I have restored a number of plates and used the following technique with a lots of success. After doing the typical metal cleanup, repairs and priming. I spray paint the entire front side of the plate the color of the raised portion of the plate. Two to three coats are recommended. I would recommend an enamel with a hardner or some other "hard" type of enamel. After this has thoroughly dried, I spray the entire plate, front and back with the background color. This enamel does not have to be a "hard" in fact it is better not to be. After the paint has sufficiently dried you simply wet sand off by hand the background color of paint from the raised portion of the plate using 400 grit and progressively finer grits. After final buffing by hand the results should look like a plate that is fresh from the pen.
