Damon,  I don't think everything made of wood in the 1920s was finished
with dark colors; rather, the varnish has darkened with age and
exposure to light and moisture.

Most times, when you strip off the old varnish, it reveals light wood
with beautiful grain patterns, and if you refinish with clear varnish,
as was done originally, the result is a beautiful, light-colored
finish, that must duplicate what it looked like originally.

Larry Lobel
Virtuoso Piano Service