Colin Hinz was wondering:

1. > Question:  Were the failures, that were experienced with Polylon
   > and hide glue, gradual failures or immediate failures?

The failures of bonding appeared (to me, at least) immediately.  If you
will take some compressed air, regulate it to 25-30 lbs pressure, put a
rubber cork on the end of your air gun and inflate a pneumatic with it,
it should hold.  All the ones that pop, you can fix the weak spot and not
lose it.  Test those again the next day.

Twenty-five years ago, before I knew the value of testing everything
first, I covered a set of pneumatics in a "Simplex" grand action stack
for a Recordo that eventually failed big-time.  Had I tested first, it
would have been apparent.  But some of the pneumatics were literally
hanging open.  It was a real mess.  That was when I started disliking
plastic glue for pneumatics.  The stuff offers no hinge support.  And if
you use it for Schultzes, with their lost motion stop at the back of
every hinge, you are putting a constant weight on the hinge end of each
pneumatic, and they will slip right out of their covers, using plastic
glue -- even under the best of conditions and cotton/rubber cloth.

2. > If things appear to work out well initially, is it safe to expect
   > the glue bond to last the lifetime of the Polylon?

Sure.  Whatever you do, either with leather, cotton and rubber, or
Polylon -- test it first.  Things are different from batch to batch.  The
next batch of Polylon could have mold release on it.  I remember a batch
of cotton/rubber that wouldn't even glue to itself at the back hinge! The
hide glue would bead up just like it was sitting on paraffin wax or
something.  Ridiculous -- but we have to deal with this kind of thing.
Don't trust anything!

I just recently got a Coinola X to restore, and the pump -- which had
been rebuilt thoroughly by an otherwise expert restorer obviously --
didn't work well, because I found the leather at the overlapped hinge end
to be not well bonded.  The leather was a satin finished calfskin, and
was either waxed or lacquered, or both.  To glue to finished leather, you
have to scuff the finish off of it.  The flap valves had been glued down
to metal flap spring plates, too, and they just zipped right off.  But
frankly, they work better if they are only attached at points along the
plate or at the ends only.  By gluing then down, you increase the power
needed to open them up, which subtracts from the instrument under heavy
load.

My suggestion to anyone who wants to use Polylon or any new material they
have just received in is to take the time to test it, first.  And don't
rush it.  See if you have any problems.  And if you are able to, use the
compressed air test.  That way there is no questions at all.  If you have
an adhesion problem after all, try wiping the cloth on the Polylon side
with lacquer thinner and gluing it again.  Try a few things first.
Gluing Polylon is really easy, but you should glue the sealant side in.
That puts the nylon out.  It protects the sealant, which is more fragile,
and glues more tightly, too.  You can't remove the cloth without leaving
the sealant on the boards.  Believe me, it's stuck very well.

One last comment about fish glue, by the way.  I like the LePage's' Fish
Glue for many things.  Some rebuilders use it for pneumatics.  I have no
problem with that.  I personally like the highly brittle, non-elastic
properties of hot hide glue, and doubt that I will ever change, but
applying fish glue is easier.  You don't have to worry about consistency
or keep adding water.  And you can buy these nifty little accordion
applicators with a thick needle from Woodworker's Supply that will apply
it.  Larry  Broadmoore uses this glue, so I suspect it's just fine.  The
fact that it never gets as dry and brittle as hot hide glue is shown by
the fact that it retains at least 10% of its moisture content after
drying-- according to the manufacturer.  But it still may be sufficiently
hard to positively support hinges under constant load conditions, too,
and not creep.

Again, before I make any claims, I would really have to test it first and
satisfy myself that it is all its cracked up to be.  I just haven't had
time to do that, yet.  When I do, it will be without a standard hinge,
and the cloth will do all the supporting, as in some player systems.
Then, I'll put a constant weight on one end and forget about it until I
either hear something go bump in the night, or it never does.

Craig Brougher