I have some sym­pa­thy for the Riso­graph peo­ple.  Their process isn’t like ours: using mov­able types, but they oper­ate with the same lim­i­ta­tions — a sin­gle colour each pass and a lim­it­ed means of reproduction.

This guide from the Hato Press explains the lim­i­ta­tions — and the qual­i­ties of Riso print­ing — beautifully.

I also stum­bled on this colour chart from Fredk. Aldous of Manchester –

Head­er image: Riso­graph flickr pho­to by Yan­nic Mey­er shared under a Cre­ative Com­mons (BY-NC) license