A while back, I mentioned that I kept finding shattered Ball jars in my upright freezer when I was getting stock out. I ended up with somewhere around a dozen shattered jars before I just gave up and ordered plastic deli containers specifically made for freezing. I didn't want to use plastic, but I was left with no other option. I was so confused about why my jars were breaking--I'd seen so many blogs from others who talked about freezing their broth in glass jars--that I took to scouring the internet for explanations and others who had experienced the same thing. And that's exactly what I found.
Turns out, many others had made the same mistakes as me. Someone, in one blog's comments, politely pointed out that the regular mouth jars seem to be most prone to breaking, but that NONE of the quart Ball jars are freezer safe. Sure enough, I went into the pantry and pulled down an old Ball jar box that I had kept, and it did state that the quart jars (all types) are not freezer safe.
Why on earth not?? You mean in all of our technology, we cannot engineer a freezer-safe glass canning jar? On GAPS, broths are too valuable to lose to broken jars, and I just can't chance drinking broth and finding a shard of glass when I try to swallow. Glass canning jars can withstand extremely high temperatures when canning, but they apparently become too brittle when frozen. Turns out, the shape of the jar might have everything to do with it.
Anyone who knows about jars (which is probably a group of about ten people on Earth and includes me) will understand that the shoulders of the jars are likely the culprit. Shoulders of jars are the curved or sloped shape of the top of the jar, at the spot where the jar opening narrows to accommodate the size of the lid.
|No shoulders on this jar!|