Tim Gautreaux asked about sealing thin kangaroo skin.  Personally,
I would not normally use skin that thin (but it works great for the
internal pneumatics on a Schultz), but if I did it could be sealed
very easily using Dow-Corning 3140 Flowable Silicone, which is a
non-corrosive silicone sealer intended for the electronics industry.
It does not have the acetic acid (vinegar) odor, and is very thin,
permitting it to be applied to a leather pouch or pneumatic with
a finger tip, then wiping off all excess coating.

The Dow-Corning 3140 sealer cures at room temperature and leaves
a very thin but tough film on the outer portion of the leather.
I tried water-thin RTV, but this soaks into the skin and cures,
leaving the leather much stiffer than desired.

Dow Corning 111 silicon grease is not good for very thin leather, as
it will fill a pinhole, and then the vacuum will pull the grease out,
leaving the pinhole open.

I have been using the Dow-Corning 3140 for the last 10 years or so and
have experienced excellent results.  For the last three years, my shop
has only used "thin" kangaroo skin for the striking pneumatics, and
applying Dow-Corning 3140 not only to seal but to preserve the leather
from the effect of the pollution in the atmosphere.

Anyone wishing more details on how we apply, please visit my web page
or drop me a email.

Al Pebworth - Pebworth's Player Piano Center
Chesapeake, Virginia
http://www.pebworths.com/