Changes In Humidity
Changes in humidity are the main cause of changes in piano tuning. When all the wooden parts like the soundboard, pin block and bridge are in a moist environment, the wood cells will absorb the moisture and swell up, which causes expansion and this pulls the strings tighter, which forces the piano to go sharp. On the other hand, if the piano is moved to a drier environment, the result is shrinking of the wood. The strings will lose their tension, and go flat, and wood might also crack. Opening of splits may occur and buzzes may be heard when the piano is played. It may also lead to enlargement of the wholes for the tuning pins in the tuning block, also called a wrest plank, which will cause loose tuning pins making piano tuning unstable, or even impossible. Each and every seasonal change, wet or dry, alters a piano’s tuning.
Changes In Temperature
The effect of changes in temperature is quite related to humidity. When the steel strings heat up, they slack, lose tension and go flat. When the steel strings get cold, they tighten, gain tension and the piano goes sharp. This happens every winter and summer, day and night as temperature changes, making piano tuning unstable.
Piano moving can also get a piano out of tune. The delicate position of the tuning pins in the pin block and the strings over the bridge pins is quite sensitive. Any time a piano is tilted or handled, there can be a shift in these positions.
Excessively Hard Playing
Excessively hard playing may cause a piano to go out of tune when the force of the hammer is strong enough to stretch the speaking length of the string enough to pull it over the friction points.
Aged Or Worn Materials
Materials can become aged or worn. Those related to tuning stability are generally wood, while some metal parts can give as well. The pin block can become split, or the tuning pins can become loose in their holes from repeated tunings or wood shrinkage. The bridges can split, typically along the line of the bridge pins. As the strings are tightened during tuning, the pins then move and do not keep the piano wire in place. Sometimes V-bars, agraffes, and hitch pins can bend or move as well.
Abuse Of The Piano
Abuse of the piano can also be a cause of a piano’s going out of tune. Avoid the abuse of a piano and there will be more stable piano tunings.