Thomson Lawrie

Piano Tuner/Technician

Since 1979

Over 40 years experience with Yamaha, Kawai, Steinway, Mason & Hamlin, Petrof, Samick, Young Chang, Heintzman, Mason & Risch and many more.....

Pianos & Humidity Control

soundboard crack People often ask what they can do to look after their piano. I always tell them the most important thing is to keep the humidty level. The second most important is to keep the humidty level and the third...? You guessed it. Nothing is more important to the maintenance of a piano than controlling humidity. The picyure to the left is of a crack in the soundboard of a fairly recent vintage grand piano. There were no cracks in the soundboard when I tuned this piano in the pervious spring but when I returned in January there were five cracks, two of which that ran the whole length of the board. What could cause a soundboard to crack like that? Humidity, or in this case the lack there of. The picture below shows that the room that this piano was in was at 15% humidity! That is very unusual but it isn't uncommon for some homes to drop to the low 20's in the dead of winter and humidty in the low 20's can cause some real damage. It's so important that most tuners will carry a hygrometer with them among their tools to diagnose humidity related problems.

The fact is, there isn’t a piano made that will stay in tune if it is exposed to dramatic swings in humidity. The soundboard, bridges, back posts and pinblock of every piano are made of wood and those wood components swell with rising summer humidity and shrink with winter dryness. Unfortunately, because the strings are all different lengths, the pitch does not rise evenly. The reverse happens when the heat comes on in the fall and the inside air starts to dry out. The shrinking wood will allow the tension to come off the strings and the pitch drops accordingly.

Piano technicians know from experience, that pianos in concert halls, which are tuned throughout the year will always follow a predictable pattern. When the season starts in the early fall, the piano will be above pitch from the summer humidity. Throughout the fall the pitch of the piano will drop a little each time between tunings. This goes on until the spring when the humidity starts to rise. From that point on, each time they return they will find the piano has crept up in pitch and has to be brought back down to concert pitch. This continues until the fall and then the whole cycle starts over again.

Uncontrolled humidity swings can do more harm to a piano than just affecting the tuning. High summer humidity and extreme winter dryness can cause cracks in the soundboard and bridges. The cracks will appear in the winter when the wood shrinks but the high summer humidity may have been the cause, as the wood crushed together when it expanded only to separate when it dried out later. Extremes in humidity can also lead to sluggish or sticking action components. I always get the most calls to fix sticking keys in the dead of winter and during a summer heat wave.

15% humidity reading

What does this mean for your piano?

You can prevent damage from humidity swings by...

  1. never placing a piano on top of a heating vent.
  2. If you have a grand piano close to a forced air vent, place a baffle on it to direct the flow away from it. This will protect it from having the heat collect under the soundboard.
  3. Don’t place your piano in a south facing picture window. The sun is lower in the sky during the winter and it will bake the piano every afternoon in what is already the driest time of the year.
  4. Have a good humidifier installed on your furnace.
  5. Use your air conditioner throughout the summer. It will draw a huge amount of moisture out of the air and it will prevent the piano from absorbing it.
  6. Have a humidity control system installed in your piano. The Dampp-Chaser® "Piano Life Saver System" is designed to control a piano's internal humidity levels and I recommend them for any piano that is in an environment where humidity is not well controlled. These systems are particularily useful in public building such as Churches, Retirement homes, Schools and Universties where humidity is harder to control than the average home setting. Pianos with the Piano Life Saver Systems require less tuning than pianos that are left unprotected, whether that is is a public building or an in home setting. Generally speaking, your home will have much better humidity control than most institutional buildings, but even there it isn't unusual to see humidity swing from 80's in summer to low 20's in winter. When humidity swings that far the tuning will go with it. If you have recently purchased a new piano and would like to protect it or if you are just tired of having your piano go out so often, it might be worth concidering a piano humidity system for your piano.

Upright System

The Piano Life Saver humidity control system works silently raising humidity in dry conditions and lowering humidity as humidty rises above ideal conditions. The system is installed inside upright pianos and under the soundboard of a grand piano. Call or text 905-945-9455 or email for an installation price quote.

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Thomson Lawrie


Jordan Station, ON