Finishing of Stringed Instruments

[Bob Zauke <bzauke@heartland.bradley.edu>]

My name is Bob Zauke from Normal, Illinois, USA and I am new to
this list (and to the net). I apologize in advance if this post
is improper to this list. I am an avid woodworker and have been
refinishing/retouching pianos for a local music shop. They have
asked me to restore/repair/refinish various stringed instruments
from their lease program. In lieu of formal training, I am 
attempting to learn more about sealers/stains/topcoats and 
methods of application. I can appreciate the resonant properties
of the wood and I suspect that any finish will tend to degrade
the resonance and therefore the finish should be thin, should
not penetrate into the pores of the wood and is for protection
and cosmetic purposes only. I am only guessing at this point.
Can anyone help to explain the basics to me or steer me in the
right direction? I can find no books or articles and there is
no one I can ask locally. Any help would be greatly appreciated.

Thank you for your time,
                Bob Zauke