I spent the entire day removing the bellows cloth from a Duo-Art roll
motor.  It had been glued with the wonderful carpenter's glue that was
extremely popular in the 1970's.

How many times do we come across a piano today that someone else worked
on and curse that person for not using original materials?

On the other hand, how often have we found a material that works as
well or better than the original?  I can think of only one example: I
used a synthetic cloth for the stack on my Ampico.  We will see how it
holds up in 80 years.  Also, how much of an improvement can it possibly
be?  For my Welte and Duo-Art that I'm currently rebuilding, I went
back to regular pneumatic cloth.  It's easier to work with and has a
longer track record.  And frankly, it simply sticks better with hot glue.

There is no end to possible materials that can be used in a piano.  I
still remember as a child going to an ice cream parlor which had a
player piano with the top panel replaced with Plexiglas and the roll-
motor tubing replaced by a garden hose, held with an automobile hose
clamp.

Eli