This is great! I found Weck jars at a garden store and asked about them, and I couldn't figure out why anyone would buy a jar that's so much more expensive!
My main concern with Weck is safety. I can tell I've canned sucessfully, and there's a seal, by the metal lids popping down. I only can acidic things, but I wait for the popping.
I often have a couple in a batch that don't seal, and I put those jars in the fridge and use them before the rest, which go in the pantry.
I was taught canning by master canners, who are trained here by the University of Minnesota Extension Service, now not doing nearly as much as it once did. The whole method depends
on the metal lids that you can see and hear popping. Every canning guide I've ever read was published by a canning jar company, like "The Blue Ball guide".
I remember canning with my neighbor, as a young housewife in 2004, and we just followed all the instructions in that manual, scrupulously.
When I saw the Weck jars, I was interested in them, for not having reactive material in the lids, and asked the store lady who was promoting them,
"But, how can you tell they're sealed?" She didn't know. I figured they couldn't really be safe.
So, I propose that a main reason Americans don't use Weck jars is that our canning methods and education come from American canning jar companies.
-I do stack my wide mouth, and sometimes regular mason jars, but it is precarious! I have canned goods stored up high, and they are always threatening to fall.
-And we break them all the time. My sons are my main dish-doers. And we also use them as our drinking glasses. It happens.
-So I would like more stackable jars, and also don't like the reactive metal coated in who-knows-what on the lids of mine, though I do get more than a few uses out of them.
(reusing metal lids also not officially recommended)
-And, there are foods that come in l canning jars. Classico sauces, some jams--a basically free source of the metal-lid canning jar. I don't get this food much anymore, but I sure used to.
-Plus, I have a lifetime supply of jars in the basement from my Grandma, and all kids of other people who don't can themselves, so they give their jars to their canning friend or neighbor.
So, I'm excited to hear about Weck. I'd love to switch if possible for all the above reasons, if I can know the food I store will be safe.