Stippling is the technique of using small dots to simulate varying degrees of solidity or shading.
In a drawing or painting, the dots are made of pigment of a single color, applied with a pen or brush; the denser the spacing of the dots, the darker the apparent shade—or lighter, if the pigment is lighter than the surface. This is similar to—but distinct from—pointillism, which uses dots of different colors to simulate blended colors.
In printmaking, dots may be carved out of a surface to which ink will be applied, to produce either a greater or lesser density of ink depending on the printing technique. In engraving, the technique was invented by Giulio Campagnola in about 1510. Stippling may also be used in engraving or sculpting an object even when there is no ink or paint involved, either to change the texture of the object, or to produce the appearance of light or dark shading depending on the reflective properties of the surface: for instance, stipple engraving on glass produces areas that appear brighter than the surrounding glass.
The technique became popular as a means of producing shaded line art illustrations for publication, because drawings created this way could be reproduced in simple black ink. The other common method is hatching, which uses lines instead of dots. Stippling has traditionally been favored over hatching in biological and medical illustration, since it is less likely than hatching to interfere visually with the structures being illustrated (the lines used in hatching can be mistaken for actual contours), and also since it allows the artist to vary the density of shading more subtly to depict curved or irregular surfaces.
Images produced by halftoning or dithering and computer printers operate on similar principles (varying the size and/or spacing of dots on paper), but do so via photographic or digital processes rather than manually. These newer techniques have made it possible to convert continuous-tone images into patterns suitable for printing, but artists may still choose stippling for its simplicity and handmade appearance. The Wall Street Journal features stippled portraits known as hedcuts in its pages, as part of its long-standing avoidance of photographs.
A further use of stipple indicates the damage caused by spider mites which make tiny white spots on plant leaves which can coalesce until the entire leaf appears silvery.