Great discussion regarding sealing pouches.  Thank you all for your
contributions.  I have been struggling with this for years and am now
committed to using thinned PVC-E glue which has, at least in the short
time I have been using it, proven to be a great air-tight, non-toxic
approach.

This technique came recommended by highly respected restorer of band
organs:  Use at least 2 parts water and 1 part glue (as little glue as
possible to get the air tight seal) and then talc.  I am sure that too
much glue could result in stiff pouches.

The best related example is a Duo-Art accordion pneumatic I covered
with medium thick white CPL about five years ago and sealed with rubber
cement.  Recent performance was dismal and after removing the assembly,
sealing with thinned PVC-E and reassembling, it is back to full
expression.

The rubber cement I used (Best Test) has really let me down, being
airtight for the first few months and then getting leaky.  In addition,
I have had a hard time finding this special shoe leather rubber cement
in anything but large quantities that I couldn't begin to use up.

Joel Cluskey