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Demystifying Weck Jars

Weck jars -

Over on my podcast this week, I answered a listener question about Weck® jars.

Now, I do not normally cover things that are not approved by the USDA guidelines for canning, but…

In this blog post I explain:

  • What it it means to NOT be USDA approved for canning
  • The 4 components of a Weck jar
  • A brief overview of how Weck jars work
  • The pros and cons of Weck jars vs. our standard jars like Ball® or Kerr®

If you would rather LISTEN to this info, head over to this week’s podcast episode.

To be honest, there is always a little more information in the 20-30 minute podcasts than I can fit in a single blog post. So to get the fine details, you can listen or read the transcript on the podcast page. But this post is a summary of all that I discussed in that episode.

What Are Weck® Jars?

Weck is simply a brand name of a line of canning jars that are made in Germany.  They look very different from the type of jars we’re used to here in the United States.

They come in a variety of unusual shapes and sizes and they use a different lid (gasket with clips) than our standard two-piece lid with a screw-top ring.

All About Weck Canning Jars -

Not USDA Approved:

Now, right off the bat – I need to tell you that Weck jars are not USDA approved for canning in the United States.

But let me explain what that means because this is very different from them being called out as “dangerous”.

Here’s the deal…

As canners, we usually follow United States Department of Agriculture (USDA) guidelines when canning. These are the recommended guides and procedures (including processing times) that we follow to be safe.

There are currently no USDA approved procedures for using these jars because there has never been a study funded and performed by the USDA or extension service on these jars.

You see, for something to be called out in the USDA canning guidelines, it has to be studied and the research pulled into the procedures.

So, it’s not that they have been deemed dangerous, necessarily. It’s that they have not been tested.

For now, the official stance by the USDA is that they are “not recommended”.

It is important for you to understand this because I do not normally write about things that do not clearly fall into the USDA guidelines.

But to answer a listener question, I am explaining how they work.

It’s up to YOU to decide if you want to “assume the risk” as they say and use Weck jars when they do not have the official stamp of approval by the USDA.

The purpose of this post is to just give you a general overview of how these jars work and why they are so loved by many canners.

Their Popularity:

They may not be USDA approved, but Weck jars are extremely popular in Europe. In fact, they are the equivalent in popularity to our standard mason jar and they have been used for decades there.

You might be wondering if I ever use them myself — Well…yes, I do.

I use Weck jars in a limited way for water-bath canned products like jams and pickles. I don’t use them too much beyond that because they are a lot more expensive than our regular canning jars here in the US.

When I am not using my jars for canning, I use them to store things. I love the look of these jars and want to enjoy them by keeping them in use as much as I can.

How to Use Weck Canning Jars -

The 4 Basic Parts to These Jars:

Weck jars have four distinct parts:

  1. Glass Container: They come in really unusual shapes and sizes. And when I say unusual, I mean beautiful!
  2. Glass Lid: Instead of the metal lid we are used to, these jars have glass lids.
  3. Gasket: The rubber gasket has essentially the same purpose as the rubber gasket that is embedded into the metal lid of a typical mason jar. It is what will help you create the seal.
  4. Clips: Stainless steel clips snap down onto the lid and hold the lid in place during processing.

How Weck Jars Work

Without going into the fine details of canning here – let me give you a brief overview of how these jars work so you can understand how these gaskets and clips function.

  • First, you heat the jars and lids in hot water and soak the rubber rings in hot water to soften them.
  • If you are processing the jars for less than 10 minutes, you would also need to sterilize the Weck jars just as you would standard mason jars.
  • After your jars are filled with your preserves, you wipe the rims and place a rubber gasket onto the glass lid. Then you set the lid (with gasket) on top of your jar.
  • At this point, you add the metal clips to hold that lid in place during processing.
  • It takes a little time to get used to using those metal clips because they snap down really hard and you feel like you’re going to break the jar. But after a few uses, you will get the hang of it.
  • The process time is based on the jar size – since the jars are in metric, there may be some math involved as you have to determine the length of process time.
  • After processing, you let the jars sit and cool just like you would any other jar. As they cool, they create the vacuum seal. 
  • Weck jars are used for both water bath canning and pressure canning.
  • Once they’re cool, it’s important to remove the clips. The clips are only there to hold the lid in place during processing.

This last step is done for the same reason that we do not store our canned goods with the screw rings on.

Wait…You didn’t know that?

No problem. Just Read:  Why Remove the Rings to learn why.

Is It Sealed?

Now, you may have noticed that you can’t push on the glass lid to see if the jar is sealed (like we do with our standard metal lids).

So…How do you know if it’s sealed after processing?

Well, it is pretty simple really…

The gasket has a little handle or tongue that sticks out from the jar. When sealed, that tongue points downward. So you can quickly see visually if the jar is sealed.

You can also pick the jar up by the lid (without the clips on, of course) and the lid should hold the weight of the jar without popping off.

How to use Weck Canning Jars -

3 Reasons People Love Weck Jars

1: The shapes: The number one reason people love Weck jars is because they come in beautiful shapes. 

2: All Glass: Since they are made entirely of glass, there is no plastic in contact with the food. In our regular canning jars there is a metal lid that has a plastic coating. And although most of those coatings are BPA free these days, they do still have chemicals in them. So even being BPA free does not mean chemical free. And a lot of people go to the Weck jars because they want to be completely chemical free while canning.

3: Reusable: Just like our standard mason jars, you can use them over and over again. The only part not reusable is the rubber ring. 

3 Drawbacks to Weck Jars

Now there are some downsides to Weck jars.

1: Expense: The biggest downside is that they’re very expensive. They’re much more expensive than our standard jars and part of the reason for that is because they’re imported from Europe.

2: Clips After Opening: Another downside is that once you open your preserves, the lid will just sit on top. This means that if you want to store the opened jar in the refrigerator, you have to use those clips again to hold the lid in place. 

However, there is a way around this.

You can buy plastic lids (also made by Weck) that snap on top of the jars. However, if the whole reason that you’re using Weck jars is because you’re trying to avoid plastic then this alternative won’t really work for you

3: Not USDA Approved: Finally, the last drawback of using Weck jars is one I mentioned at the beginning of the post — they are not USDA approved yet. 

There are a few more tips and tricks to using Weck jars, but they will have to come in another post.

So Tell me…

I hope this helped demystify Weck jars a bit for you!

Have you ever used Weck jars or do you plan to?

Tell me in the comments below!

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About the Author:

Theresa Loe is the founder of Living Homegrown® and the Canning Academy®. For 9 years, Theresa was the Co-Executive Producer & Canning Expert on the national PBS gardening series, Growing A Greener World®. Theresa homesteads on just 1/10th of an acre in Los Angeles with her husband, two sons and several disorderly but totally adorable chickens. Learn more about Living Homegrown here and about the Canning Academy here.