I'm not sure what you mean. Everything that goes into a water bath canner should be near boiling hot. "Hot" and "cold" pack generally refer to pressure canning, or stuff that will be stored in the fridge. I'm probably not understanding what you wrote.
"The jars I put into the fridge always seal on their own."
Because they cool. When you put something hot into a jar, as it cools the warm air and contents of the jar take up less space and it will pull the button down on the canning lid. There is probably not a vacuum on the jar as is created when the jar is placed in water and the air escapes.
"Mostly with the whole “sheeting” thing - takes a practiced eye - and I got panicky about it this year, LOL."
If you are making jelly with Sure Jell, don't worry about the sheeting, just boil hard for one minute prior to adding the sugar and boil for one minute after adding the sugar. If you followed the recipe there is little chance that your jelly won't set.
If you are cooking your jelly or jam without adding Sure Jell, you have to pay attention to sheeting.
I am so glad that you are taking up the practice of canning. There are so few that do it these days.
The pickling brine is ‘bout boiling when I pour in into the jars of prepared cucumbers. Hot pack - according to what the instructions call it.
The refrigerated jars do form a seal - you have to pry the lid off and it is definitely a vacuum seal. I hot pack them, put the lid and ring on immediately, let them cool for a little, then into the fridge. Where the lid pops down and forms a vacuum. Has every time I’ve done it that way so far.
Following the directions on the Sure Jell.....(I don’t EXACTLY).... it calls for a huge amount of sugar, so I have to wiggle it around to get to the amount of sweetness/full fruit profile, that I am looking for. It’s a personal preference thing, but yes, it makes doing jelly more of a challenge for sure. And it means that the sheeting is very important or I don’t get the proper set. There is a “low sugar” Sure Jell, but I haven’t found it locally yet, so I am left to experiment. I’m close, but need another season.
I want to learn the lost things, even if I have failures, because someone has to pay it forward. Yes?