Gouache is a water-based paint in which finely ground pigment is bound with gum arabic and mixed with an opaque white, giving a dense, matt finish that can cover the paper completely rather than letting it show through, as transparent watercolour does. It is also known as bodycolour, and in historical descriptions the two terms are often used interchangeably.
Opaque watercolour has been used since medieval manuscript illumination and was employed by miniaturists and botanical artists for its fine detail and strong colour. In the eighteenth and nineteenth centuries it was widely used for topographical views, landscapes, botanical and natural history studies, fan painting and architectural presentation drawings. English artists such as Paul Sandby used bodycolour extensively, and in Naples a thriving trade in gouache views of the Bay and the erupting Vesuvius supplied Grand Tour visitors. Designers, illustrators and poster artists of the twentieth century also favoured gouache for its flat, brilliant colour. Because it dries to a slightly chalky surface, gouache can crack or flake if the paper is flexed, and it is vulnerable to damp and abrasion. Collectors look for fresh colour, sound paint and paper, and original mounts. Like watercolours, gouaches should be framed behind glass and kept away from strong sunlight.
