[ Douglas Heffer wrote in 131113 MMDigest:

> I have seen Phonola pianos made during World War 1 which used
> a fine white skin for the striking pneumatics.  Rubber was not
> available at that time.  Maybe there is a confusion in materials?

I believe the thin white material you are referring to is zephyr
skin.  It is a very thin membrane made from lamb's intestines.
As it ages it becomes brittle and "paper like."

Zephyr skin is thinner and more flexible than rubber cloth, which
makes for very quick action.

Keith Taylor
Jefferson, Maine, USA