Cellaring your tobacco collection is pretty simple. Mason jars, or factory sealed tins. Done.

But what about short-term storage of your baccy once you pop the seal after aging it to perfection all those years? If you had it stored in a mason jar, viola, just put the cap back - and open as needed until the contents of the jar are exhausted (or you are exhausted, whichever comes first).

Tins on the other hand, are a different animal. Several different animals really. Round screw on tins like Escudo are pretty good for re-closing. Even though the seal has been popped, you can still keep baccy fresh (while using it) for several weeks - simply by screwing the cap back on tightly. Care must be taken when popping the seal - use a dime or similar sized coin to ease the seal apart (giving the POP). Don't hammer the lid off and bend it, or it will not close back tightly again.

The GL Pease and C&D tins, with the pull off caps, will never seal air-tight with the supplied plastic "hat". Ditto with the rectangular/square tins such as Samuel Gawith. Both these kinds require a little ingenuity, and this idea comes from Greg Pease's posting somewhere, sometime ago.

Take regular kitchen aluminum foil. Tear off a piece that is much more than twice the opening of the tin you have popped. Yes, new foil only. Don't be cheap and try to reuse the foil from roasting your turkey. Fold the foil in half, so now you have a 2-ply sheet that is larger than the opening of the tin. Place this double layer of foil over the open tin, about centered so there is an even amount of slack all around. Take the lid, and jam it on (without tearing the foil). Magic, you just resealed the tin! This can last several weeks while you burn the contents of the tin. Note that each time you open/close this foil seal, you do weaken the foil, and it will become lesser and lesser efficient in locking in your baccy freshness.

Personally I also throw the whole tin into a suitable sized ziplock baggie (genuine ziplock only!) and zipper it shut. It may help keeping moisture from seeping in/out. Ziplocks by themselves are only good for keeping baccy fresh for a few days. But doubled with the foil ploy described above, I have retained opened tins for nearly a year this way without too much drying out occurring. An additional benefit of the ziplock is to protect the tin contents from an accidental "oops, I dropped it". Rather than have to sweep the contents of the tin off the floor (and smoking it anyways) - everything will be neatly collected within the retaining ziplock baggie. Now you can see why I often have twenty or more open tins at any given time!

Factory sealed tins, usually, are perfect for cellaring as-is. However, three bad things could happen to tins during long term storage. The tin seal could get compromised, and thus result in dried out baccy after years of patient cellaring. Or the tin could catch rust and disentigrate, with the same dried out baccy results. Or the baccy inside could "over-ferment" and make the tin swell to the point of exploding. These bulging tins should be opened (carefully!) immediately and the contents, if not spoiled, transferred to a mason jar to resume their cellaring nap; or consumed expeditiously.

Different kinds of tin seals can be tested in different ways. Square/rectangular tins like Samuel Gawith stock are easy to check. They are basically held together by the vacuum of the seal, when compromised the lid just falls off. A light tug on the lid will quickly reassure the cellaree about the status of its seal. Round pop-off tins such as GL Pease's stock are much stronger in maintaining their sealed state - and it is easier to eyeball the pull-off cap to see if any gaps have opened in the seal/rim. Round screw on tins such as Escudo have probably the sturdiest seals. The only real damage these round tins can suffer is from blunt force impact (typical in snail mail shipping) that could deform the tin shape and pop the seal. Undamaged round tins such as these can also be re-sealed by hand closure during content consumption, remarkable technology.