How Does Humidity Affect My Piano?

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. High humidity badly affects a piano and low humidity badly affects a piano, and even worse is this 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

For example, let’s take the soundboard:

The soundboard already has a vast amount of pressure exerted on it; and wet, humid conditions cause it to swell, pushing the wood grain with enormous force the soundboard sometimes develops a “pressure ridge”. To view these pressure ridges on grand pianos, lower your eye-sight to just above the level with the soundboard ~ to the point where the light glares off the soundboard. Locate the “presure ridge” and run your finger across the ridge and feel it under your finger.

At this point, the pressure ridge is not considered a crack and a piano manufacturer will not guarantee 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 buying a piano WITHOUT having a trusted professional piano tuner inspect the piano before signing a purchasing contract, is never, never, never a good idea.

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.

Humidity Swings And The 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 significant 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 pianos leave the factory with only the minimum specification

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 extent the tightness of the tuning pins only measures 25 to 30 inch pounds, that piano is no longer considered 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 purchase.

Piano Pinblock	Dry Piano Pinblock Conditions	Moist Piano Pinblock Conditions
Rusted Piano Tuning Pins and Piano Strings	Piano Pinblock Damage (Tuning Pins Removed)	Rusted Piano String Damage
Piano Bridge ~ Dry Conditions	Piano Bridge ~ Moist Conditions	Cracked Piano Soundboard
Sluggish Piano Action Resulting From High Humidity	Sticking Piano Keys Caused From Too Much Moisture ~ Humidity

Note: Piano manufacturers design soundboards 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 entirely flat.