out the truth.

Don’t Disturb the Lids Until the Jars Have Totally Cooled!

Here’s another critical tip for you: I understand that popping anxiety often leads folks to start messing with and checking their jar lids as soon as they get them out of the canner and they are cool enough to touch at all.

This is a huge mistake! Don’t mess with the jar bands or the lids at all until they’ve cooled down completely. Doing so is likely to induce a seal failure and ruin your hard work! Whether they pop or not, set those jars aside until they are cool.

Will Jars Always Pop?

No, not always. They will, commonly, but some lids just won’t make a popping sound whether they have sealed properly or not. That’s the other reason why I advise people to ignore the popping totally: we can’t rely on it as an indicator of a sealed lid and, ergo, safe food.

The Right Way to Check for a Good Seal

The good news is that you don’t need to try and decipher whether popping is good or bad. We have a procedure that will tell us pretty much without fail!

Here’s what to do: Once your jars have cooled down completely to room temperature, something that usually takes between 12 and 18 hours but sometimes up to 24, you want to press on the lid gently with a fingertip; the lid should be down, flat, and taut. It should not move, bounce, or make a sound.

If the lid is still good to go, remove the band and then carefully, gently lift the jar straight up off of the counter, holding it just by the edges of the lid. You only need to lift it up about an inch, like so:

You should not feel any movement, you should not hear a pop or hissing or bubbling, and the lid should stay flat and down as it was.

If the jar passes that test, you can rest assured that it is properly sealed and ready for storage. Any jars that don’t pass should either be opened and eaten within a few days or reprocessed in a new jar with a new lid to reseal them.