Recently, after panting after them for years, I finally broke down and ordered a dozen Weck jars*. For those of you not in the know, they are a brand of canning jar that is produced in Germany and is quite popular across Europe. Instead of using a disposable lid with the sealing compound embedded in it (like our familiar Ball and Kerr jars), these jars depend on a rubber ring for their sealing power.
They are much like the bailing wire canning jars that were once quite popular across this country (I wrote about canning in those jars here, if you care to give a gander). One of their primary benefits is the fact that because the lid is made from glass, the only thing that’s in contact with your food is glass (just like the Tattler reusable lids, there’s no BPA-imbued surface to worry about when you use these suckers). They also feel a bit less wasteful than the Ball/Kerr jars, because the only piece you end up throwing away is the rubber ring, not an entire lid. The primary downside of Weck jars is that they are expensive. I have hopes that if enough people start buying them, they’ll become more accessible and affordable here.
The Weck jars are made up of four components. The first is the rubber ring, which is the analog to the sealing compound in American lids. And just like our lids, these rings need to be submerged in boiling water for a few minutes before use in order to soften up. Keep them in the hot water until the moment you’re ready to use them to maximize their sealing abilities. These rings should also be given a once over before use, to ensure that they don’t have any cracks or tears. Another way these rings are like conventional lids is that they can only be used once.
Next comes the flat, glass lid. Prior to use, make sure to give them a careful inspection, to ensure that the lid is free from chips, particularly on the edge that comes in contact with the rubber ring. Even the smallest chip can prevent a quality seal. Keep in mind that if you’re planning on processing something in these jars that will be in the boiling water bath canner for less than ten minutes, these lids need to be sterilized along with your jars.
I have found that the best way to assemble these jars is to caress the rubber ring onto the lid and then place the lid on the jar. Before you settle it into place, make sure to wipe those rims. It’s just good canning practice.
Now come the clips. All Weck jars come with two stainless steel clips. They do the work that our screw-on bands typically perform, holding the lid in place so that air can escape during processing and cooling, but no air or liquid can get in. I believe the best way to attach a clip is to hook it over the lid and then firmly (but carefully) push down. There should be a satisfying click when the clip is in place and there should be no wiggle or movement. I have found that it often requires just a hair more pressure than feels appropriate. Take it slowly and make sure to hold onto the jar (wrap a towel or pot holder around it so you don’t burn yourself) so that you don’t slosh the product on to your counter.
Once you have the clips in place, quickly check the status of the ring. It should still be flat and even between the top of the jar and the bottom of the lid. On one occasion, I have had the ring wrinkle up while I was finessing the clips onto the jars. Had I not caught it before the jar went into the canner, I could have compromised my potential seal.
Now that your jars are filled and the rubber rings, lids and clips are in place, it’s time to process. This step is just like all other boiling water bath canning. The only caution I have to offer here is to take care with your jar lifter placement when working with Weck jars. I once nearly tipping several jars over while maneuvering in and out of the pot because my lifter caught on the clips. They hold tightly enough that you shouldn’t be able to dislodge one with the lifter, but it is something to be aware of.
Once the jars are finished processing, let them cool fully. Once they are totally cool to the touch, you can remove the clips and check your seals. There are two easy ways to ensure you’ve got a good seal. The first is to grab onto the jar holding onto just the lid and lift the jar just a bit (I will never be a hand model). If it holds, it’s good.
The other way to check the seals is to take a look at the tab. It should be pointing down, like it’s sticking its tongue out at you. Also note that Weck jars should be stored with the clips off when it’s on your pantry shelf. This is for the same reason that we store Ball and Kerr jars without their rings. If something happens to grow inside the jar, the off-gassing will break the seal and you’ll know right away that the product is compromised.
When it comes time to open a Weck jar, it’s incredibly easy. Just grab hold of the tab and gently pull it, until you hear air rushing in and the seal breaks. Do this slowly, so that you don’t run the risk of popping the lid off the jar with too much vigor. While the jar lives in the fridge, you can use the clips to hold the lid in place, or you can invest in some of the snap-on plastic lids that Weck makes as well.
For information on how to pressure can in Weck jars, read this post!