Allied Piano: Piano: Life Safer System: Damage Due to Humidity

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Piano Life Saver Systems
Damage Due to Humidity

The soundboard 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.

Bridge and Soundboard Damage

String/Soundboard Cross Section Moist Conditions

Moist Conditions
As 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 extreme treble strings.

Dry Conditions
When the soundboard shrinks and fattens, the tension of strings over the bride becomes inadequate. The pitch of the mid-range and treble strings is now flat.

Cracked soundboard Cracked Soundboard
Over time, constant changes in humidity levels, with the corresponding shrinking and swelling of the soundboard, will damage the integrity of the soundboard. Initially, you will see this damage in the form of a crack in the soundboard.

Pinblock Damage

Pinblock Cross Section Moisture Damage

Moist Conditions
The 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 the pin.

Pinblock Cross Section Dry Conditions Damage

Dry Conditions
In dry periods, the wood shrinks away from the in, loosening it and causing the string to sag. When this cycle is repeated time after time, the wood fibers surrounding the pin are destroyed and lose their resilience.

Damaged Pinblock
In the picture to the right, 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.

String Damage

Rusted Strings
The strings of your piano are responsible for producing the musical sounds. With exposure to high humidity levels over long periods, strings become rusted and corroded.

Rusted Pins
At the junction where rusted strings wrap around rusted pins, rust 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 snaps at this joint.