Symptoms
- The piano sounds sour again a few weeks after tuning
- It sounds better in one season and worse in another
- Certain notes or a whole section keep drifting
- Single notes slip flat even when the rest holds
Likely causes
Humidity swings
The soundboard swells in humid weather and shrinks in dry weather, pushing the pitch sharp and flat. This is the most common reason and it affects every piano.
A recent big pitch change
If the piano was far below pitch, raising it adds a lot of tension to the frame. The strings and wood need time, often a second tuning, before they settle.
Loose tuning pins
In older pianos the pinblock wood can lose its grip on the tuning pins, so individual strings slip back flat.
New strings or a new piano
New strings keep stretching for months, and new pianos need several tunings in the first year before they stabilize.
Heavy use
Hard playing every day, as in schools or studios, gradually shifts the tuning faster than light home use.
What you can safely check yourself
- 1Put a hygrometer next to the piano and keep relative humidity between 40% and 50% with a dehumidifier or humidifier as needed.
- 2Move the piano away from AC vents, windows, radiators and direct sun.
- 3Note which notes drift: a whole region suggests climate, a few single notes suggest loose pins.
- 4Track how long each tuning lasts and in which season, and share it with your technician.
- 5Keep the AC or heating at a steady setting instead of switching it hard on and off.
What not to do
- Never turn the tuning pins yourself with pliers or a wrench — you can bend pins or break strings.
- Don't pour 'pin tightening' liquids or CA glue into the pinblock without a technician's assessment.
- Don't skip tunings to 'save' the piano; long gaps make each tuning less stable.
Quick fixes vs. call a pro
You can usually handle it
- Measuring and controlling room humidity
- Relocating the piano away from vents and sun
- Logging which notes drift and when
- Keeping AC and heating steady
Call a technician
- Testing tuning pin torque
- Pitch raise plus follow-up fine tuning
- Installing a humidity control system inside the piano
- Pinblock treatment or oversize pins for slipping notes
What a technician will do
A technician checks the tuning pin torque while tuning and looks for notes that won't hold. If the piano was far off pitch, expect a pitch raise and a second tuning a few weeks later. For pianos that react strongly to climate, an in-piano humidity control system can be installed in about an hour or two; slipping pins may need oversize pins or pinblock work.
A piano holds about 18–20 tonnes of string tension. If a fix means opening the action, turning tuning pins or working near the strings, leave it to a technician.
In Israel
In Israel the swing between humid coastal summers, hamsin heat waves and AC-dried rooms is hard on tuning stability. Many owners find their piano drifts most at the change of seasons, so tuning in spring and autumn makes sense.