Very interesting question! The answer may depend on the type of ink
and paper. My gut feeling is that to coat white paper it
would be best, from an environmental point of view, to use
UV curable or maybe water-based inks (on a modern press).
But to compare colored paper with printing color on paper
seems like its an apples and oranges comparison. We'd need
to compare the impacts of using the inks with the impacts of
dying paper at the mill. I wouldn't be surprised if very
similar chemicals are involved but that the processes and
environmental impacts are different. It would be
interesting if somebody has done a life-cycle type of
comparison of these two options. Determining Great Printer
practices is not easy.
Is it better to print on colored paper or to use a screen to coat
white paper the same color?