Riso plotter drawings
We taught an old pen plotter to separate its own colours.
A pen plotter from 1987, a Risograph from 2004, and a lot of paper that did not survive the introduction.
The idea was to let the plotter draw the separations rather than the artwork — one pass per ink, registration deliberately loose, so the misregistration becomes the image rather than the error. Riso already drifts by a millimetre or two. Adding a plotter's own backlash on top produces overlaps you would never choose on screen.
Adding a plotter's own backlash on top produces overlaps you would never choose on screen.
What we learned is that the interesting range is narrow. Under about half a millimetre of drift it reads as a printing fault. Over about three it reads as two unrelated drawings. In between there is a band where the eye assembles a third colour out of the overlap and the image gains a depth that a single clean pass never has.
Forty prints, eleven of them worth keeping, and a much better instinct for how far a two-colour job can be pushed before a client's printer calls to complain.