Anatomy of a Canning Jar

Some parts of a canning jar can be reused; others cannot. Know the difference!

Photo: Southern Foodways Alliance

If you’ve never preserved your garden abundance by canning, the system can be a little confusing. A friend of mine—one who’s never canned before—was asking about home preservation and I was reminded that although I grew up understanding how a canning jar works, many people just don’t.

The jars

The jars most commonly used for home preservation these days come from Ball and Kerr (both made by Jarden Corporation). They are glass and come in a variety of sizes, from small four-ounce containers to half-gallon sized. All of these jars are approved for home canning use except for the half-gallon size (I use the half-gallon size for storing dry goods). The small sizes are good for jams and jellies, especially those that you plan to give as gifts. Jars come in both a standard or wide mouth, referring to the size of the jar’s opening. Wide mouth jars are useful for preserving larger items like peach halves or for pickles that need to be placed in the jar by hand.

Glass canning jars can be washed and reused from year to year. I’ve collected a good quantity of jars over the years by keeping my eyes open at garage sales. If you’re looking for second-hand jars, just remember that jars with chips around the rim should not be used for preservation, as the chip can compromise the seal.

The Lids

Canning lids are typically metal, a flat disk with a ring of rubber around the perimeter. This rubber ring allows the food to remain sealed inside the jars after processing. Lids come in both standard and wide mouth sizes to correspond with the jars. Unfortunately, these metal lids are not BPA-free. Jarden rolled out BPA-free lids in early 2013.

Metal canning lids cannot be reused for home preservation. Once a lid has been used, the seal becomes compressed and it will be more difficult to get the necessary airtight seal. (That seal is critical to creating a product that is safe and free of botulism.) You must purchase new lids for each new canning project. Lids are sold in sets of twelve and can be purchased separately from jars and rings.

An alternative to metal canning lids are the plastic lids made by Tattler. These come in two pieces — a plastic disk and a rubber ring. Tattler canning jars are BPA-free and can be reused from year to year.

The Rings

Metal rings (also called bands) also come in both standard and wide mouth sizes. These are screwed over the lid to hold the lid in place during the canning process. Once your jars have cooled and the lid is sealed, rings are removed and can be used to process another batch of jars. This means that you don’t need as many rings as you have jars. Rings can be reused indefinitely, but they do tend to rust over time.

Photo: Weck

Weck Jars

The jars from Weck are in a category of their own. Both the jars and lids are made from glass, and thus reusable. The sealing ring is rubber and also reusable. The sealing process with a Weck jar requires a couple of metal clips that hold the rubber ring and glass lid in place during processing.

Weck is a European company and while the jars are available on their website, you won’t find them readily available in the USA.

This post is part of Simple Lives Thursday on GNOWFLINS.

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  • This was interesting. I’m a novice but realize I have to learn. Why, oh why, is there BPA on the lids?

    • Kris Bordessa ,

      Why, indeed! I suppose because nobody thought about the health ramifications when BPA first started being used. And now it’s in everything.

  • Sheryl ,

    Impressive – you really know your jars! I don’t do any canning, but have always admired the styles of these jars, nonetheless.

    • Kris Bordessa ,

      Sheryl, I love the way the jars look, too. But stick around. You might become a convert to canning!

  • Yelena ,

    I remember my mom used Weck-style jars back in the “old country”. Putting the metal clips on the lids seemed difficult to me even when I tried that with cold jars. But the nice thing was that the lids and all were reusable year after year. We did have to buy the rubber rings once in a while to replace the dried out or damaged ones. Here in the States I use Ball jars – good results and very easy to use although I feel bad about throwing away the metal lids.

  • Kris Bordessa ,

    I do use the “spent” lids to store dry food in Mason jars, so I rarely throw them away. But I wish I could reuse them for processing!

  • I’ve only attempted things like jams and jellies, and it was a boatload of work, especially the year I decided homemade orange marmalade was a good gift idea. Scraping the peels took forever.

  • Yep, it’s almost that time of year again. I canned for the first time last year and looking forward to this year!

  • How I wish I would have listened more when my mom was canning. This post is helping educate me–if only I’d offered to take her canning jars when she was giving them away!

    • Kris Bordessa ,

      Start letting people know. In all my years of canning, I’ve only purchased a couple of cases brand new, thanks to neighbors and friends who passed theirs along, or told someone else that I’d take their jars!

  • Growing up on a farm, my mom canned everything. I’m mostly familiar with Ball jars, but those Weck jars are so pretty.

    • Kris Bordessa ,

      I love the Ball jars, too, though. They’re so old fashioned and comfortable!

  • I love those Weck jars too, but (like you) I can’t justify buying them when there are truly dozens of Ball jars all around my house. Gotta be frugal around these parts!

  • I think I’ve reused metal lids before, for homemade yogurt. Oops! I have yet to really can though we have a million of these jars and we use them for leftovers and freezing berries and freezer jam, etc.

  • Polly Loy ,

    Anyone planning to do home canning should use only those recipes thoroughly tested. Extension is the mmost reliable source of all things canning. University of Georgia Extension is the national clearing house for research and resources. Check out their website at Homefoodpreservation.com – you will be redirected to a uga site. they have recipes, instructions, videos, FAQs and more.

    Don’t rely on information published before 1988 and don’t use recipes from cook books – except those published by major canning equipment companies – like Ball, Kerr, and Presto.

  • coco_cana ,

    Just found your site today. I’ll be following you for sure!  Thanks for the great info. 

  • Connie ,

    Can you reuse lids for things that you aren’t canning? Last year I made pickled peppers but we ate them within the month so we weren’t storing them unrefrigerated. I also make elderberry syrup frequently and reuse jars. I’m new to all this so any advice would be helpful. Canning is still a ways down the road but something I’d eventually like to do. 

    • Kris Bordessa ,

      Oh, you can use the flat lids for storing dry goods and as someone else mentioned, with one of those food saver things. You just can count on them for a safe seal when you’re *canning foods for long term, shelf stable storage.

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