Film positives for screen printing will always work best when the films are dark and opaque. The film positive must be dark enough to block light during the screen exposure process. If your film are not dark then your screens will not expose correctly and you will not get a good stencil/screen to make a good print. We use waterproof inkjet film for our film positives. We print our film positives with an Epson inkjet printer. We also use Accurip to print our film positives. Accurip is a third party software that uses a special "language" to communicate with your printer, letting your printer know "how to print halftones" or how much ink to lay down on the film positives. Whatever printer you use- just make sure you get dark opaque film positives. We also use UltraSeps color separation software to separate our art before printing film positives.