I wanted to share the results of some tests I made sealing pouch
leather.  The pouches I treated are both organ and reproducing piano
valves.

I began searching for new solutions after finding that pouches I
treated with Craters rubber cement were stiff when I checked them
10 years later.  I have experimented and experienced promising results
sealing pouches with Golden brand high viscosity gel gloss painting
medium.  This can be purchased at any good artist's supply store.

The gel comes in jars and is a creamy constancy which can be rubbed in
to the surface pores of the pouch leather with one' fingers.  It does
not wet the leather too much and forms a thin very flexible glaze which
is well integrated with the leather surface.  The leather remains quite
soft and becomes very air tight.

I have not found it necessary to powder the pouches after treatment.
If you prefer to powder them pure 100% talc can be used, obtainable
from Van Dykes supply (http://www.vandykes.com/).  The leather I
treated was certified chrome tanned pouch leather from Colombia Organ
Leathers.

The matte gel is not 100% acrylic and should not be used.  Golden
Acrylic medium is very high quality and has no adulterants.  Other
brands of acrylic reacted with the pH of the leather and coagulated
as they were applied.

I have asked several friends who work in conservation what they
thought about the treatment.  All of them agreed that acrylic mediums
have been around for some time and are widely used in art and
conservation.  Acrylic should not react unfavorably with the leather
and should last for as long as any leather treated with it would be
in service.  We agreed that the sealed leather should theory, outlast
untreated leather because it would protect it from penetration of
acidic air pollution.

If any readers have any pertinent information to offer I would
appreciate hearing from them.  It is my hope that my experiments
will prove to be of help to all people involved in restoration.

Mark West, Baltimore MD