Has anyone here handcolored scala or other B&W positives? Will they stand up to the heat of projection or do they need special mounts? I have a few I want to try it on and I do have access to a microscope that I'd be able to work under.

Oil paint is not overly subject to problems with heat as far as I know, but oil residues can be flamable so I would use caution until you have a good idea of how hot it will get. Oil paint uses oil and turpentine as a transport for the dyes and pigments, which dry slowly over a period of years. Photo oils dry faster due to various reasons, but the dried oils could still be flamable. I wouldn't think it would be a problem, but as I stated above, I would use caution at first.

- Randy