alcohol is hydrophillic. It could actually make your snuff drier than it already is. Id think non contact rehydration would be best. in a tupper ware container place your open snuff can, and something holding water. You should get diffusion, especially if the container is somewhere with a little of heat to get the humidity up inside the container.
So you could in effect steam a snuff in a chamber with a cup of boiling hot water. Has anybody tried this? It sounds like a quick way to rehydrate a small tin.
I don’t see why it wouldn’t. I’m sure it would work better the more surface area you have, like pouring the snuff out of the tin onto a plate or something. This would be the best way, as the steam is essentially “distillied water” you wouldnt have to worry about minerals either.
My concern with directly adding water which is a solvent to your snuff is that it would wash away nicotine and flavoring off of the snuff it initially comes in contact with into higher concentrations around the edges. I think it could also change the consistency of the snuff.