Can you reprocess jars that don’t seal?

Last Updated on January 18, 2021 by cmoarz

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So, Can you reprocess jars that don’t seal?

We all want to save as much money as possible and one of the best ways of doing that is to get as much use out of something we already own rather than buying something new that can fit the same purpose.

Unfortunately that isn’t always the best idea, and that is doubly so for reprocessing jars.

Well, to be more clear, the glass jars themselves are fine to reuse as many times as you wish, Until they break. The problem lies when you start wanting to reuse lid jars.

While you certainly can reprocess jars, The lids are an entirely different story.

First, Yes, people do in fact reuse lids all the time. For the most part it’s a perfectly safe thing to do and you will likely have no problems given that the lid is in good condition with no bends and warping.

In fact it’s not a terrible idea to have these old lids saved up in a box somewhere in your kitchen for when you run out of new lids.

There is no shame is reusing. The problem comes from the question of is it worth it.

Consider this, You have a used lid, It looks perfectly fine and you don’t think it should have a problem sealing.

So you try it out and low and behold, It doesn’t pop. You have now wasted all that time trying to can that thing only to have to do it over again with a new lid.

What a huge time waster. So is it worth doing to save a few pennies? Yes, But is it worth risking the amount of time you could potentially lose? Yes in some circumstances i think it is.

It should also be noted that there are lids designed specifically to be reusable. These lids will often be of higher quality and durability, with better sealant around them.

They are less prone to failure unlike most 1 time use lids (Not that you would have a whole lot of problems reusing 1 time lids as I’ve said).

So, Can you reprocess jars that don’t seal? Yes, but, I guess it really comes down to personal preference. If you want to save money, invest in better lids to begin with, ones that are built to be reused.

Check out our article on the benefits of canning to see why you should start canning

How long does it take for jars to seal?

Now that we got that out of the way, Lot’s of people don’t realize how long it can take for a jar to seal. We all wait for the moment to hear that beautiful POP on all our jars, But how long do i have to wait around to hear it?

There is no clear set time as each jar tends to be it’s own beast. Every jar is going to have it’s own unique time frame to ‘pop’ and it also depends whats in it.

Sometimes a jar will pop immediately after you take it out of the bath, Sometimes it can take up to 2 hours! Sometimes you won’t even hear the pop, and a jar will silently seal.

That’s why it’s so important to check your lid after 2 hours to make absolutely sure it has sealed, even if you didn’t hear it. Here is an example of what the pop will sound like:

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So what other methods are there to check to see if there is a proper seal if not just for a pop?

How to know if canning jars are sealed?

Even though I said that in normal circumstances a seal should be had in 2 hours, That doesn’t mean you should check in 2 hours.

If you want to know if canning jars are sealed you should first wait for the jars to cool down before checking.

The reason for this, if the jar is still hot, testing the lid seal could in itself break the seal. Loosening it or jostling it prematurely could also cause a false seal.

After 6-12 hours depending on how long it took to cool down, The first test you should do is the lid press.

Each lid is designed in such a way that when you press it, it will make a clicking sound when not sealed. If you were ever a kid or around kids, You probably recognize what im talking about, from glass fruit juice jars.

Kids will drive you mad with those clickers. Well, same principle. If the jar is in fact sealed, there will be no click and the lid will have a suction on it preventing it from popping up.

So to recap:

Sealed: The lid wont cave inwards or move at all, there will be no clicking sound as there is a positive pressure pulling it in.

Unsealed: It will click, it will move, No good. You will need to reseal this jar.

Great! That’s the most obvious method. Another is spoon tapping. I’m not going to go into the science of pressure differentials and harmonics here, it really isn’t necessary to understand why and it works, just that it does.

Any who, The method is simple, Tap the lid with the butt end of a spoon (the handle, for you silly folks out there).

If there is a high pitch sound it means it’s sealed, if there is a slow low pitched sound, make sure there is no food touching the top, than do it again. if it continues, it’s a dud and will need to be reprocessed.

What to do if canning jars just don’t pop?

If you did the above to check if the jar was sealed and it just wasn’t, There are a few reasons this could happen.

The jar was in bad shape, Had a chip or a crack in the lip and air was able to get in. It could be the jar was overfilled and there wasn’t enough room to create the pressure necessary for the lid to seal.

You didn’t clean the jar well enough and there was a piece of foreign matter left in under the seal. And the list goes on, So always follow this checklist.

  • Inspect every jar for cracks or chips before you fill and sterilize them, check again after.
  • Make sure to follow the fill to line on the jar, and don’t go above it.
  • Make sure the jar lips are wiped sufficiently to remove any debris that might prevent a seal.
  • Check the lid placement, Lot’s of people rush tossing the lid on and often won’t be in proper alignment.
  • Don’t tighten the ring while the jar is cooling and sealing.
  • Make sure you follow all the temperature guidelines for what ever you happen to be canning.


How to clean Mason Jar Lids so they can be re-used properly

So if you’ve decided that you really want to re-use your lids, That’s fine. But you should be sure it’s done properly to avoid any unwanted issues! The last thing you want is to have to do all that work over again because of a dirty lid.

Another issue is smell, Yes, lids can absorb odors! Don’t cross contaminate your fresh tasty preserves with the over powering smell of onions or garlic!

  1. bring water to a rolling boil, than turn off the heating element. Allow the water to settle and place your jars lids to soak for 20 minutes
  2. remove them and gently wipe them down with a soft cloth, do not use paper towel
  3. if they still have a strong smell, Add them to a bowl with baking powder and water, The mix should be thick. Allow to sit for 1 hour
  4. Repeat if necessary

That should get rid of the smell, But what about the stains? Depending on what you last used it on and for how long it was in contact, There could be staining on the lids.

Normaly that’s not something you should care about as it doesn’t effect the ability to make a seal nor do they smell after you’ve went ahead with the above steps.

But, if your a perfectionist and really hate those nasty stains, you can soak them in distilled vinegar until you see the stains disappear.

How to tell if canning lids have been used?

If you’ve found an old box of canning lids under the sink or in the basement and your wondering if they are used, first ask yourself how long they’ve been down there.

Are they too old? How long can canning lids last?

The gaskets on most lids have a lifespan of about 5 years before they become unreliable. Now if you know they aren’t that old and want to find out if they’ve been used or not, let’s continue.

Telling if a lid has been used is relatively simple.

  • Is it still in the original box or packaging?
  • Is it bent or misshapen in any way?
  • Does the seal look cracked or dirty?
  • Is there any rust on the lid?
  • Does it generally look used

Aside from packaging, if you answered yes to any of these questions, the lids were probably used. And on the off chance they weren’t, they are probably still not worth using as they likely wont hold a seal.

Don’t forget to check out our other article on canning apple butter with out the use of sugar! Curious about other preservation techniques? Check out these:

How to store fresh Pasta

how to store fresh asparagus

How to store fresh basil

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