In this section we will quickly discuss some of the more common piano warning signs that may indicate that the levels of humidity are not adequately being controlled to prevent instrument damage. We will also touch on a few of the more common problems than may develop.
It should to be mentioned, while looking over the list below, each problem mentioned may not always result from high or low humidity but may be a sign of other problems. You should always mention any problems when making an appointment for piano service, or directly to your tuner/technician during a visit. It is usually much cheaper to have the problems remedied sooner than later - in fact if the problem is minor a Parks & Sons tuner/technician may likely make the adjustments during a tuning visit for no extra charge.Some High Relative Humidity Signs:
One of the most common problem related to high relative humidity is sticking keys. We will usually see this more in the spring when home heating systems are turned off and windows are opened. The wood of the keys and their bushing felts quickly absorb the moisture in the air during this high humidity season. The resulting swelling causes the effected key(s) to rub against its fellow. The key sticks in the down position for a few seconds before returning to its normal position - or remains stuck in the down position until manually lifted. On the other hand the keys may be "stiffer" during play. While sticking keys can be a sign of action problems rather than high humidity, the humidity is the most common cause.
A sluggish action can make a piano quite unpleasant to play - the instrument simply does not respond very well. Beginners tend to blame their own abilities rather than realize the need to have the instrument serviced.
While age and wear can cause the action to develop sluggishness, high humidity can as well. In the cases of high humidity the felt bushings, on which the parts rotate around a brass pin, swell up with humidity and tighten against their pins. This of course causes much more friction, and can slow (or even stop) the response of action parts.
Rust can be a sign of not only exposure to high relative humidity but also uncontrolled temperatures. Since metals warm slower than the air, high humidity tends to cause condensation onto the metal parts (such as the plate, tuning pins, bridge pins, and strings). This then results in rusting of the metal.
Fallboards Stick or Jam
Another possible sign of high humidity effecting the piano is if the fallboard sticks or jams while being opened or closed (again this could be a sign of other service needs - especially if the fallboard has this problem year round).
Tuning Gone Sharp
A rise is relative humidity can also effect tunings. As the soundboard swells, its crown will increase. This increased crowning will create more downbearing on the strings, and so increase string tension. Of course an increase in string tension means the notes are now sharper (higher up the scale) than they had been tuned to. While the daily rise and fall of relative humidity contributes to a piano slowly falling out of tune, these sharp and prolonged increases can produce very noticeable effects. It should always be remembered that even the highest quality piano will be in need of at least one tuning per year to remain close to being in tune.
While the warning signs above can result from high relative humidity, there is the opposite problems - low relative humidity.
The problems that tend to show themselves in instance of low humidity will usually have their root causes from being exposed to both low and high. The repeated, unprotected exposure of the wood to these extremes cause the wood to swell and shrink both rapidly and excessively.Some examples of damage that may occur from this type of problem could be:
Quality soundboards are made from quarter sawn spruce boards which are glued to from a large single sheet of wood. Quarter sawn wood tends to have very little swelling and shrinking under normal conditions. If exposed to low and high extremes the soundboard may still crack, either along a seem or with the grain of the wood (it is not unusual to find multiple cracks when this occurs).
The good news for a piano owner is that cracks in the soundboard will usually cause no tone loss to the instrument itself. The damaged caused is usually quite repairable, and when caught early, not very expensive to have repaired.
The bad news is that these cracks will usually cross under ribs on the soundboard (ribs are wooden supports that help stabilize, strengthen, and crown a soundboard). When this happens it is common for a noticeable "buzz" to be heard when notes are played in the effected area. Yet another problem could be the cracks running beneath bridges and causing the glue joints to loosen. If left untreated both problems may grow worse until the piano is basically "unplayable" until repairs are made. It is better to solve the problem early.
This is probably the most talked about damage that a piano may suffer. Pinblocks are composed of sheets of a hardwood (such as rock maple) glued together at right angles.
With age it is not unusual for a few cracks to appear in the outer layer of these plys, which should have no effect of the instrument. On the other hand, with exposure to extremes of high and low humidity cracks may form that penetrate multiple layers and cross over the wholes in which the tuning pins are seated. These cracks cause the wood to lose its holding power on the pins. In such a case the piano will no longer hold a tuning.
While there may be "work arounds" that temporarily "fix" such a problem the only permanent solution is a pinblock replacement. The best remedy is to try to prevent it.
Joint failure is a common problem in areas of uncontrolled humidity, not only for pianos but all wooden furniture (leg joint separations, veneer loosening, lyre joint separations, etc.).
Joints are usually composed of at least two pieces of wood in which the grains are not running in the same direction (imagine a bench leg with its vertical grain joining by mortise and tenon to the frame with its grain running horizontally). Since wood swells and shrinks mostly across its grain, excessive high and low humidity can cause the glue joints to fail and separate.
Warping, Cupping, and Cracking
Yet another problem that can arise from excessive swelling and shrinking is known as compression shrinkage. Most of us have seen this at one time or another (cupped boards of wood floors and decks). This type of swelling can lead to warping, cracking, cupping, etc., of the wood.
Clicking Action Noises & Loose Action Parts
As wood and felts shrink from loss of moisture to the air, action flanges can become loose enough to cause parts to click against each other. Shrinking wood may cause screws to loosen.
Parks & Sons Piano Service always recommend making it a goal to controlling a piano's environment. We believe this is the best approach for both the piano and people - the instrument benefits (tunings last longer, parts wear less, etc.), while the people benefit from the healthier environment (less respiratory irritations, etc.).
If treating the environment around the instrument is not practical (i.e. a school environment in which the instrument may be required to be moved, or in a home in which the use of humidifiers and dehumidifiers is not desired), then Parks & Sons Piano Service recommends the use of an in-piano climate control system (you can read more on this type of system by in our Library).