I just ordered a sampler pack from www.filmphotographyproject.com for my recently acquired Graphic View 4x5. Can't wait to get out and shoot with it! Mat Marrash has some pretty cool images shot on the stuff. www.matmarrash.com
The screens that hold the X-ray film, give off green, or blue light. That is what makes the film holder work. The idea being that you would need less X-ray to
produce an immage. Prior to that we had "cardboard cassetts." They had no screens, and needed more X-ray to produce a immage. The immage was great, but
at a cost of exposure.