Um ... I've developed cyanotype, as I've had almost 3 years of drafting classes between high school and college.
After you finish your technical drawing, you trace the whole thing onto velum, which is semi-transparent. To make copies, you then place the drawing against the cyanotype paper, and expose it to UV light. (you can use sunlight, but most shops will have a system of rollers and UV lamps to handle longer drawings, or a large lightbox that might be able to handle 3'x4' or so.)
After the UV exposure, the dye on the (white) paper will turn blue where the drawing didn't block the light. You then wash off the paper to remove any of the uncured dye, and you might send it through another chemical wash to deepen the colors.
So ... you have a white paper, that's coated in a blue ink. Where you see white lines on the blueprint, you're seeing the paper, not the dye.
And there's a similar product used in the screen printing industry. I'm not sure what it's called, but it's this sheet of coated acetate. You place your image on it, expose it to UV, and then when you wash the unexposed part away, the whole thing gets kinda gooey. You then press the sheet against your silkscreen (and by press, I mean, with a *lot* of force ... rollers, etc, to force it into the screen), let it dry, and then peel away the acetate. You mask off the surrounding area, and you're reading to print shirts or whatever. (for single colors, at least ... you'll want a carousel & spot dryer for multi-color)