Thanks to all who responded to my post about Bilon bellows cloth
[110626 MMDigest].  Just so you know where I am coming from, lest
I ignite another fire storm, I have been rebuilding players for over
40 years.  I am coming up on probably 100 units of which only about
six have been reproducing grands.

In discussions with other technicians I hear about customers who range
from those who want a historically accurate top quality instrument
regardless of cost to "Joe Six Pack" who wants most of the notes to
play, sort of, for when the neighbors come over so they can have a few
beers and stand around the piano and sing off key.  They might have the
piano tuned every ten years "even if it doesn't need it" as long as it
doesn't cost too much.

Almost all of my customers are closer to the "Joe Six Pack" range.
I feel that a non-authentic rebuild that works is far better than
a player in the landfill, which are often the alternatives.

Over the years I have used both cotton cloth and Bilon for wind motors.
My experience is that with the cotton cloth if the player is not played
for months to years the wind motor cloth will "take a set" and the
shaft rotation is irregular (it hitches or lopes).  I have not found
this to be true with Bilon.  Also I have found that the corners of the
cotton cloth tend to develop holes in the sharp crease faster than in
Bilon cloth.

Over the years both good and bad quality of both Bilon/Polylon and
cotton cloth have bee sold.  I have had experience with re-doing both.
With Bilon/Polylon I do not find them any harder to recover than those
done with hot hide glue and cotton cloth.  I just use a slightly
coarser sand paper to sand off the old glue.  The feel is different
when sanding.

In one memorable case mice moved into a rebuilt piano less than
thirty days old and made a nest of 87 bridle tapes, the cloth from
17 note pneumatics, and 23 front rail felt key punchings.  I invented
the word "phfqqueeek" as the sound a mouse makes going up a 1" shop
vacuum hose!

On further checking my supply of bellows cloth I found that the
rolls of cloth I thought were Polylon are actually good quality Bilon.
I have a good supply and will continue to use it for wind motors,
tracker pneumatics, etc. where they work in sets and where one
pneumatic may stay in the closed position and another in the open
position for an extended period of time if the player is not played,
unless the customer wants, and is willing to pay for, a historically
accurate rebuilding using cotton cloth.

John Dewey