Extract

For the technique of panel-pictures, most of which were executed on wood, we have little direct evidence, but *Pliny (1) divides his account of Greek painters (HN35) into those who worked with the brush (penicillo) and those who painted in encaustic. The distinction was probably between a tempera technique (in which pigments are mixed with an organic medium such as size to help them to adhere to the surface) and a method of applying colours with heated wax, using either a brush or a spatula. Encaustic was also suitable for painting on stone, and was evidently employed for colouring statues, which explains Pliny's statement that the technique was perfected by *Praxiteles. In wall-painting the famous murals of the 5th cent. bce by *Polygnotus and *Micon seem to have been on wooden panels attached to the walls, but the normal method was to paint on coats of plaster, using fresco. In this technique the pigments are applied while the plaster is still soft and are fixed by a chemical reaction between lime in the plaster and carbon dioxide in the air. That fresco was used in antiquity has often been doubted, but the account of *Vitruvius (De arch.