Andrew Taylor wrote:

> I have learned the hard way that paint on a plate must be chosen
> carefully, as some lacquers and primers sometimes will have
> a chemical reaction with the "Japan-ing" filler underneath, causing
> it to crack or craze.

I have painted several piano plates in the past using a special piano
plate "gilding" powder mixed with clear lacquer.  The gilding powder
comes in different colors (shades of gold), and can be blended to make
a custom color if desired.

The powder is a bit expensive, so you might want to find a technician
that has some that would sell/give you a small amount (enough to paint
one plate).  I have not had any problem with any reaction to the finish
underneath from the lacquer on the plates I have done.  If you Google
on "piano plate gilding" you should be able to find a source for the
material (if not here on MMD), as well as the proper method to apply
it.

Happy painting!
Rich Ingram