Quote Originally Posted by rduraoc
Another question: once the paper is ready, only sunlight or UV lamps will be able to impress it, right? Normal house lamps (fluorescent or tungsten) don't emit in the UV band?
Much UV light is generated in flourescent lights. Perhaps the coating in the lights blocks some of it, but incandescent lights should be safer. The yellow incandescent bug lamps are better yet.

When I did alternate processes long ago we often used enlarged half-tone negatives. Printing time was shorter than when using continuous tone negatives. Litho film for halftones might not be expensive. Finding a screen for making the halftones could be a problem, though, if you can't improvise one. If you have a way of scanning prints, you could print halftone negatives on transparancy material in an inkjet or laser printer. I haven't tried printing such negatives, and their quality didn't look very good. However, it does use common material.