Look closely—very closely—at a Sunday comic strip in a printed newspaper. You might need the magnifying feature on a smartphone or a loupe, a small magnifying device, to see the dots that make up most areas of color on Sunday pages, and all of the tints in black ink Sunday through Saturday.
Clustered dots of varying sizes fool the eye into seeing tones. Just four ink colors—black, cyan (light blue), magenta (a rosy red), and yellow—can combine in different densities to form most colors, though some appear garish or washed out. Newspapers began printing color in 1894 using this process and continue today. The dots used to simulate tones are referred to generically as a screen or in photos as a halftone.
Cartoonists don’t create these dots—they’re added during print production. Cartoonists started with pen and ink on paper. Starting in 1894, their drawings were shot as photographic negatives, which were then exposed under intense light onto photosensitized zinc metal plates.
To add tints, cartoonists (or often an assistant or colorist) roughly marked up their drawings, indicating which grays or colors should appear in which areas. Comics syndicates created a limited set of colors to choose from based on mixing tints at different percentages, and those numbers would be marked on the comic. Some cartoonists used color pencil or watercolors on their original or a copy as an additional guide.
In production, engravers took these zinc plates—a single black plate for weekdays, and four separate ones for Sunday color comics—and painted around each area that needed tone using a water-soluble material called gamboge. They applied an oily ink to a sheet in a frame somewhat resembling a silk screen called a Ben Day screen that was covered with tiny dots for the desired tint. The engraver then placed the screen over the areas on the zinc plate that needed tint applied and used a burnisher to rub down the Ben Day pattern. They then washed the gamboge off. They might have to do this dozens to hundreds of times for a Sunday strip.