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MMD > Archives > March 1999 > 1999.03.24 > 08Prev  Next


Silicone in Pianos
By Craig Brougher

Don Teach was very adamant about silicone "creeping" in pianos.  I am
going to be very direct and to the point about this, since this is a
misnomer believed in many quarters, and I think I know where it comes
from.

In the first place, the only two ways silicone is able to "creep" is:

1.  If it forms a low enough vapor pressure and "evaporates" under
vacuum or low pressure conditions to re-deposit itself all over (like
Vaseline and other oils and greases usually used in players) or,

2.  If the wood is able to "wick it up," and it can travel through the
wood like an oil does.

There are thousands of "silicones." I have yet to find one that will
float on water, however.  It is a highly insulative, waterproof, and
stays put.  It does not create a vapor pressure or migrate like any
oil.  In other words, exactly the opposite characteristics of oil and
grease actually.  Its a big molecule, compared to skinny, small ones.
You'll never go wrong if you just go back to the basics and ask, "How
can that be?"

The way this all came to be believed (and you know how difficult it
is to get something out of your mind, once you have come to believe it)
is because there have been and are still, many products listed as
"silicone" which are not.  For one really GOOD example, take
"Sil-Glyde." That is sold by the Player Piano Co., and supposed to be a
silicone grease, but it isn't.  It's just plain grease, with a smidgen
of silicone in it.

Pure silicone oils and greases are clear -- like water.  (Not that
clarity is your proof, since Vaseline is also clear.)  One of their
characteristics is, they do _not_ migrate!  They stay put, just like
they do on the space shuttle in a perfect vacuum.

For example, silicone has long been used as mold release agents.  Once
a mold has been coated, it won't have to be recoated again for perhaps
thousands of operations.  Before this, greases were used that had to be
recoated every few times.  Why?  Because it migrated into the part
being molded, primarily.  It was removed by surface tension, and just
scraped away.  Whereas, a fine mist of silicone or TFE would stay put.
That's its primary characteristic.  It is an insulator, a waterproofer,
and a lubricant for porous, soft materials because it stays on.

On the other hand, the old builders of automata often used lubricants
like petrolatum and other greases which did actually coat things inside
a piano, and if the repairman or tuner overused these products, they
would eventually find their way onto the strings and pins from
vaporizing.  This, in turn could ruin the ability of the piano to hold
tune, or the ability of a tech to glue an action back together.

You still see this in old commercial instruments that ran day and night
with nickel slots.  But since it is physically impossible for silicones
to repeat that performance, I'd say it is a step up, not down, and de-
finitely has a permanent place in automatic musical instruments since
it does not soak deeply into the side grain of wood.  (On the other
hand, anything at all will soak into open end grain.)

You will notice that while oils leave dark oily spots on wood where
they have penetrated, even right through a finish, often as not, pure
silicone does not.  That is its main characteristic.  Otherwise, it
could not be used as a waterproofer, an insulative barrier, and a lube
for soft, porous materials.  (The basics win every time.  Trust the
principles.)

Craig Brougher


(Message sent Wed 24 Mar 1999, 12:56:04 GMT, from time zone GMT-0600.)

Key Words in Subject:  Pianos, Silicone

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