by Edward E. Swenson
All musical instruments require maintenance in order to assure optimum playing efficiency. Most wind and string players are able to tune and maintain their own instruments. Because the pianist is compelled to rely on a professional technician for tuning, voicing and repairs, the first and most important aspect of piano maintenance is to obtain the services of an experienced, reliable piano technician.
Temperature and humidity control are also critical elements in maintaining a valuable instrument. Central heating, without some kind of humidity control, poses a great danger for musical instruments made of wood. The worst possible environment for a piano is one with radical swings in humidity and temperature. In regions with hot, humid summers, and dry, cold winters, special attention must be given to humidifying in the winter and dehumidifying in the summer. Wood is hygroscopic and it expands and contracts across the grain with changes in humidity. The pitch of the strings depends to a certain extent on the amount of humidity present in the soundboard, which expands and contracts with changes in heat and relative humidity. If the environment is too dry, the soundboard will shrink beyond the dryness level at which the instrument was manufactured, causing cracks in the wood and even failure of glue joints. Extreme dryness can cause complete failure of the soundboard and pinblock. The loss of natural moisture in the soundboard also causes the pitch to go flat. In the winter, care must be taken to maintain a humidity of not less than 50% and a room temperature of not more than 65 degrees Fahrenheit. Conversely, too much humidity causes the soundboard to swell and bow upward, often causing pressure ridges in the soft, crushed fibres of the wood, increasing the tension of the strings and causing the instrument to go sharp. Too much moisture can ruin a piano, as it causes the wood in the keys and soundboard to swell, resulting in sticking keys, loose ivory, and sluggish response in the mechanism. Excessive moisture may also cause the strings, tuning pins and other metal parts to rust.
The lid of the piano should be completely closed when the instrument is not in use, in order to prevent the accumulation of dust and foreign objects in the action and on the soundboard. For instruments with ivory keys, however, the keyboard cover or fallboard should be kept open periodically, as ivory will turn yellow if it is not exposed to natural light. Care should be taken not to drop pencils, paper clips and other foreign objects, which can cause noise and damage, into the piano. Foreign objects on the strings and soundboard will produce irritating vibrations. Never put objects on top of the piano as they also can cause noises and vibrations. Sometimes other objects in the room, even window panes, can cause sympathtic vibrations with the piano tone. Vases, flower pots, beverage glasses or any vessel containing liquid, should never be placed on the piano.
No attempt should be made by the owner, without special instructions, to remove the action from the piano. To avoid personal injury and possible damage to the instrument, piano moving should only be entrusted to experienced piano movers who are fully insured for liability. Moths were very destructive to the felt in pianos made before World War II, but most modern instruments are made with mothproof felt.
Location: Finding an ideal location for a piano is often difficult. In the order of importance, the location should help preserve the instrument, be acoustically satisfactory, and aesthetically pleasing. Ideally, a piano should be placed on an inside wall, away from the direct rays of the sun. Moreover, it should not be placed next to heaters, stoves, air conditioners, or near heat ducts or cold air returns. Drafty locations next to open windows or doors should also be avoided. Instruments which are placed directly beneath water pipes or emergency sprinkler systems, should be protected from possible water damage with a waterproof cover. Finding the best location for a piano also includes acoustical considerations; usually a piano sounds best in a room without thick wall-to-wall carpeting or heavy, sound-absorbing draperies.
Tuning, Regulating and Voicing: The frequency of tuning depends in part on the severity of the climate, the age and condition of the piano, and the extent to which it is used. In any case, pianos should be tuned at least twice a year to keep the pitch level from sagging below A=440. New instruments should be tuned three or four times a year during each of the first two years, because the new strings will continue to stretch during that period. For instruments in home use, two or three tunings a year are usually adequate to keep a piano at concert pitch. An experienced piano tuner will thump the keys vigorously during tuning in order to encourage the strings to stretch and stabilize across their entire length. If piano tuning is neglected, the pitch of the piano will gradually go flat, often to the point where the tuner cannot raise it successfully in one tuning. Even after raising pitch, a neglected piano will not stay in tune as well as an instrument which is regularly maintained. Concert instruments are tuned before every concert, even if there are two on the same day, as the slightest inaccuracy in tuning cannot be tolerated in a concert.
Tuning a piano is not enough to ensure complete maintenance. Periodically the action and pedals should be regulated. The more an instrument is used, the more frequently it will require both tuning and regulation. Pianos which are in constant use, such as those in conservatory practice rooms and the studios of teachers and professional musicians, require much more frequent maintenance than instruments which are only used occasionally. In time the hammer felt will become grooved and flattened by the steel strings, necessitating reshaping, voicing and eventual replacement of the hammers. Reshaping hammers by sanding is a possible, but imperfect, solution to hammer wear as it also reduces the weight of the hammers and changes the blow distance between the striking point of the hammer and the string.
Voicing, or tone regulating, piano hammers should only be attempted by an experienced specialist. To regulate tone quality, the voicer first makes certain that the action is in perfect regulation and that the hammers have a proper acoustical shape. The hammers are also checked to ensure that they are striking all the strings of the unison squarely and simultaneously. Finally the density of the hammer felt is regulated by needling the shoulders of the hammers so that they produce an even, homogenous tone quality throughout the scale. Voicing should only be entrusted to a seasoned professional, as it requires a thorough knowledge of the piano mechanism, a sensitive musical ear, and years of experience.
Most pianos are not regulated as often as they should be. A competent piano technician must check action and pedal function after each tuning and make recommendations for regulation and repairs. The piano action will function after a fashion, even if it is very badly out of regulation, but the piano will not provide satisfactory results and may even hinder the progress of an unsuspecting student.
Cleaning: Periodically, the piano technician should clean the action, keys, soundboard and keyframe. Only the slightest amount of moisture should be used on ivory keys because dampness can penetrate the ivory and soften the glue which bonds it to the key.
Piano cases were finished with a variety of materials during different
historical periods. Alcohol-soluble spirit varnishes were used on early
instruments. Oil varnish was used for many instruments made after the mid-nineteenth
century, and both lacquer and polyester finishes are currently in use.
No single cleaning technique can be used for all of them. To clean a piano
case it is best to remove dust with a feather duster. A bit of moisture
from the breath, used in conjunction with a soft leather chamois skin can
be used to remove stubborn smudges, although it is usually best to consult
the manufacturer's instructions for maintaining the finish.