why does my piano go out of tune?

This question comes up a great deal in my business and so I have written the following article to address this concern and its importance to a healthy instrument.

The piano is constructed out of wood and metal, both elements being affected by temperature and humidity. Unfortunately, most piano owners do not implement preventative measures in these areas but, more often, contact a technician when a problem becomes apparent to the owner. In some cases the problem can be remedied with a considerable degree of cost but in most cases it is too late if the problem is so obvious and these problems only multiply over time if not remedied. It is sometimes difficult for a piano owner to invest in preventative measures when this, seemingly indestructible, instrument is in perfect working order. The best fix is prevention.

A few words about wood...

Wood is the main material used in building a piano. The frame, the case, the keys, the soundboard, the tuning pin block and most of the moveable parts contained in the action are all made of wood. Because the fibres in wood are porous, they absorb and release moisture through the humidity of the environment in which they exist. When the environment becomes dry, the moisture slowly evaporates from the fibres and will continue to do so until more moisture is introduced.

If this dry environment continues, the moisture content in the wood diminishes as well and the fibres begin to separate, eventually leading to a small crack or split in the wood. This is especially true with laminated segments. If more moisture is introduced, the crack may swell, temporarily pushing the fibres back together, however if the moisture content is significantly lowered again, the possibility of the, already existing, hairline fracture becoming larger increases.

When this humidity fluctuation is applied to the soundboard, not only do cracks appear but the consistent shrinking and expanding wood, affects the down-bearing pressure of the bridge which holds the strings across the soundboard. This effectively changes the tension, and thus the tuning, of the strings. If the strings remain out of tune for an extended period, the wood becomes somewhat "acclimatised" to the out of tune tension and returning it to it's original concert pitch becomes increasingly challenging with time.

If severe humidity fluctuation is continuously present, this same principal can cause fractures and larger cracks in the piece of laminated wood that houses the tuning pins of the piano. This is called the Pinblock. The pins are hammered very tightly into pre-drilled holes in the Pinblock, allowing them to withstand the torque of many tons (close to 20) of tension between the Tuning Pins and the Hitch Pins (where the strings are attached at the other end). Should a crack develop around one or more of these very precise holes, the pin will become loose and slip, as a result of the torque affecting it. This will cause the string to relax and produce a different vibration than it is intended to, thereby putting it out of tune with the rest of the instrument. In most pianos (especially uprights), the Pinblock is actually attached to the frame of the piano so if cracks develop, making the instrument un-tunable, the cost of repair or replacement of it will, most likely, far outweigh the value of the piano. It is effectively too cost-prohibitive to make this kind of repair on an upright piano, however with most Grand pianos, replacement is possible, albeit expensive.

Humidity fluctuation has considerable impact on, not only the tuning of your piano but the general health and value as well. Maintaining the moisture content in the wood of the piano at 42% is achievable through the use of a Dampp-Chaser Climate Control System.

A few words about metal...

The other material that a piano is made from is metal. Metal is affected by both temperature and humidity. When metal is warmer, it expands. As it cools it contracts so temperature fluctuations can affect the various properties of any metal part in the piano. Also, most metals, especially iron or steel (unless stainless), will respond to high humidity by corroding and producing rust. This becomes another concern with environmental humidity.

The Plate or, sometimes referred to as, the Harp is usually made of cast iron, in order to withstand the 20 odd tons of tension applied by the strings it houses. Although almost imperceptible changes from expansion and contraction of the Plate can affect the tuning, there is a greater effect on the strings that are made of steel, as they are less dense and respond to temperature fluctuations more quickly. As they warm up and expand, they lose tension, thereby reducing their vibrations and flattening the pitch of the strings. As they cool down, they contract, tightening the strings to produce a higher pitch. Because all of the strings are not the same gauge, they will contract and expand at different rates, putting the relative tuning out.

There are even recent developments in automatic tuning that use temperature fluctuation, controlled by a computer chip, to automatically maintain the piano's tuning. This technology is still in its infancy but is very interesting.

So the crux of this little article is to highlight that your piano goes out of tune because of environmental conditions and fluctuations as well as how much it is played. A regular, at least annual, visit from your piano technician will not only provide you with your "ounce of prevention", protecting your instrument and investment but will help develop your ear to hear music that is in good tune.

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This question comes up a great deal in my business and so I have written the following article to address this concern and its importance in maintaining a healthy instrument.
The piano is constructed out of wood and metal, both elements being affected by temperature and humidity. Unfortunately, most piano owners do not implement preventative measures in these areas but, more often, contact a technician when a problem becomes apparent to the owner. In some cases the problem can be remedied with a considerable degree of cost but in most cases it is too late if the problem is so obvious and these problems only multiply over time if not remedied. It is sometimes difficult for a piano owner to invest in preventative measures when this, seemingly indestructible, instrument is in perfect working order. The best fix is prevention.
A few words about wood ...
Wood is the main material used in building a piano. The frame, the case, the keys, the soundboard, the tuning pin block and most of the moveable parts contained in the action are all made of wood. Because the fibres in wood are porous, they absorb and release moisture through the humidity of the environment in which they exist. When the environment becomes dry, the moisture slowly evaporates from the fibres and will continue to do so until more moisture is introduced.
If this dry environment continues, the moisture content in the wood diminishes as well and the fibres begin to separate, eventually leading to a small crack or split in the wood. This is especially true with laminated segments. If more moisture is introduced, the crack may swell, temporarily pushing the fibres back together, however if the moisture content is significantly lowered again, the possibility that the, already existing, hairline fracture becoming larger increases.
When this humidity fluctuation is applied to the soundboard, not only do cracks appear but the consistent shrinking and expanding wood, affects the down-bearing pressure of the bridge which holds the strings across the soundboard. This effectively changes the tension, and thus the tuning, of the strings. If the strings remain out of tune for an extended period, the wood becomes somewhat "acclimatised" to the out of tune tension and returning it to it's original concert pitch becomes increasingly challenging with time.
If severe humidity fluctuation is continuously present, this same principal can cause fractures and larger cracks in the piece of laminated wood that houses the tuning pins of the piano. This is called the Pinblock. The pins are hammered very tightly into pre-drilled holes in the Pinblock, allowing them to withstand the torque of many tons (close to 20) of tension between the Tuning Pins and the Hitch Pins (where the strings are attached at the other end). Should a crack develop around one or more of these very precise holes, the pin will become loose and slip, as a result of the torque affecting it. This will cause the string to relax and produce a different vibration than it is intended to, thereby putting it out of tune with the rest of the instrument. In most pianos (especially uprights), the Pinblock is actually attached to the frame of the piano so if cracks develop, making the instrument un-tunable, the cost of repair or replacement of it will, most likely, far outweigh the value of the piano. It is effectively too cost-prohibitive to make this kind of repair on an upright piano, however with most Grand pianos, replacement is possible, albeit expensive.
Humidity fluctuation has considerable impact on, not only the tuning of your piano but the general health and value as well. Maintaining the moisture content in the wood of the piano at 42% is achievable through the use of a Dampp-Chaser Climate Control System.
A few words about metal ...

The other material that a piano is made from is metal. Metal is affected by both temperature and humidity. When metal is warmer, it expands. As it cools it contracts so temperature fluctuations can affect the various properties of any metal part in the piano. Also, most metals, especially iron or steel (unless stainless), will respond to high humidity by corroding and producing rust. This becomes another concern with environmental humidity.
The Plate or, sometimes referred to as, the Harp is usually made of cast iron, in order to withstand the 20 odd tons of tension applied by the strings it houses. Although almost imperceptible changes from expansion and contraction of the Plate can affect the tuning, there is a greater effect on the strings that are made of steel, as they are less dense and respond to temperature fluctuations more quickly. As they warm up and expand, they lose tension, thereby reducing their vibrations and flattening the pitch of the strings. As they cool down, they contract, tightening the strings to produce a higher pitch. Because all of the strings are not the same gauge, they will contract and expand at different rates, putting the relative tuning out.
There are even recent developments in automatic tuning that use temperature fluctuation, controlled by a computer chip, to automatically maintain the piano's tuning. This technology is still in its infancy but is very interesting.

The crux of this little article is to highlight that your piano goes out of tune because of environmental conditions and fluctuations as well as how much it is played. A regular, at least annual, visit from your piano technician will not only provide you with your "ounce of prevention" but will help develop your ear to hear music that is in good tune.
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