A Broken Piano String: Why It Happens and What to Do
A broken piano string is something piano tuners meet quite often, and it is usually sorted out in one or two visits. Sometimes you hear a sharp snap in the middle of playing, and sometimes you simply notice a key that suddenly sounds thinner or a little out of tune. Here we explain why strings break, how to recognize it, and what happens from the moment you call us until the note sounds whole again. If you would like to get to know the strings themselves first, and how they create the sound, our guide on how a piano works explains it.
Why a piano string breaks
A piano string is made of high-quality steel, stretched with great force, and very durable. Over the years it takes millions of hammer blows, and the metal gradually weakens. High humidity adds rust, mainly where the string bends around the pins, and there it becomes thinner and weaker. A string can also break when a piano that has not been tuned for a long time is brought back up to standard pitch, because all the strings take on extra tension at once. Very loud playing in the top section, where the thinnest strings are, can end the life of a veteran string, especially when the hammers are already worn. In most cases it is simply a matter of age and time, and not of anything the player or the tuner did.
How to tell a string has broken
Across most of the keyboard each key sets several strings in motion together. So when one string breaks in the middle or upper section, the key keeps playing, but the sound comes out weaker or slightly unclean. When a bass string that stands alone breaks, the key mostly makes the sound of the hammer. If you open the top lid, you will usually see a curled string end near the tuning pin, since that is where most strings break. It is a good moment to take a photo, note which key it is, and call us.
What to do until the tuner arrives
The rest of the keyboard is yours to enjoy as usual, and that one key is best touched gently. The strings left on that note now take the full blow of the hammer, and a soft touch keeps them well until the replacement. A piano string carries tens of kilograms of tension, so the replacement is left to the tuner, who comes with the tools and with wire of the right gauge. The tuning pins also stay as they are until the visit, and if the string end lies loose inside the piano, you can leave it where it is.
How a piano string is replaced
A string in the middle and upper sections is plain steel wire, and the tuner matches new wire to it by measuring its gauge precisely. Bass strings are wound with copper, and each one is made to the measurements of the original string, so sometimes their replacement happens on a further visit. When a bass string breaks on a note that has two strings, it is common practice to replace both, so the two voices sound as one. At Zohar Pianos, string replacement is done in your home, anywhere in the country, and on the same visit the whole piano can be tuned as well. Such a visit takes between two and three and a half hours, depending on the piano.
After the replacement
A new string keeps stretching during the first weeks, so it drops slightly in pitch until it settles. On an older piano the tuner will tell you whether other strings are worth keeping an eye on, and we wrote about what the years do to a piano in our guide to an old piano at home. Stable humidity at home extends the life of the strings, and the recommendations are waiting in our guide to piano care and humidity. And if a string breaks on your piano, or a question comes up about the sound of a single key, we are here for you.
Links: book a piano tuning · how a piano works · how a piano is tuned · piano care and humidity
FAQ
Can I keep playing when a string breaks?
Yes, on all the other keys. The key whose string broke is best played gently until the replacement, because the strings left on it now take the full blow of the hammer.
Why do piano strings break?
Usually because of age and weakening of the metal, rust caused by humidity, or extra tension when a piano that has not been tuned for a long time is brought back up to standard pitch.
Where is a broken string replaced?
In your home. A wound bass string is made to the measurements of the original string, so sometimes it is fitted on a further visit.