I recently listened to performances at the 1st International Chopin Competition of Period Instruments, and I noticed that the chords in the fortepianos used there (manufactured in the early 18th century by Pleyel and Erard) tend to continue on vibrating even after the pianists releasing the keys. It is as if their dampers are not as effective as those in modern pianos. A quick Internet search suggests that there are some professional pianists observing this.

The fortepianos reminded me of my grandmother's upright piano, which is of course modern but unmaintained for years. Its damper creates similar sound as the aforementioned fortepianos.

Thus my question is whether the observed property of the dampers in the fortepianos from that era is a bug or a feature. Is it caused by wear and tear during this 150-year period, or is it a historically accurate presentation of the kind of fortepianos that Chopin and his contemporaries played?

I recently listened to performances at the 1st International Chopin Competition of Period Instruments, and I noticed that the chords in the fortepianos used there (manufactured in the early 19th century by Pleyel and Erard) tend to continue on vibrating even after the pianists releasing the keys. It is as if their dampers are not as effective as those in modern pianos. A quick Internet search suggests that there are some professional pianists observing this.

The fortepianos reminded me of my grandmother's upright piano, which is of course modern but unmaintained for years. Its damper creates similar sound as the aforementioned fortepianos.

Thus my question is whether the observed property of the dampers in the fortepianos from that era is a bug or a feature. Is it caused by wear and tear during this 150-year period, or is it a historically accurate presentation of the kind of fortepianos that Chopin and his contemporaries played?