Via the CO2 blog, Gerry Giovinco explores the history of coloring via the color chart, a mix of CMYK values which was all folks had to work with as recently as 10 years ago. I remember once seeing an editor reduced to tears by having to spec a color guide from a color chart. It wasn’t pretty.
This Chemical color chart is all comics had to work with until the mid-’80s. All of the great comics of the Silver Age used just this palette.