In 051222 MMD, Mark Kinsler wrote:

> I think that cellulose nitrate plastic is better known as celluloid,
> and that its use is banned, at least in the US, for anything but
> Ping-Pong balls.

Cellulose keytop material is currently sold by Schaff Piano Supply
Company under the name "Pyralin (Ivorine)".  It is indeed cellulose
nitrate, tempered (softened) by the addition of camphor.  When Pyralin
-- even 50-year-old material -- is cut with a knife, the characteristic
odor of camphor is obvious.

This material is highly flammable, as noted by Mark.  I have demonstrated
this fact to blind students at the Piano Hospital by lighting one end
of a discarded natural [white key] keytop and tossing onto the sidewalk.
The entire keytop is reduced to ash in less than 30 seconds, and the
heat is readily felt by the blind students.

John D. Rhodes, RPT
Vancouver, Washington