Hello All,  I was considering responding to the contribution about the
airtightness of fuzz back bellows cloth which appeared recently in MMD.

Since I had just completed several projects using this material, with
as-expected good results, I decided to do some experimentation to
attempt to recreate the problems described.  I found that, when glued as
we old timers were taught to glue fuzz back bellows cloth (and the way
the original builders glued it), the stuff is absolutely airtight,
including from a hole through the fuzz (glue filled!) to edges as close
as 1/4 inch.

This process involves double gluing and ironing the cloth to coax the
glue to migrate up to the rubber and fully saturate the fuzz.  _All_
original bellows cloth was glued with the fuzz saturated with hot glue,
and we all know how well it stuck in place.

On the subject of hot hide glue, I have a customer who has a 1925
Steinway OR, a 1928 Knabe Ampico, and several other players which have
been restored with original techniques and continue to play flawlessly
and trouble-free year after year, even though they are in a building
in Maine with no central heat.  They see winter temperatures well below
zero.  They are not subject to condensing humidity, however.  Every
spring they return to full performance and even work well on occasional
winter days when the owner braves the cold to play them.  The Knabe was
restored about 15 years ago and has played thousands of rolls.  The
Steinway is on its fourth year after restoration.

Properly glued bellows cloth or pneumatics will not leak at the glue
joint for many, many years.  _Please_ be cautious with replacing tried
and proven original methods.  The best thing we can do is to restore.

Thoughtfully,
Bob Hunt
Kennebunk, Maine