Pat DeWitt posed a question in MMD 060209 about sealing pouches in
Ampico secondary valves.  Specifically, the question of gluing the
lifter disk to treated pouch leather was addressed.

One method that can be used is to place a small masking tape dot on
the pouch leather center.  Apply the sealant and remove the dot.
This small area now is untreated and normal glue operations can take
place.  Usually a dot created by a 1/4-inch punch will work.  Also,
small self-adhesive colored dots can be purchased at most office
supply stores.

In general, pouch sealing is performed to assure that the design bleed
balance point is maintained.  Secondary Ampico valves have no bleeds.
The pouch well is exhausted through a 5/32 connection to the primary
valve which will overcome any natural pouch porosity.  Some overall
system vacuum "consumption" may be reduced by sealing the secondary
valves.  The "consumption" occurs only when the leaky secondary valve
pouch is "on".

Bob Taylor
http://members.socket.net/~rtaylor/aeolian_pipe_organ.html