Bob Loesch wrote, "You cannot use hot glue with Polylon, but must use a
glue sold by PPCo, and called by them 'Plastic Glue'.  You can use hot
glue with Polylon if you glue with nylon out.  But keep reading.

Polylon was originally made for raincoats and unfortunately it got
snagged by the player piano industry for use on pneumatics.  One thing
that the raincoats package said was that you should not fold them on
the same lines every time you used them as the polyurethane would flake
off and not be water tight if you did.

Now exactly what does the pneumatic do with the Polylon when it
collapses?  It folds it in the same place each time it flexes.  This
was back in the days when Durrell said that we would "not be able to
get pouch leather in a few years, so you _have to use this_ Perflex.
It is polyurethane, and so Polylon is also great because it too is
polyurethane."  I quote Durrell when I say:  "Perflex and Polylon will
last for hundreds of years."  I am sure he believed it when he said it.

Well, rebuilders believed and we used the stuff.  I was leery of it
and so only did my own pianos, which have now been rebuilt several
times using all experimental materials before finally being done in
leather and rubber cloth.  I am glad now that I did not do any
customer's pianos.

In 1970 I did the whole Duo Art system in Perflex and (God forbid)
sponge neoprene (another disaster).  Perflex was popping like balloons
on pneumatics.  I then recovered the pneumatics in blue Polylon.
I found that the Polylon just crawled off the pneumatic boards.  I had
glued to the nylon cloth side.

I then covered them with red Polylon.  It took less than a couple
of years each time to find that the Polylon flaked off the pneumatics or
the nylon crawled off the boards. I found that the Perflex lasted 6
years on pouches before it developed crescent shaped holes in them.
I recovered the pneumatics with Durrell's cotton pneumatic cloth and
after ten years, they were crunchy -- obviously a neoprene, santaprene,
or other synthetic rubber coating.

I later recovered them with better cloth, but now I have found the
Felix Trading Australian cloth using natural gum rubber.   I use that
only now because of the several examples I have found of 70 year old
natural gum rubber that is still as good as ever.  The pneumatic cloth
I have found with gum rubber on it still needs replacement because the
cotton cloth has broken down, but the rubber is still good.

In the last 15 years of player and pipe organ work, I have spent more
time replacing Perflex and Polylon (and "new" vegetable-tanned leather)
than I have spent replacing original leather and cloth.  I have a bag
in my files of samples removed from various instruments.  I have
yellow, maroon, black, gray, blue, red, and tan Polylon all showing
a catastrophic failure for air tightness after only a few years.

I had an old rebuilder working for me a few years ago who insisted on
purple Polylon from American Piano Supply, and I must admit that it is
the _only_ Polylon that I do not have in my "failure" file.  I suspect
that I will find such an instrument someday, but I can truthfully say
I do not know if it will fail like all the others have.

One problem I find beyond the problem of longevity is using the
Polylon on striker pneumatics' hinges.  It allows them to be very
floppy.  I prefer a solid hinge that will not allow sideways movement
of the moving board of the pneumatic.  When I did cover in Polylon
I used hot glue and cotton for the inside hinge to prevent this
problem.  The problem is lessened but not completely gone.

One thing that is true for anytime you glue with PVC-E glue is the
surface _must_ be completely devoid of old hot glue.  Many are the
examples of rebuilders not sanding pneumatic boards leaving old hot
glue and then gluing PVC over it.  This causes a chemical reaction that
makes the white glue dry initially, but later it turns into jelly that
oozes off the board.  It is a faster version than that of PVC and nylon
doing the board crawl.

I have learned to not use any synthetic materials in my restorations.
I have finally found the top quality natural gum rubber cloths from
Australia and chrome tanned pouch leathers and I will stick with them
as long as they are the proven longest lasting materials available.

Felix Trading will sell only to Schaff Piano Supply and Organ Supply
Industries in Erie PA.  You should specify Australian cloths or
leathers when you order.  I buy pouch leather from Columbia Organ
Leathers in Columbia PA, who supplies it to most of the other
suppliers.  It comes in 6 thicknesses and is FAR less money than PPCo.

Having removed PVC-E glue from many surfaces, I suggest you throw the
boards into a bowl of lacquer thinner to remove old PVC glue.  It turns
the glue into jello which will rub off in 10-15 minutes.  Then sand the
wood.

D. L. Bullock    Piano World    St. Louis