While talking with the finishing foreman for Mason & Hamlin in 1993,
I asked about Mason & Hamlin's treatment of the soundboard:

  "A soft lacquer for the soundboard rather than varnish."

His opinion was that varnish was best for violins, producing a more
mellow tone, while a soft, more flexible lacquer produced a more
desirable tone for pianos -- more brilliance.  (Stay away from the
hard, Magnalac type lacquers.)

Of course, the Mason & Hamlin case finish was a high quality lacquer
(numerous coats) that was wet-sanded and hand-rubbed with 0000 steel
wool, pumice and a wool lube after the last coat.

Gary Bagley

[ Magnalac(tm), a product of M. L. Campbell Co., is advertised
 [ as a "precatalyzed lacquer".  -- Robbie