In reference to Mike Knudsen's comment about silicone and leaky leather
bellows, please pop down to the hardware store and pick up a tube of
Silicone Caulk.  Comes in several colors, but clear is nice.  This is
generally separated from the rack of caulks you would use around loose
boards.  Warning: some of them say things like "contains silicone."

Silicone is a lot more expensive than linseed oil and clay, and there is
some coattail riding going on there.  Nice clear silicone caulk will set
up to rubber from the moisture in the air and it is very stable.  Try
some globs here and there, and try diluting it with a little lighter
fluid and see it still sets up.  There surely is a solvent that will
thin it without killing the cure.  Keep it in the refrigerator and it
will keep years.

This stuff is so neat to use, I think it would be nice if everyone could
play with it a little.

Allan Merralls