This is in answer to John Tuttle's article about piano finishes
in 000520 MMD.  A lot of the confusion is due to terms being used
interchangeably.

Shellac means only one thing: it is derived from the Lac bug, an
insect native to India and its neighbors, I believe.  It seems hordes
of these bugs live in the trees and exude a strange substance, which
they use to create living quarters; its kind of an elaborate version
of termites and their mud tunnels.

These structures grow to considerable size in the tree branches.
Ultimately, they are cut down, broken apart, dissolved in alcohol,
purified, and dried out to create orange shellac flakes.  While shellac
finishes are my favorite, they are vulnerable to being damaged by
alcoholic drinks.

Lacquer means at least two things: Nitrocellulose lacquer was first
used on pianos in the mid 1920's, and effectively ended other materials
being used for clear finishes.  This lacquer dried fast and made
finishing less costly.  I don't think it looks as good as a good
shellac finish, and it cannot be repaired like shellac, but the public
accepted it.

The second meaning for lacquer is when references are made to Chinese
Lacquer.  This material goes back countless centuries, and I do not
have any information on it.

Varnish is apparently anything you want it to be.  To say it is
"resins in solvent" is to say everything and nothing.  If this weren't
confusing enough, all three terms are nouns, but they are also used as
verbs: "He varnished the wood."

My test for a finish is to see if alcohol will make an inconspicuous
area sticky.  If it does, it is shellac or a shellac-based varnish.
A good craftsman can restore a shellac-based finish any number of years
old.  The alcohol solvent blends the old and new materials together.
This technique is sometimes referred to as "French Polishing", although
that technique also allows a finish to be applied to bare wood.

If alcohol will not soften the finish, it is probably a post 1920's
spray lacquer, or non-shellac-based varnish.  I do not believe these
finishes can be repaired as satisfactorily as shellac.

To get back to Mr. Tuttle, an expression such as "Shellac for the
soundboard and Varnish for the case" means different things to
different people.  Until we use strictly defined terms, the parable
of "The Blind Men And The Elephant" will be re-enacted over and over.

Randolph Herr