Hi
Heres what I found that might help. Years ago there was a product called aztec clay. (you see it in old tobacco jars) I found a large piece and smashed it apart. I wet it and placed a small piece in my snuff cbox When used with cigars it would give out moisture and take in moisture when needed.Also. I took a viking tin and put a can of cope in it. For some reason it stays fresh longer.
by the by. please forgive any mistakes as i am legally blind