Symptoms
- A loud bang or twang, sometimes while nobody was playing
- One note suddenly sounds thinner, weaker or out of tune with itself
- A bass note goes almost silent or makes a dull thud
- A loose wire is visible inside the piano or rattles against other strings
Likely causes
Rust and corrosion
Humid air oxidizes the steel wire, especially where it bends around the hitch pin and tuning pin. Rusted wire loses strength and can snap with no warning.
Age and metal fatigue
Strings on pianos 50 years or older have been flexed by millions of hammer blows. Old wire becomes brittle and breaks more easily, particularly during tuning.
Pitch raise on a neglected piano
When a piano that is far below pitch is brought back up, every string takes on extra tension. Old or rusty strings are the ones most likely to give way.
Very heavy playing
Repeated fortissimo playing in the treble, where strings are thinnest, can break a string, especially if the hammers are hard and worn into grooves.
What you can safely check yourself
- 1Play each note in the area slowly and listen for the one that sounds thinner or different, then note its position (count from the lowest key).
- 2Open the lid and look, without touching, for a wire that is curled, slack or lying across other strings.
- 3If a broken end is clearly loose and resting on other strings, you can lift it gently away so it doesn't buzz, wearing gloves and protecting your eyes.
- 4Check whether other strings look dark brown or rusty; this tells the technician how fragile the rest of the piano is.
- 5Keep playing the rest of the piano normally, but avoid striking the affected note hard.
What not to do
- Never try to replace, splice or retension a string yourself. Each string carries roughly 70–90 kg of tension and can whip and injure you.
- Don't turn the tuning pins to 'tighten things up'; you can break more strings or crack the pinblock.
- Don't play hard on the remaining strings of that note's unison, they now carry the full load of the hammer.
Quick fixes vs. call a pro
You can usually handle it
- Identify which note is affected
- Move a clearly loose end away from other strings
- Check how rusty the other strings look
- Keep humidity in the room stable
Call a technician
- Replace or splice the broken string
- Fit a new bass string made to measure
- Tune the new string over several visits
- Assess whether more strings are at risk
What a technician will do
A technician removes the broken wire and installs a new treble string from a coil of matching gauge, or orders a custom-wound copper bass string made to the old one's measurements. A treble string usually takes under an hour; a bass string may need a week or two for manufacture. New wire keeps stretching, so it needs to be retuned several times over the following weeks before it holds pitch.
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 coastal cities like Tel Aviv, Haifa, Ashdod and Netanya, salty humid air rusts piano strings much faster than inland. A dehumidifier in summer and keeping the piano away from open windows facing the sea will noticeably extend string life.