Thanks to Bob Taylor for his insight on sponge neoprene.  I marveled
at the reports of sponge neoprene being of sufficient quality to be
able to be used in reproducing pianos.  It obviously did not come from
Durrell Armstrong at Player Piano Co. and it did not have the peel-
and-stick adhesive that crawls around on whatever it sticks to.

I have another question about sponge neoprene: how firm is it?  Because
when I experimented with it, I noticed that it was so flimsy that you
basically could not have such a thing as uniform valve travel.  It
compressed so easily it was hell to adjust travel.  Is your quality
sponge neoprene more compression resistant?

Also, neoprene is a synthetic substance that has a limited life span.
The tracker tubing is not even neoprene, it is Santaprene.   We know
that the tubing only lasts about 25 years and may get hard before that.
I do not know the difference but Durrell calls it neoprene anyway and
always has.

I wonder if perhaps the sponge neoprene used on Bob Taylor's reproduc-
ing pianos is not neoprene at all, but natural gum rubber.  What makes
me wonder at this is the fact that you must keep it out of sunlight.
I have never had problems with neoprene in sunlight, but I was told to
keep gum rubber out of sunlight.

I put a piece of natural gum rubber on the worktable by the window in
the morning sun and found after a month or so that it got hard and
developed a skin.  This outer shell would crackle if you stretched the
material, as if the shell no longer stretches at all, but cracks
instead.  I now keep my gum rubber and the new quality Australian
pneumatic cloths _out_ of the sun and covered with a cloth.

Perhaps if you still have some of this substance, we could test it to
see what is in it.

D. L. Bullock    Piano World    St. Louis

 [ I'm growing concerned: are you guys all talking about the same
 [ "sponge neoprene"?  Sponge rubber products can be closed cell
 [ or open cell, and many gasket products called neoprene, which
 [ look and feel like neoprene, aren't made of DuPont Neoprene(tm)
 [ or equivalent polychloroprene; they are likely to be a blend of
 [ materials.  You'd should verify that your differing experiences
 [ really happened with identical materials.  Exchange some samples.
 [ -- Robbie