Ancient painting techniques

The paintings of the Vesuvian cities provoked immediate amazement upon their discovery, but it tookmore than two centuries to understand the technique used to create them. The decorations took the formof frescoes: the colours were laid onto plaster while it was still wet, so as to be indelibly embedded in itupon drying out. Some details could be added later, either by reactivating the process of colourabsorption in the plaster of the area concerned, or by simply painting over it.

The last layer of plaster, the so-called intonachino, was applied at the last moment to the portion of thewall destined to be worked on that day. The entire decorative pattern was then quickly engraved on it:using fishing line to create guidelines, the pictor parietarius squared off the structure of the painting andemployed punches and compasses to outline the architectural elements of the background and framealong with the purely decorative accessory elements, which would then be finished with colours.

The pictor imaginarius was responsible for creating the figurative paintings, which required a higher level of specialisation. These pictures were painted once the work of the pictor parietarius was complete: only then was the last layer of plaster (the intonachino) applied to the section of the wall destined to be painted.

A few small paintings were found lying on the ground in the gymnasium in Herculaneum, probably waiting to be repositioned after the wall had been restored.

Thanks to tools such as the proportional compass, which consisted of two arms hinged two thirds of the way along, a subject could be reproduced with different dimensions. The painting of Perseus freeingAndromeda, from the House of the Prince of Montenegro in Pompeii, which measures approximately one metre across, has an exact replica in a painting from the gymnasium of Herculaneum, which is only 38 cm wide.

Literary sources reveal the names of the great Greek painters of the Classical and Hellenistic ages, but there is scant information about Roman painters. Through Pliny, the names of the painters who decorated Nero's Domus Aurea have lived on: Fabullus and Studius (or Ludius). However, written sources tell usal most nothing about the numerous artists active in Pompeii: a single signature, Lucius pinxit, was found beneath the painting of Pyramus and Thisbe in the House of D. Octavius ​​Quartio. Pliny also names a painter, Iaia of Cyzicus, who lived around 100 BC and specialised in portraits. Two paintings from theArchaeological Museum of Naples document the activities of painters: in both of them, a woman is painting a picture that lies on an easel.

The Vesuvian cities have not only handed over the paintings but the tools used to make them too including the pigments needed to produce the colours. The pigments used are described in detail by Pliny. These could be of mineral, vegetable or animal origin: the latter were among the most expensive such as the purple obtained by macerating molluscs or the black created by burning ivory. Based specifically on their value, Pliny categorised them as "plain" (more common and affordable for everyone)or "florid" (more expensive but brighter). Ochre was used for yellows and, when heated, for reds. The most precious red was cinnabar, the minium of the ancients, which had a rich, brilliant hue. For greens they turned to minerals, the most precious of which was derived from malachite. The most wide spread blue was produced in Alexandria and was known as "blue frit"; or Egyptian blue; from the time of the LateRepublic onwards, it was also produced in Pozzuoli by a friend of Cicero, C. Vestorius. More valuable blues, meanwhile, were armenium, which was obtained from azurite, and scyrthicum, made from lapislazuli. Whites were calcium carbonates, whilst blacks derived mostly from the combustion of plants(resins, barks, etc.), although those produced by burning bones were also prevalent.