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MMD > Archives > April 2005 > 2005.04.07 > 03Prev  Next

Relative Humidity and the Player Piano
By John A. Tuttle

Hi All,  During my time as an apprentice, I worked in a store that sold
Steinway grands.  One day I asked the owner why Steinway had such an
odd hinge on the lid (the part that flips over).  He said that the
hinge was designed to allow for changes in temperature and relative
humidity.  Not really believing him, I quietly ran a test and measured
the width of the top in the middle of Winter and again in the middle of
Summer.  Sure enough, it was different by just over 1/16 inch.  I never
forgot that lesson.

All organic materials grow and shrink with changes in temperature
and humidity.  In the case of wood that is well sealed (or finished),
heat causes the majority of the change, since very little humidity can
get into the wood.  With wood that is not well sealed, humidity is the
main culprit.

In most player pianos the internal wooden surfaces were not well sealed,
and in many cases they were not sealed at all.  However, the wood was
fresh and contained enough moisture to work adequately.  As the wood
aged, it became more porous.  Also, even if the wood was sealed, the
sealer developed microscopic cracks because it too dried out.

This combination of old wood and cracked sealer is a primary reason
why older player pianos (that have not been well restored) seem to work
fairly well in the summer but rather poorly in the winter.  Making
matters worse, very few rebuilders will replace every single gasket in
the mechanism.  So, when you add all three factors together, you get

One of the hardest situations I face as a player repairman is
convincing people that I need to seal the wood and replace the old
gaskets to get their player piano working again.  They (the customer)
can't see or hear the problem and I can't prove I'm right without
actually doing the work.  So, it all boils down to a matter of trust.

What I've learned to do is to start with a very simple device, like
a bass or treble soft pneumatic or an auto-sustain.  When I feel that
the customer questions my honesty, I don't hesitate to involve them.
I remove the device, hook up a couple of hoses, and show them how to
test the unit.  Then I let them test it.  Then I take it apart, seal
the wood and replace the gaskets -- right before their eyes.  Then
I put it back together and let them test it first.

Even a person who knows nothing about how a player piano works can
instantly tell the difference.  From that point forward, the only problem
is whether or not they can afford to have the rest of the work done.

John A Tuttle
Brick, New Jersey, USA

(Message sent Thu 7 Apr 2005, 12:46:28 GMT, from time zone GMT-0400.)

Key Words in Subject:  Humidity, Piano, Player, Relative

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