Glenn FleishmanOn September 5, 1946, the St. Louis Post-Dispatch switched the printing of its color comics from relief letterpress to rotogravure. Rotogravure was mostly limited to fancy sections, including fashion, color photography, and advertising. The paper seems to be the only one in United States that ever chose to use the very expensive rotogravure process for comics. In these panels, you can see and compare relief versus rotogravure.
The comics with Dagwood and the chicken are printed by relief letterpress (photos 1 and 3). The comics with Dagwood in his pajamas are printed by rotogravure (photos 2 and 4). Compare and contrast!
Rotogravure is an incised or intaglio process. This contrast with letterpress, which is a relief or raised process. Rotogravure relies on wells of ink, which vary in depths to simulate gradations of color.