How Does Humidity Affect My Piano?

Topic Series Notes: Piano Environment

A good understanding of how humidity relates to the health of your piano has the potential of adding years of life to your piano. I believe every piano owner would benefit from reading these short articles.

Humidity Swings And Piano Parts

Everything in a piano is either made of wood or depends on wooden parts to function. Wet humid conditions swell and warps wooden parts and dry parched conditions shrinks and cracks wooden piano parts.

While high humidity badly affects a piano and low humidity badly affects a piano, even worse is swinging back and forth, which is what we have in Kansas City ~ hot humid summers and cold dry winters.

Dryness causes wood to crack, which is the most serious damage, and many times those cracks would never develop, without first going through a period of damp humid conditions.

Soundboard Pressure Ridges

Let’s take the soundboard for example:

The soundboard already has a great deal of pressure exerted on it and wet humid conditions cause it to swell, pushing the wood grain with great force the soundboard sometimes develops a “pressure ridge”. On grand pianos, you can see these pressure ridges if you lower your eye-sight to just above level with the soundboard ~ to the point where the light glares off the soundboard. Once you spot a “pressure ridge” you can run your finger across the ridge and feel it under your finger.

At this point the pressure ridge is not considered a crack and no piano manufacturer will warranty a “pressure ridge”, yet if the piano goes through a period of dryness, this is where the crack will most likely develop. “Pressure ridges” can be seen on many pianos still sitting on the dealer’s showroom floor. This is one more, of the many reasons why you should never, never, never buy a piano without having a professional piano tuner examine the piano before you buy.

Soundboard cracks usually do not cause much of a problem to the tone and overall sound of your piano unless the soundboard ribs loosen and begin to buzz and rattle. Unless there is a rattle or buzz the soundboard will still perform. (For more information on why soundboard cracks do little to harm piano tone – see this Steinway technical.)

Humidity Swings And The Piano Pinblock

Piano Pinblock

Piano Pinblock

A more serious problem that may develop as a result of “humidity swings” is pin-block damage. The pinblock is what holds the tuning pins. The quality and condition of the pinblock determines the tightness of tuning pins and is one of the most important factors in tuning stability. For many manufacturers, including Steinway, the minimum specification allowed for tuning pin tightness, to pass inspection and exit the factory is only 50 inch pounds. While technicians, like myself, would like all new pianos to measure 75 to 85 inch pounds many leaves the factory with much less.

What This Means For The Piano Owner?

A piano is still tunable at 50 to 60 inch pounds, but once the pinblock loosens to the point the tightness of the tuning pins only measures 25 to 30 inch pounds, we generally consider that piano no longer a tunable piano. After a piano has gone through a few seasonal changes, it is not uncommon for the pinblock to loosen five to ten inch pounds in the first five years of service. To avoid getting stuck with one of those 50 inch pound pianos, never, never, never buy a piano without a professional piano tuner appraising the quality of the piano before you buy.



Note: About the above “Piano Bridge” pictures ~ The piano soundboard is designed to have a crown.  The image for “Dry Conditions” shows a flat soundboard which is not accurate.  In dry conditions I am sure the soundboard flattens more than it should but not completely flat. The image that shows “Moist Conditions” is demonstrating too much crown ~ which is what happens in moist conditions.

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Piano Voicing

Piano Voice ~ Adjusting Piano Tone

Voicing is the process of regulating and improving piano tone. As pianos age the hammer felt becomes harder and worn, and the strings stretch and ride up on the bridge pins. The strings become wavy, distorted and produce less resonance and the hammers produce brassy overly bright sound.

When a piano is in tune, if you play a mellow soft note with a bright brassy loud note it sounds inharmonic. Many times I have followed piano tuners who have done a decent job tuning the customers piano, however the customer was complaining. After examining the piano, it became apparent the problem was poor voicing and not poor tuning. A piano that is in poor voice will sound oddly inharmonic even with good tuning.

Technically, any adjustment that alters piano tone is voicing, such as brushing the hammers, stretching, straightening and seating the strings or needling the hammers. When the topic of piano voicing is discussed, usually the conversation is about adjusting the hammers. If you Google “Piano Voicing” you will find many results and tuners offering hammer needling as voicing. However if you Google “Piano String Voicing” the only page you will probably find is the one you’re currently reading. I am aware of only a handful of piano technicians ~ the best in the United States ~ who incorporate string voicing into their service.

I have known of customers who have purchased new pianos or purchase expensive modifications to their pianos when a good string voicing along with hammer voicing would have accomplished the same result and they could have saved thousands of dollars. I include string adjustment in my piano voicing routine because it has a wonderful affect on the resonance and clarity of piano tone.

String voicing restores the resonance and removes most of the waviness and distortion, and hammer voicing evens out the tone. It is truly amazing how much better a piano sounds after it has been voiced.

Piano voicing involves:

Restoring the resonance and clean tone to piano strings

( Can be preformed on vertical pianos but usually on grands )
( Must be preformed before tuning )

  • Stretching, straightening and seating the strings on the bridges
  • Leveling the strings around the agraffes and capo
Restoring the evenness of piano tone by adjusting the hammers

( Preformed on either grands or verticals )
( Must be preformed after tuning )

  • Softening overly hard hammers
  • Brushing hammers
  • Needling to remove inconsistent and uneven tones

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