Any thoughts, suggestions or solutions as to how a discolored dial can be restored? I've seen a number of dials on older watches that have become discolored with age. Particularly on light-colored dials, or metallic-finish dials. Especially the metallic dials, whether silver, or in some nice metallic color, like blue, green or red, after 30 or so years, the shellac, or lacquer, or whatever resin was actually used as a presumably protective coating, has started to yellow, in some cases approaching a sickly shade of brown.
The reason I'm asking is that I think it would be nice to restore such a dial, rather than wiping it clean and re-doing it all from scratch. Particularly when some of what would be getting wiped off is information you'd rather keep on the dial, like "Automatic", or "21 Jewels", or "150 m", or whatever. The alternative, like I said, would be to wipe it clean and refinish the dial. It's possible enough to re-do all the printing, but it'd also be a bit of a pain, not to mention that it probably would not match the original lettering.
I'd appreciate any thoughts or suggestions on this.