I have 2 open tins. It's difficult to believe that the opened tins are air-tight. So I've been sealing them in zip-locks. I know that they aren't air-tight as well, but I figure putting the tin in a sealed plastic bag, will at least give them a better fighting chance. All the rest, I put in the sealed-lid jars from W-Mart. I just make sure they are very snug. Probably not as good as the screw lid jars, but so far so good after 2 yrs. By the way, even if your toby dries, we can just re-hydrate, right? So no need to panic. Or am I wrong?