Pianos and Humidity

Piano Tuning Humidity New Jersey

Humidity changes can have a strong effect on pianos. All the wooden parts are susceptible to swelling and contracting due to humidity changes. As the relative humidity goes up, the soundboard expands which causes the pitch of the piano to drift sharp. Conversely, the pitch will begin to drop as the relatively humidity goes down. Due to the nature of the soundboard, the notes in the middle of the piano are more susceptible to humidity swings than the notes on the extreme ends. Therefore, as the humidity varies, the high treble and low bass will begin to sound either sharp or flat. Even as the humidity returns to normal, each individual string won't return to the exact tension and will be slightly out of tune. The greater the humidity swings, the more the tuning will drift.

As the moving parts take on extra moisture, they can swell up causing sticking keys or notes that don't play. Repeated cycles of swelling and contracting can cause loose flanges, loose pins, clicking keys, etc. These problems are easily addressed for the most part. However, it's always a good idea to try to keep the relative humidity as even as possible.

Piano Repair in NJ

Any place where wood and metal meet can cause problems with humidity swings. For instance, during periods of high humidity, wooden parts such as flanges will take on moisture and will try expand against a metal screw. Since the metal won't budge, the wood fibers begin to compress. When the humidity goes back down, the now compressed wood fibers shrink away from the screw and leaving a small gap between the wood and the screw. Repeated cycles of compression and release can cause loose flanges, which in turn can lead to many problems such as clicking notes, misaligned hammers, etc.

Too much moisture can cause the strings to rust. Here is a piano I recently serviced:

The strings have begun to rust into place. Notice that three strings have already been replaced (a single string goes up and loops back down) and the replaced string on the left has already begun to rust. There is also a string missing. This piano could use a complete restringing as well as a thorough cleaning!