I just bought a few old film holders, 4x5. When I remove the dark slide and the lift the bottom flap I see that on the back plate there is a little paint missing and a small patch of bare metal. Will this cause problems or should I paint it? If so, what sort of paint is recommended? Thanks.
I've used Rustoleum brand flat black spray paint with success on many holders. Mask the frames and give a light coat. If you still have metal showing through, another light coat. Avoid trying to do this in one go.
I second the idea of using a Sharpie for small nicks.