muffler felt for grands

[Newton Hunt]

The reason this is not a common feature on grands is that
the felt is so flaccid it will not remain effect for more
than a few minutes.  If you use something stiffer it will be
noisy.  I have seen buckskin used on fortepianos but doubt
you can install a similar device because the hammers of a
modern grand are so wide.

Nearly impracticable if not impossible to make work.

		Newton