What was encaustic

The inventory lists from the shrine of Apollo at Delos from the 3rd century BC refer to "pictures framed and others with hinged covers, hung on the wall or placed on pedestals. The only technique specifically mentioned was encaustic". Kurt Gschwantler. Graeco-Roman Portraiture. Ancient Faces. Mummy Portraits from Roman Egypt. Ed. by Susan Walker. Metropolitan Museum of Art Publications, 2000, p. 16.

“Fain would the encaustics [cerae] of Apelles have portrayed thee." Statium, Silvae 1,1, 100.

"The painter chooses with great speed between his colours which he has placed in front of him in great quantity and variety of hues, in order to portray faithfully the naturalness of a scene, and he goes backwards and forwards with his eyes and with the hands between waxes and the picture." Seneca, Epigrams 121, 5.

"And you who [...] paint pictures [tabulamque] in encaustic colours". Ovid, Fasti, 3, 831.

"Some have employed the vivid delineations and colors of encaustic paintings [khrocótou grajh z ]". Eusebius Pamphili, Vita Constantini, 1, 3. (3rd-4th century AD).

"He exhibited for everyone to see upon a panel placed high aloft at the vestibule of the imperial palace [...]. By means of [this] waxen painting, was showing to everyone…" Eusebius Pamphili, Vita Constantini, 3, 3.

"Grace of feature? The clay of the statue and the encaustic of the portrait holds its impress better". Sidonius Apollinaris, Letters, 7, 14, 5. (5th century AD).