I have decided that the gasketing of the pneumatic decks was basically
for the purpose of preventing the pneumatics from sliding around when
they are planted, enabling the builder to use thinner hot hide glue,
creating a better seal in general on pneumatics which may be warped,
for more tolerance to particles in the glue or on the pneumatic or
the deck, and for a much faster "grip" time. The negative aspect of
gasketing is its intolerance to be removed or moved even slightly if
the pneumatic was planted wrong.
It definitely should not cause the pneumatics to fall off easily.
Just the opposite. So, if some pneumatics seems to fall off when pried
lightly, that is due to some other factor.
Aeolian Duo-Art used pneumatic skins to glue their pneumatics to, and
these are very easy to remove. Not because of the glue, but the skin
itself, which has, in the process of time, dry-rotted. It looks
perfect, but the pneumatics will just fall off of it.
Ampico Amphion stacks and others used stiffened (sized) cheesecloth
strips, with which they also covered the pneumatic feed hole. These
are very difficult to remove compared to the Duo-Art, because the
cheesecloth didn't rot away.
Whatever you discover was used as a gluing gasket, you have to get rid
of every bit of it. I have redone some Duo-Arts whose former rebuilder
scraped off as much old pneumatic leather as he could get off that way,
then glued the recovered pneumatics back down directly to wood. He
thought the new glue would saturate the old leather colorations right
on through, down to the wood, and it would be all right. Not so. The
pneumatics which fell off or were loose one side and leaked had the
coloration of the old skin under it.
The best way to remove that is first by scraping, and then wetting it,
letting it soak a short while, and then just rolling it off. You can
get 100% of it off that way.
Regarding the use of water on any kind of glue joint, that isn't wrong
to do, contrary to many hobbyists' opinions. Like they say, "The
poison isn't the product but the dosage," the same balanced approach
applies to everything. If you leave parts soaking too long, you are
just asking for it. But glues all have water in them, and they don't
warp the wood-- unless you are using either the wrong glue or using it
in the wrong way. So dampening or wetting parts first can be a good
technique. Just don't overdo it. If you don't know or are leery about
it, then test one first.