Article:     ►  “How Often and When Should I Have My Piano Tuned”  -   Larry Fine 

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    “When to tune your piano obviously depends on your local climate and how responsive your piano is to hu­midity changes. But, in general, you should avoid times of rapid humidity change and seek times when the humidity will be stable for a reasonable length of time. Turning the heat on in the house in the fall and winter, and then off again in the spring, both cause major indoor humidity changes, and in each case it may take several months before the piano soundboard fully stabilizes again at the new humidity level.

 “In Boston, the tuning cycle goes something like this for most pianos... A piano tuned in April or May when the heat is turned off in the house will prob­ably be out of tune by late June. If it is tuned in late June or July, it may well hold its tune until October or later, depending on when the heat is turned on for the winter (although sometimes extreme humidity in August will do it in). If you have the piano tuned right after the heat is turned on, say in October or Novem­ber, the piano will almost certainly be out of tune by Christmas. But if you wait until after the holidays (and of course, everyone wants it tuned for the holidays), it will probably hold pretty well until April or even May. In my experience, most accusations of tuner incompetence occur in November or December, and then to a lesser degree in June, and are caused not by the tuner at all, but by poor timing of the tuning with the seasonal changes. 

     “If you have the piano tuned four or more times a year, you don't have to worry too much about the "right" time to tune it. Any seasonal tuning changes will be corrected soon enough. It's those who tune their pianos twice a year who have a problem. For these people, there will be at least two times per year when the piano is noticeably out of tune but when it will not yet be the right time to tune it. If you are in this group, you will have to decide then whether to go ahead and have it tuned-knowing it may go out of tune within a month or so-or to suffer until the "right" time. At those times of year, I try to inform customers who call for a tuning about the consequences of having the piano tuned then, and let them decide how badly they want it done. 

     “There is an additional problem for the twice-a-year people. The times of rapid humidity change—spring and fall—are also the times of most moderate indoor humidity levels, while the times of stable humidity summer and winter-are the times of most extreme humidity levels... the pitch of the middle range of the piano follows the humidity changes and is therefore most sharp and flat at the "recommended" tuning times. Pianos tuned at these times may have to
undergo large pitch changes to bring them back to standard pitch.     [ ...scroll up to (2) ]

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    "As any tuner can tell you, large pitch changes are the bane of stable tuning, as structural forces within the piano tend to make a piano tuning creep back in the direction from which it was moved. Pianos showing large seasonal pitch variations may require extra tuning work, at greater expense, and may not stay in tune as well.  

     “Thus, ironically, the tuning times recommended in response to climatic factors are the least recommended times in relation to structural stability, and vice versa. Unfortunately, there is no solution to this problem except to have the piano tuned more often. 

     “If you tune the piano only once a year, you should do it at the same time each year so the tuner will not have to make much pitch adjustment. Some pianos actually go back into almost perfect tune each year around the anniversary of their tuning (but don't count on this happening).   How often you have the piano tuned will depend not only on the piano and the humidity inside your house, but also on your ear (how much out-of-tuneness you notice and can tolerate) and on your budget. Four times a year is ideal, but impractical for most folks. The "official line" is twice a year. Where the piano is rarely used, once a year may suffice, but less than that is not recommended. The average cost of a piano tuning is currently from seventy-five to one hundred twenty-five dollars, depending on where you live. The cost could be higher if a "double tuning" (a rough tuning followed by a fine tuning) is required to compensate for large seasonal variations in pitch, or if for some other reason the piano was not at standard pitch. In some areas of the country, a double tuning is required almost every time a piano is tuned. Also, as mentioned in Chapter 3, new pianos (or pianos that have been restrung) may need to be tuned more frequently the first year or so as the new strings continue to stretch. 

     “You may legitimately ask how important it is to have a piano tuned; that is, will harm be done to the instrument if it isn't tuned? This is a subject piano technicians don't discuss much. When they do, they offer a variety of pseudoscientific explanations to convince their customers (or themselves) of the necessity for tuning. The truth, as I see it, is that in most cases no harm will be done to the piano. The harm is mostly to one's aesthetics-an out-of-tune piano can be painful to listen to. It can also be discouraging and distracting to a student. It may be impossible to play along with other instruments or with recordings, and the piano's tonal quality may be      [...scroll down to (3) ]

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impaired. In the extreme case where a piano is being tuned after, say, twenty years of neglect, raising the pitch of the piano back to standard pitch will entail a good deal of extra work and could result in some broken strings or split bridges, but I’m not convinced that these problems wouldn’t have occurred anyway, and possibly sooner, if the piano had been maintained. Raising the pitch of a piano can also alter the positions of the strings in relation to their bearing points, introducing tonal irregularities (false beats) and buzzing strings, but this can often be corrected, and in any case is not what I would call “harmful.”  

   “Suggestions that the piano will be structurally harmed if it is not precisely at standard pitch and in tune are, in my opinion, spurious. Having the piano serviced at regular intervals, however, may allow the technician to catch and correct small, non-tuning-related problems before they become big, expensive ones. 

Relative Humidity 

     “Relative humidity is a measurement, expressed as a percentage, of the amount of water vapor in the air compared to the maximum amount the air could possibly hold at a given temperature. The relative humidity of the outdoor air depends on the nature of the air mass-that is, how moist or dry it is-and on the temperature, because the ability of the air to hold moisture increases with increasing temperature. So if we take a "parcel" of air with a certain amount of moisture in it and we heat it up, the relative humidity will decrease, because the amount of moisture in the air will have decreased in comparison to the amount the air is now capable of holding. Alternatively, if we cool that air, again without adding or subtracting moisture, the relative humidity will increase, because the capacity of the air to hold moisture will have diminished.

   “The relative humidity of the outdoor air can be high or low from day to day, regardless of the season. The reason such a fuss is made about low winter humidity is that in climates      [...scroll up to (4) ] 
 

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that have cold winters, the indoor relative humidity is artificially lowered by heating the air with a furnace system without supplying any additional moisture. If, for example, the outdoor temperature is 32 degrees Fahrenheit and the outdoor humidity is 100 percent (an extreme example), by the time the air is heated to 68 degrees indoors, the indoor relative humidity will have dropped (theoretically) to only 28 percent (the actual amount may be a little higher due to human respiration, plants, and other factors). 

    “A continuous exchange of moisture goes on between the air and the wooden piano parts and other porous objects around the house, as the moisture level attempts to reach a state of equilibrium. Since the air is usually a much greater reservoir of moisture than the objects, it tends to dictate the terms of this interchange. When the relative humidity is low, the air sucks up moisture from the piano, causing the pitch to fall, tuning pins to loosen, and parts to rattle (not to mention causing plants to wither, furniture joints to loosen, skin to crack, and throats to get sore).

   "Piano manufacturers suggest that the ideal humidity level for pianos is about 40 to 50 percent, whereas studies show that for people, 50 to 60 percent is best. Actually, as far as pianos are concerned, the particular humidity level is not nearly as important as the change in humidity through the seasons. In most cases, a piano can be adjusted to exist quite well at any reasonable level of humidity as long as it doesn't change much. But when, as happens in most of North America, the indoor humidity goes from very high to very low and back again, year after year, the alternate expansion and contraction has the net effect of shrink-ing, cracking and warping even wood that has been well seasoned prior to manufacturing.  One of the most important parts of good piano maintenance is keeping the humidity as constant as possible....”

END of Excerpt from "The Piano Book" - Larry Fine