Dark on light. Letterpress ink, as a rule, is pretty transparent. If you try to print a pale color on top of a darker color, it probably won’t show up. (One exception: silver ink on dark paper can work pretty well - See more at: http://sycamorestreetpress.com/blog/behind-the-press-8-tips-for-letterpress-design/#sthash.BCmV0I7p.dpuf