Thanks, that's a good tip and I'll remember it. I don't think that was the cause in this case. I canned others just a couple days ago, with different lids, and tightened the way I always do. Just crappy lids is my guess.One tip - make sure that you are not over tightening the rings.
I had the same issue with anchor hocking lids two years ago when water bath canning. That happened to one jar, and a high percentage of my jars didn't seal. I refuse to buy that brand lid again.Had a major canning fail yesterday. Never had anything like this happen before. Opened a new case of canning jars that came with rings and lids. They were Anchor Hocking brand sold by Walmart. Went through the usual steps and when time was up and pressure released I opened the canner. Found jars that looked like this:
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All were sucked in as if they had sealed - but with those "puckered peaks". I could pop the lid on all but 1 with just my fingers. Guess I'll be re-processing with new lids or maybe just toss 'em in the fridge. Grrrrrr!