Piano manufacturers and technicians recommend that a piano be tuned twice per year – especially in our region. This is particularly important for new pianos. There are only three reasons a good piano will go out of tune:
Strings stretch. Strings stretch throughout the life of the piano. The older the strings, the less flexible they become. When piano wire is new it has irregularities in its diameter. As it stretches, the diameter becomes more uniform, producing better tone because the overtones rings more precisely. Therefore, a new piano requires more tuning. Experts recommend four tunings the first year and twice a year thereafter. Not tuning a piano this often will not damage the piano, it will just delay the time until the piano reaches its tonal potential.
Soundboards move. Even good spruce soundboards have cellular matter between the grains. These areas take on humidity in the summer, causing the board to swell. Because the board is crowned, additional tension is forced on the strings causing them to go “sharp,” or up in pitch. Additionally, the increased tension may cause the tuning pins to slip or the string to sit on a new spot at the bridge pins. In the winter, when the humidity is reduced, the board shrinks, resulting in an out-of-tune piano. If you live in a tropical area that is always humid, or a desert that is always dry, your piano will be more stable with regard to its tuning. The tighter the grain of the soundboard, the less susceptible it will be to changes in humidity. Air conditioning and furnace humidifiers will help, but will not completely eliminate the effects of seasonal changes in humidity.
Tuning pins slip. If the wood holding the tuning pins (called the ‘pinblock’ or ‘wrestplank’) has dried out and constricted, the tuning pins will not be able to hold the proper tension on the string and the pitch will go flat shortly or immediately after tuning. This problem is only correctable by replacing the pinblock. Moving a piano with loose pins may cause it to go out of tune, but the problem wasn’t caused by moving. It was caused by the defect in the piano.
Any piano that can’t hold its tuning through a normal move should be avoided.