If you are planning to get leaves from WholeLeafTobacco, they're already properly aged and will stay fresh in the vacuum sealed bags for up to a year. Of course, opening the bags and shredding the tobacco means you'll have to find your own means of keeping the tobacco fresh. If you are planning to get leaves from somebody else, you'll have to ask your seller about "shelf life" and aging.
I have several pounds from the that other supplier but I plan on buying from Don from now on for several reasons one of which is the way he ships his, the condition of the leaves, particularly the larger varieties is like night and day. Its harder to remove the mid-stem and shred leaves when they are practically wadded up into balls. Anyway, they claimed everything was aged properly. The amount of tobacco we've been going through, I don't think I'll ever have a years worth put away
, however I've wondered if we're smoking better tobacco if we'll smoke less. Time will tell.
Don sells the vapor proof bags. I also reuse the ones I get tobacco in by using clothes pins to reseal. You can seal them back with an iron or curling iron, but you lose bag length each time you cut the end off.
http://www.fairtradetobacco.com/showthread.php?418-Vapor-Proof-Bags
To your other post, I'll have to keep that in mind about oxygen and aging. To be honest, I was thinking more of the tobacco getting moldy or something. The bags I have everything in now could be opened up to let the vacuum out and resealed.
As far as the bags, I could use either the ones I have already, we use them for freezing raw and even some cooked foods. I have some that I can fit well over a pound after it's been shredded. But the bags Don sends his tobacco out in are good, in some ways better than the thinner vac. bags, I could shred and just store in those. Thanks for sharing that link to the bags.