As a culture, we get attached to the piano in our homes. It is easy to overlook or forgive things like buzzing strings, buzzing keys, or the fact that it no longer holds a tuning.
Performance degrades over time, often incrementally until it can no longer be ignored. Pianos are built to last for decades, but not forever. Pianos have two lives, the musical life and the cabinet life.
The cabinet may stay intact long after the mechanical functionality of the instrument has died. The overwhelming majority of pianos are designed to last about years. There is approximately 40, pounds of tension created by the strings of a piano, which translates to about pounds of pressure on the soundboard. All day and all night, a piano is resisting the force attempting to twist it into a pretzel. After about 40 years of the wood in a piano expanding and contracting with seasonal humidity changes, we start to see more cases of soundboard cracks, splits in the bridges, soft-spots in the pinblock and separations in the back-frame or rim.
If the piano was heavily played, the action parts may also be worn out. These issues prevent a piano from functioning properly and the cost of repairs would far exceed the market value of the restored piano.
Gifting an old piano to a student pianist frequently seems kind and generous, but just as frequently the old piano causes a student to struggle with accurately reproducing the techniques learned during lessons. Students need a piano to hold a tuning for 6 months or more so they can learn to recognize proper pitch. Once a piano ceases to do these things reliably, it becomes a liability to any student who plays on it.
