as doors and drawers become tight with
high humidity and loose in dry air, the
keys of your piano may stick down when
struck in times of high humidity. When
the environment surrounding your piano
is dry the keys may seem to rattle when
you play your piano, you will notice how
responsive the keys are to your touch.
The way the keys cause the hammers to
strike the piano strings is part of thousands
of interconnected wooden parts called
the piano action. With high moisture levels
in the piano action, the action is sluggish,
and the keys seem non-responsive to your
Bridge and Soundboard Damage
is the single largest piece of wood in
your piano. It actually vibrates to amplify
the sound produced by the strings. The
bridges of your piano are joined to the
soundboard and support the strings.
the soundboard absorbs moisture from the
air surrounding the piano, it swells,
producing an upward bulge. Through the
bridge, this puts additional tension on
the strings. Now, the pitch is too high
in the lower mid-range and treble section.
the soundboard shrinks and flattens, the
tension of strings over the bridge becomes
inadequate. The pitch of the mid-range
and treble section is now flat.
time, constant changes in humidity levels,
with the corresponding shrinking and swelling
of the soundboard, will damage the integrity
of the soundboard. You will see this damage
in the form of a crack in the soundboard.
strings of your piano are held tight by
the pins in the pinblock. As the pinblock
absorbs moisture in periods of high humidity,
it swells, crushing the wood fibers against
dry periods, the wood shrinks away from
the pin, loosening it and causing the
string to sag. When this cycle is reapted
time after time, the wood fiber surrounding
the pin are destroyed and lose their resilience.
this picture, this pinblock (without pins)
was removed from a piano during restoration.
With continuous swelling and shrinking,
the wood could no longer provide the snug
fit required to hold pins in place.
strings of your piano are responsible
for producing the musical sounds. With
exposure to high humidity levels over
long periods, strings become rusted and
the junction where rusted strings wrap
around rusted pins, rusted corrosion forms
a hardened bond between the two. Then,
during a tuning, when your piano technician
turns the pins to stretch the strings,
the inflexible rusted string snap at this