A piano should be tuned 6-12 monthly. Instruments used for concerts ideally require to be tuned on the day of performance.
Reasons For Tuning Pianos
1-Maintenance of pitch. At the standard pitch of A440 Hz, an average of 230 strings exert around 1,000kg of down-bearing on the bridge, which is glued to the piano soundboard*. Constant temperature and humidity fluctuations mean that even a piano that is not played looses its tuning, and pitch. The ideal climactic conditions for a piano, are a steady 18°-21° C (65°-70° F), at 42% relative humidity.
2-Maintenance of Touch. Pianos comprise of some 5000 parts, including felts, centre pins, springs, tapes, bushings, leathers, screws and washers. Over the years, these parts wear and bed in, causing the need for adjustments, regulating or replacement. New pianos in particular require this after a few years, as new key baizes and felts ‘bed in’.
3-Voicing. This relates to the amount of compression on the hammer felts, which affects the ‘voice‘ or ‘tone‘ of the piano. In a new piano, voicing is carried out before the it finally leaves the factory. Over the years, voicing can be done periodically, after a fine tune, to improve the overall sound of the instrument. Obviously, once piano felts have reached a certain wear, or age, the hammer-heads require re-felting, or to be replaced completely.
An average basic tuning takes around an hour. If the piano has not been serviced for many years, this can some times take longer. Also, an instrument that is significantly flat or sharp of standard pitch A440 Hz, requires to be raised/lowered, which normally takes extra time.
Great care must be taken with older pianos, which are mostly French-polished. Only a soft cloth should be used for these. Never use a spray polish. Shellac, what French-polish is made from, is soluble in alcohol. Modern pianos mostly have a polyester or satin lacquer finish. This only requires cleaning with a soft dry or very slightly damp cloth, and be left to dry naturally.
The best way is with a soft slightly damp cloth, rinsed in mild soapy water. There are also some specialist cleaners on the market. Discolouration on white keys is common, and is mostly irreversible. Also, be aware that even in the late eighteenth century, materials other than ivory were used to make white piano keys, and darkened pear wood was sometimes used for black keys. Today, plastic or a cellulose mix are almost exclusively used for all keys. However, because of the ban on ivory, some piano makers now using animal shin bone.
Upright pianos weigh approximately 136-227kg, or 300-500lb, and grand pianos around 240-490kg, or 530-1080lb, so ideally, a professional removal company, with past experience in moving pianos should be used. The cast iron frame makes up most of this weight and gives the instrument good structural strength. The string tension on the frame of a modern grand can exceed 20 tonnes! However, cast iron is vulnerable to cracks if it is dropped in a move.