When I was lecturing, and employed by a medical institution that had an audiovisual department, I would give them a list of title slides I wanted, and what colors I wanted the words to be. It might be a bullet point list where I wanted the heading to be one color and the following text to be in a different color. They would typeset whatever I wanted and photograph it. They would print the text out in black on a high gloss paper which was bright white. I don’t remember what the film was, but high enough contrast that the type/Letters came out as perfectly clear on a perfectly black background.
I might have chosen deep yellow for the heading and Prussian blue for the text, but it varied. Typeface could be anything I wanted.
Then they’d take a 000 brush and, on the now mounted slide, paint over the clear text with Dr. Martin’s transparent water color dye. Any dye which went outside the letter didn’t matter because the surrounding film was totally black and transmitted no light at all when projected. If I was in a hurry they’d just give me the slides and I’d color them in.
Results were beautiful.
And, yes, this was the Eighties.