I’ve gotten this question several times; since I posted the answer in a comment a while back, I think most people haven’t seen it. So I’ll put it up as  a post to make it easier for everyone.

>>so, i have a few preliminary questions for you, when you have time to answer. first, how do you deal with kashrus with used mason jars? i will ask our rav, but i am wondering how you hold on kashering, etc. <<

We kasher used jars – you need to make sure they’re spotlessly clean and then completely submerge them in boiling water.  It doesn’t matter what they were used for before.  This was what we were told by Rav Moshe Heinemann, who is head of the Star-K kashrus agency.

>>second, do you know if a pressure canner can be used for both meat and dairy? again, i will ask our rav, but am wondering what you do.<<

I don’t use it for both, only for meat, because the jars don’t seal until after they’re out of the canner.  Until then, juices leak out and make the pot very definitely meat.  There’s very little that most people would can which is dairy, so only using a canner for meat doesn’t present much of an obstacle.  The only dairy thing I’ve canned is butter, and that doesn’t need a pressure cooker, just a standard large pot for water bathing. 

>>third, have you found a use for the screw on lids for the mason jars? when i buy new round things that seal the jars, they always come with the screw on parts too, so i am getting an increasingly large pile of gold bracelet things. do you do anything creative with them?<<

Oh, good, now I can help you save some money.   Stop buying the packages of lids that come with rings!  You only need to do that in the very beginning, since the rings are resusable.  More of them just creates clutter, and who needs that?  What you need to look for instead are the boxes that have only lids – they contain 12 lids each and average in price at about $1.50 – $2; they look like this (this is an affordable online source – I bought a case from them last year).  Since it sounds like you’re aquiring a large collection of bands, put most of them away in storage, and bring them out when the ones you’re currently using start to get rusty and need to be replaced.

Avivah