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

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Are you having trouble getting the lid to seal when vacuum-packing a Mason jar?

It’s 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.

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Wide-mouth attachment as seen upside-down

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

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See the bumpy rim on this jar?

TEN TIPS FOR GETTING LIDS TO SEAL ON A MASON JAR WHEN VACUUM-PACKING:

  1. Is the flat lid bent? (You can reuse these lids many, many times so this will occasionally happen.)
  2. Does the rim of the jar have a crack or chip?
  3. Is there a piece of food between the lid and the edge of the jar preventing a clean seal?
  4. Is the rubber gasket on the attachment dirty? Wash in soapy water.
  5. 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.
  6. Is your jar a mutant like the one I described above? Use it for something else that doesn’t need to be vacuum-packed.
  7. Foreign particles may be blocking the hole in the attachment at the top where 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.
  8. If you are using a hand-held sealer, you may not be pressing firmly enough, or 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.
  9. 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.
  10. 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.

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-packing process is not a substitute for heat canning. Perishable foods must be kept in the refrigerator even when vacuum-packed.

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{ 20 comments… read them below or add one }

Vicki W. April 5, 2013 at 3:23 pm

Thank you, Paula, for this post. I am definitely passing it on to friends who are vacuum sealing mason jars. I agree with you that it is much easier to seal the wide mouth jars. If buying new, that’s what I go with. However, I have a lot of the regular mouth sizes and as I store dry goods in my pantry, I do use them. The double lid trick is what usually works for me. If I had not found out about that trick, I imagine I would have been one frustrated lady, lol. Just yesterday I showed a young man (whose family is into emergency preparedness) how to vacuum seal with a Ziplock hand pump and a widemouth Foodsaver jar adapter and jar. It took several tries (even with me guiding) to get it. But once he got it – he got it! So hopefully everyone will not give up. And I really think your videos are REALLY helpful. If they follow your suggestions, I’m sure they will have success.

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Vicki W. April 6, 2013 at 4:31 am

I was just talking with a friend and suggested something I would like to add. I always use a canning funnel when I add my lettuce or pantry goods to the jars. That way the jar rim stays nice and dry when packing lettuce, or powdery things don’t get on the rim to interfere with the sealing process. The funnel only costs about $1.50 and lasts forever.

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Paula April 6, 2013 at 10:25 am

Thanks for the suggestion about the funnel. Great idea! Don’t take up storage space either.

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Rachel April 6, 2013 at 12:29 pm

I wipe the jar rim with a damp paper towel before applying the lid. It always works for me. Rare time it does not, I use the double lid method.

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Paula April 6, 2013 at 10:12 pm

Good habit, Rachel.

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Betty April 6, 2013 at 1:02 pm

I’ve never tried the double lid method- that will come in handy! :)

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Karen M April 6, 2013 at 1:16 pm

I love this and am on my second batch of lettuce (Romaine and Iceberg) BUT I also use it for cucumbers and another jar for green peppers. My husband and I are retired and with just the two of use, we don’t use up some of the produce as a family would. I am going to use a smaller jar for my ginger and for garlic. Before I know it – I might have a whole refrigerator full of jars! Thanks I love this idea.

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Paula April 6, 2013 at 10:11 pm

Hi Karen,
Thanks for writing. Both my refrigerator and pantry are full of Mason jars which also means my dishwasher and cabinets are often full of them too.

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TimAyn Stafford April 9, 2013 at 1:16 pm

Thank you for sharing this awesome technique! My foodsaver does not have a attachment port, would the same result occur if I used a food sealer bag?

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Paula April 10, 2013 at 6:21 am

TimAyn, I do not use the bags for lettuce because the leaves would be crushed. The jars protect the lettuce.

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Paula Erisman April 16, 2013 at 8:07 am

I have not been successful printing any of you instructions from the print/pdf. Not sure if it is my printer for sure. Thought I would let you know. I end up highlighting and printing that way. Your method for making Greek Yogurt is the best. Thanks so much for simplifying it. I have done it twice now and have told several friends.

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Paula April 17, 2013 at 7:17 am

Hi Paula,
Sorry you aren’t having good luck with the print button. I just tried it myself and it worked fine so not sure what to tell you. But if highlighting and printing works for you, then all is well, although not as convenient. :-(

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Marla Riedling April 27, 2013 at 1:27 pm

I would like to add one little thing that can also make a difference in the longevity of ANY fruit or vegetable: use a porcelain knife!!!!
You can get them at any Harbor Freight store and I just noticed they have them at Walmart now too. The difference between using steel versus porcelain is incredible! No more brown edges. Period. Try it and you will be sold! :)

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Paula April 27, 2013 at 2:36 pm

Hi Marla,
Thanks for writing. I did a little experiment with knives and vacuum-packing in regards to chopped romaine lettuce. You might find it interesting. You can read about it here.

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Toni November 29, 2013 at 6:54 pm

How do you unseal the lid without bending it?

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Paula November 29, 2013 at 9:49 pm

Very carefully. I use a pop top can opener.

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lynne March 12, 2014 at 6:30 pm

Hi I made two jar salads the other nite and just put tops on with my hand Should no be vacuuming first? Seems like a large expense?

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Paula March 13, 2014 at 7:57 am

Hi Lynne,
I’m not exactly sure what you mean by “jar salads”. If you mean you put lettuce and other veggies in a jar together, it is best NOT to vacuum-pack them. They won’t stay fresh long but since you only made two jars, I guess it won’t take you long to eat them. See this post. On the other hand, if you put only chopped lettuce in the jars and you want them to last a week or longer, they will stay much fresher when vacuum-packed. It doesn’t have to cost a lot of money. See this post. You can also do it cheaply with a hand-held vaccuum-pack machine. See this post.

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Erica July 6, 2014 at 7:45 pm

Way late to the party here, but I found you on a google search because I couldn’t get my jars to seal. Was making me crazy! I’m not doing this for lettuce, but for a conserve I’m going to freeze and I wanted to remove the air before the freezer. The 2nd lid worked like a charm.

Thank you for posting this!!!

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maj October 31, 2014 at 12:03 am

I’m not from the US, so the ziploc vacuum isn’t really an inexpensive option. Wondering if this would work? Aka, how big is the hole on the top of the foodsaver suction device?

http://www.ebay.com/itm/Manual-Air-Pump-Seal-For-Compressed-Saving-Saver-Bag-Storage-Vacuum-Space-Green-/390569716853

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