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MMD > Archives > October 1997 > 1997.10.30 > 08Prev  Next


Re-covering Pneumatics with Polylon
By Craig Brougher

After reading several other remarks about Polylon, I am beginning to
sense that the old product first sold by PPCo has definitely jaded
rebuilders from trying it with hot hide glue.

When I first used that plastic glue stuff on the first run of Polylon,
which was red on one side and white on the other, it didn't stick.
There was some kind of a mold release agent on the cloth that prevented
anything at all from sticking to it!  Until you wiped it down with lacquer
thinner.

A few years later, a new batch was sold that was red -- both sides -- and
it didn't stick, either.  But by then, after one bad experience, I wasn't
going to use it.  Besides, the first batch of Polylon got soft and gummy
after awhile and you could scrape it off the nylon with your fingernail.
It was really junky stuff.  Durrell is still smarting over that one.

Still, after dozens of players recovered with the cotton/rubber of those
years, I was desperately looking for something really good, that would
hold up.  I finally settled on the dark blue stuff that American Piano Co.
sold.  This I have in my own piano.

Before I recovered those pneumatics I made some tests first.  Years
later, before publishing the book on Orchestrion Building and Pneumatics
Handbook, I sent a pound of glue that I was using, plus a number of
covered pneumatics, and pneumatics ready to cover with strips of Polylon
to "What was then" Hudson Industries -- the manufacturer of hot hide
glue.  I got a letter back from them (Jacob Utzig) telling me that it
made a perfect bond with Polylon and achieved its full strength without
problems, void free.  So I reprinted his letter in the appendix on glue
of my (then) forthcoming book.

Depending on where you buy your material and/or what batch it comes from,
I have found it wise to test, first.  And if you still have some of the
second or third batch stuff from PPCo, if it hasn't turned gummy and
sticky, it'll be all right, but wipe it down with lacquer thinner first,
just to get rid of the possible chance that it was coated with mold
release.

Glue the poly side in against the wood, and you will have a wonderfully
strong pneumatic that very easily supports xylophone strikers.  It's all
I've used since, because it will outlast cotton and rubber ten to one.

And if you would rather use a rubber coated cotton cloth, my suggestion
is to use the Australian product from PPCo mentioned by Don Teach.  It's
the best in that category.  However, it will not last as long in any case
as will Polylon.

By the way, if anybody is interested in testing the two products, try
using a reiterating valve setup with a "heavy" load (A spring weight is
good).  Time it first to find out how many cycles it makes in an hour,
and let it run to destruction.  Do two of them together -- one with
cotton/rubber, one with Polylon.

I think you will find that it will take about two or three weeks for the
rubber covered one to show visible signs of wear and losing pressure.
Remove the cover and look at the cotton inside.  You will see the
"stripping out" that comes from working the pneumatic.

Remember, this is in fresh rubber, too.  As rubber ages, it becomes more
prone to this kind of wear, too.  Polylon will not harden with age.  The
Polylon will still be going strong after a month or two.  In which case,
turn it off, because those covers are going to outlast everything else,
anyway.

That is an extreme test which no piano will ever actually have to endure.
The accelerated wear comes from loading it and using a relatively high
(30") vacuum.  It will teach you a lot about pneumatic materials, but
like they say, "Seeing is believing."  So don't take someone else's word
for it.

Craig Brougher


 [ Editors note:
 [
 [ Craig, I know that you 'run' on praise and recognition; and, by golly,
 [ you deserve it!  The "how to do it" articles, and the descriptions of
 [ the thorough testing, are valuable knowledge which you share with us.
 [ Your generosity is greatly appreciated!  :)
 [
 [ To MMD: If you like to experiment with pneumatic systems, or simply
 [ enjoy reading about innovative techniques and devices, write to Craig
 [ for his book, "The Orchestrion Builder's Manual and Pneumatics Handbook".
 [ It's full of good ideas and their applications in pianos and orchestrions.
 [ I've enjoyed my copy immensely, and have given copies of the books to
 [ my friends.
 [
 [ To the World:  Read the copyright notice at the end of this Digest.
 [ MMD authors enjoy seeing their efforts in print, but permission must
 [ be obtained before their articles may be reproduced elsewhere.
 [
 [ Robbie Rhodes


(Message sent Thu 30 Oct 1997, 14:19:12 GMT, from time zone GMT.)

Key Words in Subject:  Pneumatics, Polylon, Re-covering

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