I can orange marmalade once a year (maybe), so I'm not very experienced. Last year I started experiencing a problem with seals popping, and it is happening again this year.
The jars all seal, and everything appears great. Then about a week out, one pops up, then a week later, another... and before long 10 - 20% of my seals fail.
This year I was a fanatic about cleaning the jars before placing the lids. (The jars and lids are all Ball, all lids are new.)
I boil and simmer the lids, but notice some white hard-water residue and wonder if that could be contributing to the failures.
(I've canned about 15 years and NEVER had any fail - beginners luck I suppose - until now.)
By the way, the lids still hold on tight and I feel like they are still really sealed, but wouldn't dare take the chance, so I give them away immediately and tell everyone to refrigerate and eat right away. It's a drag because these are supposed to be gifts.
Why do they seal initially, then pop up several weeks later? (I live in Florida, and room temp can be typically warm.)