What I do for cyanotypes might also work for POP. When I want to make a cyanotype print from a normally developed negative I first make a contrasty print on variable contrast RC paper. I then contact print the RC print onto film to produce my negative, and use this negative to make the cyanotype. I use Fine Grain Positive Sheet film because it was inexpensive when I bought it, and you can also tweak the contrast of the film somewhat by how long you develop it. The fact that you can use it with a safelight in the darkroom is also nice.
Originally Posted by laverdure