For playfield touch ups, I use enamel paints.

The benefits are a longer lasting and harder surface. The yellow-red spectrum does not change colors as it cures and can be playtested within minutes of application.

Make sure to use gloss and not matte paints as the finish will not be the same as the rest of the pf paint.

Please note that I have not tried to clearcoat over enamel paints and am not sure what the chemistry would be like for bonding between the paint and the clear. If anyone has experience or has tested this, I'd like to know more.

Get a color wheel. Learn how to use complimentary colors to get correct matches. Secondary and tertiary color mixing may be necessary for teal greens and darker oranges.

Finally, the mechanical dust in games is actually a dark blue. This will mess with your playfield "whites" especially on non diamond plate/ early SS and EM games.

Make a mistake? Not to worry... Wipe it off with naphtha or cover it up with another layer of opaque enamel paint.

Enjoy!

c2s