To keep the tobacco in its tin I use a double aluminum foil placed below the lid and cut just below the border of the lid. Then I seal with electric tape between the aluminum foil and the lid. Tin resealed in this way are still as fresh as when originally opened 2 years ago. If you want to add an extra layer of security you can run aluminum tape on top of this. I like to reseal opened tins in this way as it save space and it is easy to recognize different tins easily. For long term cellaring of bulk tobacco Mason Jars are the way to go, while for long term cellaring of tinned tobacco I leave it in the tin and to be safe I run a layer of aluminum tape around the lid.