Just a comment about shellac and overcoating with a harder finish such
as a polyurethane.  From my experience, you have to be very careful
when covering shellac with another finish.  Shellac and poly are not
necessarily compatible finishes and you can have a real mess with
peeling and bubbling of your final finish.  You need to make sure that
you are using a de-waxed shellac as a base.  Beware that some
polyurethane compounds will still not be compatible.

Another suggestion for the amateur finisher, _never_ use pre-catalyzed
lacquer on anything.  I did a Steinway Duo-Art upright with a beautiful
deep wine full finish that now has to be redone as the new finish is
cracking and will need to be redone if it continues to do so.  I am not
looking forward to this as it is really miserable to remove.

Furniture shops and professional refinishers may have different
chemicals available but for those of us who are more hobby finishers:
beware!  I have always used good chemicals and I probably cannot
mention brand names here.  Be careful and make sure that the whatever
finish chemicals you use are compatible with each other.

Randy Hammond