If I were sealing the metal valve plates in a player today then I would
use burnt shellac.  Why?  Because the last Standard player I did had
been sealed with PVC or something like it that is rubbery and sticks
well.  It was a total pain to remove and you could not remove the valve
plates easily.  I cannot stress to you how much I stressed removing
that junk.

Don Teach - Shreveport Music Co.
Shreveport, Louisiana