Why I use leather.  First it is original to the machine.  It worked

when it was new.  It has less friction than other materials so valves

can seat.



The greenish residue found on valves is verdigris.  I don't understand

the chemical process but it occurs when certain leathers are used with

brass.  Leather tanned with tannic acid is the leather that reacts with

brass to form verdigris.  Leather that is vegetable tanned does not.



Perhaps one of you chemists out there can offer a solution.  The tan

colored leather sold by Player Piano Co. in the 1970's was acid-tanned

leather that reacted with brass.  I have a Coinola that I am redoing

because of the leather.  The pneumatic cloth sold at that time has held

up very well.



Don Teach

Shreveport, Louisiana