Illustration by Balliol Salmon
Various drawing and painting media were used in early 20th century illustration: "There are very few technical limitations in general illustration. You may use charcoal, chalk, pencil, wash, oil-colours, line and tone combined—practically anything which will reproduce effectively. The minor periodicals use pen and ink, chiefly because the paper on which they are printed isn't suitable for tone work, but your readers want, as far as possible, as complete a representation of a subject as they can get, and full tone or colour can of course be suggested more easily by the tone mediums than it can be by line."
—Percy Bradshaw, quoted in the Artist Magazine, Aug. 1932, p. 248. Thanks, James W.