As has already been pointed out, it would be foolish to use any
material already thirty years old, including rubber cloth.  The
material will already have started to deteriorate from age.

Regarding Bilon and Polylon, I seem to remember that Art Reblitz warns
against their use in his rebuilding book.  Apparently, builders started
to use modern alternatives in the 1970's, only to find that less than
ten years later, these modern substitutes were failing.

I'm sure we all know people who own players that are working on their
original systems.  So why try to find a substitute for a time-proven
material.  Modern isn't always best.  Stick with a tried and tested
formula.  To have to buy all new rubber cloth for the entire player
won't break the bank.  A new set of piano hammers and tuning pins would
probably cost as much, if not more.  So in the grand scheme of things,
the cost of the replacement cloth is a minor outlay.

Steve Toyne,
Boston, Lincolnshire, England