In my shop, we've sealed leather pouches with Carter's Rubber Cement
thinned with naphtha, for _thirty_ years.  I've never seen a pouch get
stiff, if the solution was thin enough and applied properly, and if the
pouches were dished and glued correctly in the first place, with no
wrinkles, and neither too much nor too little dish.

I'm not saying that the advice given in my book Player Piano Servicing
and Rebuilding is perfect, nor that it's the only way to get the job
done.  But it wasn't based on doing two or three pianos, or twenty or
thirty.  It was based on over 50,000 hours of repair and restoration
work that my employees and I had done by the time I wrote it in 1985.

Obviously, not everyone does everything the same way, and there is
more than one way of doing certain things well that produce excellent
results.  I've always been open to alternative materials and methods,
and over the years I've tried most of them at least once.  Over half
of the restorations that we've done have involved re-doing work that
was done with materials that had failed and/or work that just wasn't
precise enough the first time, always at greater expense than if the
job had been done right the first time.

In 1971, I restored the player mechanism for a mint Wurlitzer BX
for a local antique dealer, using thinned rubber cement on the pouches.
This orchestrion stayed in high, dry Estes Park, Colorado for about
five years, receiving no more than a few thousand plays.  Then it was
sold to a party who used it commercially in the San Francisco area,
where it was so damp that the original poplar back panel covering the
soundboard and back assembly was ruined by the moisture.  There, it
played over 50,000 times.  Then it came back to Colorado, where it sat
unused in an extremely hot, dry warehouse for three years prior to our
giving it a thorough restoration.

Curious to see what effect these extreme conditions had on the pouches,
and fully aware of the rubber cement controversy that's been going on
for at least 20 years, I tested them carefully.  They were just as
flexible and airtight as they were in 1972.  I removed the pouch from
the snare drum unit and sent it to Durrell Armstrong, who prefers to
use mink oil, a product that he sells.  He admitted that my pouch was
in fine condition but said words to the effect that "just because I had
good luck with it doesn't mean other people will."

In my opinion, no type of silicone has any place in a piano.  It
creeps, crawls, goes where you don't want it, and is extremely hard to
remove.  Thirty years ago, a major piano company service representative
noted that certain new pianos needed to have their pinblocks replaced
after their owners sprayed furniture polish containing silicone in the
vicinity of the tuning pins, ruining the pinblocks as the silicone
crept down into the wood.

Similarly, the idea of applying oil anywhere near wood gives me the
creeps.  I've spent altogether too much time replacing oily wooden
parts in old instruments because leather wouldn't stick to them
any more.

Carter's was good enough for the American Piano Company to recommend
its use, and it hasn't caused me any problems yet.  Just apply it so
thin that it doesn't stiffen the leather, make sure all of the wood is
sealed properly, and above all, don't drag any glue onto the working
area of the pouch! I've seen more pouches that were reluctant to lift
their valves due to a very small amount of glue on the leather than for
any other reason.

Art Reblitz