How Humidity Affects Your Piano
Have you noticed your piano sounding out of tune as the seasons change? Humidity is often the reason.
Here in Colorado, pianos tend to go sharp during the more humid months and flat during our dry winters.
Why Does This Happen?
A piano's soundboard is made of wood, which expands and contracts as humidity changes.
When humidity rises, the soundboard absorbs moisture and swells. This changes its natural curve, called the crown, and pushes the bridges against the strings, increasing their tension and raising their pitch.
When the air dries out, the opposite happens, and the pitch drops.
Why Doesn't the Whole Piano Change Equally?
Different sections of a piano respond to humidity changes differently.
The middle of the soundboard generally moves more than the outer edges, so the middle registers often change pitch more than the lowest bass and highest treble.
Most pianos also have a separate bridge for the bass strings. Because the bass and middle registers can shift by different amounts, chords and octaves that cross between these sections can sound particularly out of tune.
Can Humidity Damage a Piano?
Over time, repeated swelling and shrinking of the wood can cause problems beyond tuning.
The wood surrounding the tuning pins can become permanently compressed, reducing its grip on the pins and making it harder for the piano to hold a tuning.
Excessive dryness can also contribute to cracks in wooden components, while high humidity can cause sticking keys and sluggish action.
What Can You Do?
Keeping your piano's environment reasonably consistent is one of the best ways to protect it.
A simple digital hygrometer can help you monitor humidity. Around 40–45% relative humidity is a reasonable goal for many pianos, but avoiding large fluctuations is especially important.
Keep your piano away from heating vents, fireplaces, and other sources of rapid environmental changes.
Most home pianos benefit from tuning once or twice a year. Some require more frequent tuning because of their environment, condition, or how heavily they're used.
Regular tuning and a stable environment will help keep your piano sounding its best.
Dustin Adams Piano Service
Professional Piano Tuning & Repair
Littleton, Denver, and the Colorado Front Range
