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Secrets of a Vacuum-Sealer: 10 Tips for Getting Lids to Seal on a Mason Jar

Are you having trouble getting the flat lids to seal on a Mason jar? Here are ten tips to consider.


It was a classic case of seeing things differently after you experience something yourself.

Over the last 3 years of blogging about salad in a jar (a method of preserving chopped lettuce in a vacuum-packed glass jar), I’ve had the occasional reader ask me why they couldn’t get their jars to seal.

I would gently repeat the original instructions and most would write back saying something was upside down, backward, inside-out, topsy-turvy, or whatever. And they finally got it to work.

Then it happened to me. I have one Mason quart jar in my cabinet that will not seal no matter what I do. NOW, I feel your pain, with apologies to all of you who have ever had difficulties.

wide-mouth attachment for vacuum-packing Mason jars

In this case, I think it is my jar although that may not be the case for you.

Why my jar wouldn’t seal

Regarding the wide-mouth attachment seen above, the blue rubber must form a seal around the ridge at the bottom of the top of the jar (see picture below). If there are any bumps or other irregularities, it may be unable to form that seal.

If you look carefully at the jar in the picture, you can see that the lowest ridge has some ripples. This is completely unnoticeable to the casual observer but I can feel it with my fingers. Looks like this jar will receive a new job description that doesn’t include storing lettuce.

Ten tips for getting lids to seal on a Mason jar when vacuum-sealing


Is the flat lid bent?

(You can reuse these lids many, many times so this will occasionally happen.)


Does the rim of the jar have a crack or chip?


Is there a piece of food between the lid and the edge of the jar preventing a clean seal?


Is the rubber gasket on the attachment dirty?

Wash in soapy water.


What brand of jars are you using?

Do they match up to the wide-mouth attachment? The FoodSaver website recommends Ball and Kerr brand jars. However, these are not the only ones that work. One person did some research and found that out of 12 brands she tried, 10 worked and 2 did not. Trial and error may be the order of the day on this one.


Is your jar a mutant like the one I described above?

Use it for something else that doesn’t need to be vacuum-packed.


Foreign particles may be blocking the hole in the attachment.

Check the top of the attachment where the air is sucked out of the jar. If you are packing something powdery, try cutting a piece of paper the diameter of the jar and laying it on top of the contents to prevent the small particles (e.g. powdered sugar or flour) from entering the attachment.


If you are using a hand-held sealer, you may not be pressing firmly enough.

Are you pressing at the right angle, or directly over the center to create a seal between your sealer and the top of the attachment. Sometimes, just applying more pressure to the white FoodSaver lid attachment while you are sealing will cause the jar to seal.

This tip actually solves the problem for me 95% of the time.


If you are using a full-size FoodSaver machine with a port, your hose may not be attached securely and completely.

Make sure it is inserted as far as it will go into the machine. Also, make sure the hose to the attachment is inserted securely.


No matter what method you are using, are you operating the machine long enough to pull out all the air?  

You should hear a difference in the sound of the motor as it slows slightly. If you are vacuum-packing with a hand pump, be sure you have pumped it several times and then do it one more time.

A tip that might help

FoodSaver suggests you try using two flat lids, one on top of the other if you are having difficulty getting a seal. Of course, you will remove the second lid when you are done as it is just laying on top.

I have found this tip most helpful when sealing regular-mouth jars (as opposed to wide-mouth jars).

For some reason, the smaller opening seems harder to seal, which is why I only buy wide-mouth jars if I’m purchasing new jars. Besides that, wide-mouth jars are easier to get the food in and out of and easier to clean.

If you are still having trouble or you have another suggestion based on your own experience, please leave a comment.

p.s. Just a reminder that the vacuum-sealing process is not a substitute for heat canning. Perishable foods must be kept in the refrigerator even when vacuum-packed.

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ivy d.

Saturday 4th of July 2020

i believe the problem is as mentioned above. it is the jar that is defective or not even so the sealer does not work. everytime i change the jar, seals every time.


Sunday 5th of July 2020

I couldn't agree more.

penelope smith

Monday 15th of June 2020

I thought that the type of jars you are using would make such a huge difference when it comes to sealing them. I wonder if industrial sealing systems can do multiple sized cans and jars. It seems like that would be a lot easier if you are doing something on a massive scale. I know that I wouldn't want to worry about having to change our parts.


Thursday 30th of April 2020

I can not thank you enough!!! 45 minutes of fighting, just about ready to throw my lid sealer in the garbage, and a last ditch effort lead me to your post. A dozen 12 ounce jars of home made turkey stock later...The 2nd lid worked perfectly! THANK YOU!


Friday 1st of May 2020



Monday 23rd of March 2020

I have a 5060 and it wouldn't seal a regular mason jar. THANK YOU for providing a solution by adding the second lid. This is a design flaw that Foodsaver knows about and should have corrected long ago. The 5060 is an excellent machine so I couldn't understand the failure. Thanks again!!


Monday 23rd of March 2020

You're welcome! ?


Saturday 21st of March 2020

Unable to seal my Ball mason jars. I've attached the the accessory hose correctly and feel it click in place. The accessory is attached properly and I've even used teo lids. When I operate my sealer though I realized there is absolutely no suction going on thru the accessory tube. What could be wrong?



Saturday 21st of March 2020

I figured it out. I have the FM2000 and I had already cleaned the gaskets to no avail. I hooked everything back up and started vacuum sealing the jar but this time I pushed down slightly on the the lid of the FoodSaver. Boom, all good. I probably need new gaskets but that added pressure got me thru todays project.