Weck jars are just soooo very pretty! I had to add them here. I don’t usually write about anything not tested and approved by the NCHFP, and I believed that Weck jars had never been tested.
I have new information. It was pointed out to me that Weck canning lids actually HAVE been tested. There was a study done under the guidance of the University of Georgia in 2014.
This Page Includes:
Are Weck Jars Tested?
This article I just linked is in-depth and explains all the specifics of the testing done. They studied traditional 2 part metal lids, plastic reusable lids, and glass lids. It is a very long read. However, what stood out to me is this phrase in the introduction of the study…
“Our results demonstrated that all three lid types had acceptable sealing performance and vacuum levels with all the treatments.”
The study does go on to state that they still recommend for best results the traditional (in the US) 2-piece metal lids. But they don’t say that glass or plastic reusable lids are dangerous in any way. They are acceptable.
I have a link here I’ll share with you so you can get all the information and details of the study…
Apparently, there is more research that needs to be done on the seal in longer-term storage.
I don’t claim that they are now endorsed! …but to me, that is encouraging.
So…I leave it to you, my wise reader with a good head on your shoulders. You decide if you are comfortable with using these jars.
As for me, I probably will not use these in a pressure canner as Pia does in the article below. The traditional lids are so convenient and Weck canning jar lids are expensive for the amount of canning I do.
But I am encouraged by the study done. And I really, really, really want to use them to create some gift jam jars, because like I said above…Weck jars are just soooo very pretty!
This post contains affiliate links.
This guest article below has instructions and tips on how to use Weck jars, some of which I didn’t know! With that, let me introduce Pia Sonne. Pia lives in Denmark where these jars are much more common. US standard Ball jars are very hard to find. She has some recommendations regarding how to safely use these jars.
Why I Can with Weck Jars
Guest post by Pia Sonne
Weck jars are gaining in popularity. If you are planning to use them for pressure canning, there are some things you should be aware of.
I quickly realized that none of these is available where I live. A quick search on Amazon resulted in a major sticker shock.
Thankfully, my awesome community of homesteaders came to my rescue. They gathered their pennies and refurbished a 1940s pressure canner for me. It even made it through customs with their help.
I was able to get the Ball Complete Book of Home Preservation and the Norpro Canning Kit from Amazon. The only thing left was the jars.
Ball jars are impossible to track down here. If you find a similar Mason jar, it has a very different top.
I set out to do a little research, that turned into a lot of research, which I will share with you now so you don’t have to go through it.
I ultimately decided that my best option would be Weck jars.
They are readily available but quite pricey. We took our time growing our collection at birthdays and with some savings. Finally, we were all set for our first canning session.
Our First Canning Experience
We opted to can potatoes because we love potatoes. I’m allergic to raw potatoes, however, so it would be nice to have some on hand.
It was a nightmare, and we made a mess.
We could hardly fit any jars into the canner. I was desperately trying to figure out what canning time to go with.
The funnel from the kit didn’t fit the jars at all. Worse yet, the jar lifter was no good. We almost broke all the jars because we dropped one on top of the others.
We had no use for the rest of the dodads in the kit, except the bubble popper/measurer.
Needless to say, it took a while before we decided to attempt any canning again. Although we did end up with four jars of delicious canned potatoes.
We had wasted money on tools we didn’t need, which was a bummer. We also had to buy new tools.
I wish someone would have told me all this before I got into canning, and that’s why I’m sharing my experience with you. Let’s take a quick look at the pros and cons of canning with Weck jars before we dive deeper into some of them.
Pros for Canning with Weck Jars
- Zero-waste: The jar and lid are glass, the ring consists of compostable rubber, and the clamps are metal.
- No rust on rings or risk of turning the rings too tight.
- Beautiful: There’s no coming around it. Weck jars are just plain beautiful.
- Available in places where Ball jars aren’t. To some of us, this is a deciding factor.
- You need fewer tools if you only can with Weck jars.
Cons for Canning with Weck Jars
- Not USDA approved. This could be a deciding factor for you.
- The jars are expensive.
- You can generally fit fewer in a canner than with Ball jars.
- You need different tools than for Ball jars.
- You don’t get that awesome PING sound when the jar seals.
Weck Jars are Not USDA Approved
We all want to be safe when we do home canning. None of us wants to poison our families. We know all too well that botulism is not something we can see, smell, or even taste.
I recommend following USDA processing guidelines and recipes for canning with Weck jars.
So why are we even discussing using canning jars that are not approved by the USDA?
To my knowledge, the USDA has never tested Weck jars. As a result, Weck jars are “not recommended” for home canning.
(Sharon’s note…. in case you are skimming and missed it, check the top of this page for new information on a study that has been done.)
This is very different than being deemed dangerous by the USDA.
This is what it means:
Since they haven’t run any tests on the jars, they have no official stand on them. That’s why they don’t recommend them for home canning.
Europeans have used these jars for home canning for decades. Yet, it’s up to you to decide if you are comfortable using Weck jars for home canning.
If you opt to use them, you still want to follow tested canning recipes, times, and procedures as recommended by the USDA.
The Tools You Need for Canning with Weck Jars
One of the benefits of canning with Weck jars is that you don’t need very many tools.
It can also be a drawback if you are already an avid home canner. You do need to invest in the first two if you don’t want to make a mess as we did.
Besides the jars and your pressure canner, you need:
The Difference Between Weck & Ball Jars
Ball jars come in standard sizes from quarter pints to gallon jars. You can choose between wide-mouth or regular mouth, and that’s pretty much it. When it comes to Weck jars, you have a lot more choices to make.
Weck Jar Shapes
Weck jars come in different shapes:
- Sturz (which is the one I use the most and would recommend)
The Sturz, Mini-Sturz, and Zylinder jars are all straight-sided. This makes them the best-suited jars for canning.
Mouth & Lid Sizes
Besides the shape of the jars, you have to pay attention to the lid size.
Lid sizes are listed as RR + a number, i.e. RR40 or RR100. Jars of the same shape can use very different lids.
To make your canning easier, I recommend sticking to one lid size. We have several different types of jars, but they are all RR100.
In Europe, Weck jars are advertised with their actual capacity in ml. If you find ml confusing, you can always ask Google to convert it for you.
Weck jars don’t come in your standard quarter-pint to gallon capacity sizes. The capacity is often an odd amount, such as 370 ml.
In the States, Weck jars are furthermore often advertised with a rounded amount. This means the 370 ml jar would be advertised as 350 ml (they always round down).
It’s important to take note of the actual capacity of a jar. You need this information when you calculate how many jars you need for a recipe. It’s also very important when you decide on the processing time.
How Many Jars Will Fit in Your Canner?
There is one final point to be aware of when it comes to the size difference between Ball and Weck jars.
You will generally be able to fit fewer Weck jars in your pressure canner than Ball jars. That’s because the Weck jars taper out at the top making them wider at the top than the bottom.
Look up the measurements of the particular jars you want to use and calculate how many will fit in your canner. Make sure you get the top measurements and not the bottom circumference.
Choosing the Processing Time
The capacity of the jars rarely fit exactly with the measurements in tested recipes. This means you always want to use the next time up.
Processing time vs. capacity matters.
You never want to use a processing time tested on a lower capacity jar.
Choosing the Headspace
You also need to pay attention to your headspace. The shape of the lid means it comes down about ¼ inch into the jar. For this reason, you never want your headspace to be less than ½ inch.
As a rule of thumb, you should add ¼ inch to the headspace your canning recipe calls for.
How to Check for a Proper Seal
One of the downsides to using Weck jars is that you don’t get that wonderful PING! sound every time a jar seals.
That said, it’s very easy to tell if a jar has sealed.
When a jar has correctly sealed, the flap on the rubber gasket will turn visibly downwards.
After you have waited the recommended 24 hours, you remove the metal clamps. You should now be able to lift the jar by the lid.
A Zero Waste Option
The Weck jar is a great zero waste option for home canning.
Every element of the canning jar is recyclable. You also don’t have to deal with rust since the clamps are made from stainless steel.
In Europe, the producer has no qualms about people reusing the rubber gasket several times. As long as the gasket appears solid, with no big cracks, it should be safe to reuse. If, for some reason, the gasket is not okay to use, the jar simply won’t seal.
The official stance is a little different in the States, where it’s recommended to only use the gasket once.
Again, it’s up to your judgement if you will reuse gaskets. Once a gasket no longer works, you can throw it in the compost and it will decompose.
Here are some of the key take-aways:
- Canning with Weck jars does require a few special tools. You have to pay attention to the capacity of your jars and their lid sizes.
- You always want to use the next processing time up and add a ¼ inch to the called-for headspace.
The jars are beautiful, yet expensive. If you don’t have access to Ball jars where you live, Weck jars are a good investment. However, you have to be comfortable canning with jars that have not been tested by the USDA yet.
Pia Sonne is a homesteader at heart. She lives in Denmark and blogs at Busy Hands Quiet Hearts, where she helps you get your financial house in order. You can find more of her homestead-related writings here.
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Page last updated: 11/5/2021