The Domus Aurea and its colours

The precious and refined imperial palace amazes again with yet another exceptional discovery linked this time to the workshops that created the frescoes that decorated Nero's sumptuous residence.

During archaeological investigations, two tanks were found that were used by the workers and artists of the Domus Aurea building site to extinguish lime and to store and process the coloured pigments that would have decorated the walls of the palace.

The pigments include yellow ochre inside an amphora, jars containing pigments in shades of red, but above all an extraordinary ingot of the precious Egyptian blue, ready to be ground.

An extremely rare find due to the large size of the block, 15 cm high and weighing 2.4 kg, because the pigment is normally found in powder form or in small spheres, as in Pompeii.

A pigment that does not exist in nature, Egyptian blue is produced artificially by baking silica, limestone, copper-containing minerals and sodium carbonate at high temperatures, as Vitruvius describes in his De Architectura, (VII, 11).

Known and used since at least the mid-3rd millennium in Egypt and Mesopotamia, it also spread to Rome where it was employed in pictorial decorations alone or associated with other pigments to achieve specific chromatic varieties and sought-after luminous effects.

One of the major centres of production and export of Egyptian blue is Alexandria in Egypt, but traces of it are also found in Italic territory, such as at Pozzuoli, or Pompeii where its name is mainly linked to its use in luxury contexts. The finding in Rome, where, as we have seen, it was used in imperial contexts, is therefore consistent and confirms the refinement and great skill of the craftsmen who executed the decorations in the palace, thanks to the use of rare and expensive pigments.

In the context of studies on the settings and materials of the Domus Aurea, Egyptian blue, which was also used in the Renaissance, as in Raphael's Triumph of Galatea, ideally unites, centuries apart, the artists who decorated the Domus Aurea with those who, with amazement and emotion, rediscovered it in the Renaissance.

Domus Aurea, Egyptian Blue Lingotto © Parco Archeologico del Colosseo, Photo by Simona Murrone