The formula of the red, shiny and intense colour that dominated Pompeii's wall paintings 2000 years ago has been discovered by an Italian researcher.
Buried in the catastrophic eruption in 79 AD, the brilliant Pompeian red has been preserved forever by the lava of Mount Vesuvius and still makes an impressive show in several frescoes.
"Though it consists of simple cinnabar pigment, Pompeian red is really unique. It certainly stands out when compared to normal cinnabar paint layers," said Daniela Daniele, a researcher working at Berlin's
Staatliche Museen.
Cinnabar is mercury (II) sulfide, the principal ore of mercury.
Daniele analysed the stratigraphies of some samples from Pompeian villas featuring the unique red and compared them to other ancient Roman wall paintings containing normal cinnabar paint layers.
Her aim was to discover why there was a dramatically different chromatic effect with the same mineral pigment.
In the case of Pompeian red, natural cinnabar was processed with particular care, which included what Daniele called "purification, grinding and dimensional control".
"The finer the grains are, the more brilliant and covering the colour is. But there is much more," Daniele said.