To answer the questions about Silicone Sealant for Pouches, here is my
opinion on what to do about pouches.  Go into the MMD Archives and do a
keyword search on "silicone" and you will get the info on Silicone
Sealants.  This should answer just about any question.

First of all, the original pouches may look good after 85 years, but
they're probably rotten.  Always install new pouches when rebuilding
any player before sealing them.  Also, there usually is a ball of dirt
and dust under the pouches that you can't remove without removing the
old pouches first and then the pouch well should be cleaned and
resealed with new shellac while pouch is removed.

I've been using the Dow Corning Sealant 734 out of a tube diluted about
2 parts naphtha to 1 part 734.  Spread on the pouches after installing
new pouch leather and the disc lifters.  It will be dry in a few
minutes and I don't see any need for talc powder.  When it is dry,
there is no stickiness.   Since Dow guarantees this stuff for 50 years
or so, I don't think there will be a problem with it deteriorating.
And the pouches are still very flexible after application.  It is also
very air tight.

We need to consider here that rubber cement is consumer grade quality
and Dow 734 is industrial quality level sealant.  I would prefer any
industrial grade materials over the local hardware store consumer grade
materials.  I buy as little as possible of my player rebuilding
supplies from my local hardware store.  I mostly buy from industrial
distributors.  Just an opinion.

Bing Gibbs
Player Piano Forte
Cupertino, CA