Sudden or Excessive Changes
Rapid changes in heat and cold, and excessive changes in moisture and dryness, cause the various parts to shrink or swell - and such changes affect the tonal quality as well as the tuning and adjustment of your piano. Changes in atmospheric humidity will in time affect the moisture content of piano parts made of wood, even those parts that are carefully coated with lacquer. The result is a continual swelling and shrinking, expansion and contraction, of all wood parts in a piano.
Excessive humidity or dampness is very detrimental to pianos, causing rusting, sluggish actions, bursting of case parts, etc. This is especially harmful when followed by the excessive dryness of artificial heat in winter, and precautions should be taken in homes where there is extreme heat. Avoid excessive changes in humidity as much as possible.
There are many devices, both electrical and mechanical, designed either to increase or reduce the humidity in a home. Consult your piano dealer, piano tuner-technician or "Piano World" for advice on this subject.
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Low humidity opens the joints in floors, makes the furniture become unglued, and sometimes cracks the piano soundboard. This does not necessarily harm the tone of the piano. However, with the new finishes, new glues, and continual perfecting of manufacturing processes, pianos have become surprisingly resistant to these atmospheric changes. Do not place your piano over a heat register or against a radiator or window. Also, it is better to place it against an inside rather than an exterior wall, unless the wall is fairly well insulated. If you take care of your piano, it will give long and satisfactory service.
When in doubt consult the dealer from whom you bought the instrument, your piano tuner-technician, or write the manufacturer.