A new finish question

[Robert Goodale]

Howdy all,

I have a 20 year old Kawai UST-7 that I am interested in selling.
Before I do, however, I would like to pretty it up.  It has multiple
small scratches and other various marks which I will fill in/rub out,
etc, (former school piano).  The original finish does not appear to be
lacquer nor polyester.  I am suspecting some sort of polyurethane
hybrid.  It is somewhat harder than lacquer but not as hard as poly.
(Don, perhaps you could take a guess at what this is?)

I thought it might be a worth while experiment to put a coat of
polyurethane on it followed by sanding and then rubbing down with
rotten stone to a satin finish.  I have never done anything like this
on a piano before but it seems like it might work here.   Another
reason I thought this could be good is because the thick filling
properties of polyeurthane would probably fill and/or hide many of the
blemishes.  This is of course assuming that the present finish,
whatever it may be, will accept a fresh urathane finish on top.
Obviously the only way to test this is to apply a coat to a small spot
somewhere.

Does anyone have an opinion on this or has used polyurethane on a
piano before?  Note:  This is a used studio piano that I want to make
look pretty in a hurry.  I DO NOT want to strip down and refinish it!

Thanks,

Rob Goodale, RPT
Las Vegas, NV