What happens to your piano after the deep cycling of temperature and humidity we have been experiencing? This winter (as if I have to remind you) was exceptional in the unremitting cold which lasted 30 – 45 days longer than normal. Time will tell if this summer will match the winter in its extremity. But with one leg of the deep cycle completed, I think it is important to take a moment and consider what this winter did to our pianos.
The wood and felt in our pianos has lost much of its moisture; here is how some of the wood and felt components have reacted to these dryer conditions.
While wood may shrink as it dries, counter intuitively, the many holes found in the keys may also shrink causing key bushings and key pins to bind. Also the keys may deform and begin to rub on their neighbors. As the wood dries, the bond between your key tops and key sticks may break. It is not unusual for key tops to begin to lift, making clicking noises when played, or even just come right off. As your keys change dimensions, your piano’s action regulation can become very erratic; your keys may no longer be level and your hammer line (properly known as the blow) can become quite uneven.
Felt and Glue in Hammers & Center pin bushings
As your hammers dry out, you may find the tone quality becoming more “tinny” and thin sounding. The hammers will lose some of their resiliency. A less resilient hammer will bounce off the strings instead of “pushing” off, thereby leaving the upper partials more active, giving a tinny sound. It is also not unusual for the glue joint between the hammer and the shank to fail as the wood in both the hammer and the shank shrinks.
The felt in your center pin bushings will wear much faster as it dries. The result can be the center pins becoming too loose and even beginning to walk out so you can see them on the sides of the hammer shanks. If the pins walk far enough they can completely disengage with one side of the hammer shank, and then your hammers will really wobble around, enough to actually hit neighboring strings.
The most obvious effect from the drying of your piano occurs in the soundboard. As it dries out, its crown will begin to collapse. With less upward pressure on the strings, the piano will not only go “out of tune” but the pitch will begin to drop precipitously. The first to go is the low tenor, in the area just above the bass/tenor break. If you play an octave such as A1 and A2 (the second and third A’s from the bottom) on a larger piano (or any other octave which crosses the break) and it sounds out of tune, the odds are very strong that it is the upper note which has moved, not the lower.
By the time the pitch drop extends a little past A4, (the A about middle-C) the entire treble will begin to go out of tune, sometimes in a very chaotic manner.
As the soundboard continues to dry, cracks, which were invisible in the summer, will begin to open up. The glue joints between the ribs and panel may also fail. In the most extreme cases the soundboard may actually come unglued from the rim.
The most damaging change occurs in the pinblock which is located under the harp. All summer the pinblock was been full of moisture and swollen; crushing the wood fibers against the steel tuning pins. Now, after the deep drying cycle, the pinblock has given up much of its moisture content and the tuning pins and the screws can become quite loose. If an actual crack develops in the pinblock, the piano will become un-tunable and will need a new pinblock.
This is just a short summary of what our pianos experienced after the extreme cycles we have recently gone through. Feel free to give me a call or drop me a note to discuss any unusual things going on with your piano.