OK in the 1960s you could get a two part paint. It used to be called Day Glo. The basic stuff was a white undercoat and the colour you wanted on top. There was a green but most were amber or yellow. I used to paint it on parts of model aircraft since I was partially sighted and contrast was everything. I imagine the paint underneath reflected most of the uv so that the top coat could convert as much as possible into the colour needed.
Brian