ENCAUSTIC. — It is among the oldest known types of painting with an advanced technique; essentially, encaustic painting can be defined as that which uses wax as a binder and is subjected to a hot process (*ceris pingere ac picturam inuere*, says Pliny).
Documented in Egypt as early as the 7th century B.C., it then passed into Greece as a typical technique for painting on stone and marble and, subsequently, in the decoration of sculpture and architecture. Certainly used by Polygnotus, it was refined in the 5th century B.C. and reached a high degree of development with the major painters of ancient Greece: Nicias, Aristides, Pamphilus, Pausias, Thespes, etc. The Fayum mummy portraits, from the 1st to the 5th century A.D., are among the most important surviving documents of encaustic painting.
Research on the technique of encaustic was very fashionable in the 18th century, when attempts were made to revive the process, and there were artists such as Menges and scholars like Requeno, Viglioli, and Donner, who conducted thorough studies to reconstruct the various methods of encaustic used in antiquity.
From two passages in Pliny (*Natural History*, XXXV, 39, 41), supplemented by references from Lucian, Varro, Vitruvius, it is possible to reconstruct the three ancient techniques of encaustic: the wax, the cestrum, and the brush.
In the first, a hot priming layer of wax—perhaps mixed with the basic or preparatory color—was applied with a cautery or metal rod, with which the other colors were then added. This technique was used for painting on stone, marble, and even wood. The second was limited to encaustic on ivory: the *cestrum*, a rod pointed at one end (to fix the hot wax on the smoothed surface) and flat at the other (like a spatula for subsequent hot retouching), was used. To these two techniques was added a third, perhaps around 400 B.C. The brush, hitherto known only for tempera and fresco painting, was employed to apply directly—on both stone and wood—the hot wax already prepared and thinned with color. Pliny states that this technique was also used in coloring ships, as the color thus applied was resistant to sun, salt, and wind.
Although modern opinions on the technique of Pompeian and Roman paintings are no longer unanimous regarding the use of encaustic (recent studies have shown, for example, that the paintings in the House of Livia on the Palatine are frescoes, the wax being entirely from later restorations), it is certain that the technique of encaustic persisted after the fall of the Empire, in the aforementioned Fayum encaustic portraits and in other Byzantine examples, at least until the 6th century.