By The Staff at Dampp-Chaser

Heating and Air Conditioning Limitations
Depending on an air conditioner or relying on a humidifier attached to your furnace to maintain a stable humidity doesn't meet the needs of your piano.

Air conditioners turn on and off to maintain a desirable temperature. When this temperature is achieved, the unit turns off, no matter what humidity level is attained.

Most furnace humidifiers have the same limitation: when the furnace has achieved the desired temperature it and the associated humidifier turn off, no matter what humidity level is attained.

Key Response
As 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 touch.

Bridge and Soundboard Damage
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.

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 treble section.

Dry conditions. When 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.

Soundboard damage. Over 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.

Pinblock Damage

The strings of your piano are held tight by the pins in the pinblock.

Moist conditions. As the pinblock absorbs moisture in periods of high humidity, it swells, crushing the wood fibers against the pin.

Dry conditions. In dry periods, the wood shrinks away from the pin, 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.

In this picture, the 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.

Rust Damage
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.

At the junction where rusted springs 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.