Pompeii’s Paint Workshops Were More Sophisticated Than Once Thought
The research also discovered a formerly unknown light green pigment.
In the wake of the midsized earthquakes that struck Pompeii in 62 C.E., the city’s affluent residents got to work redecorating. Much like today, they outsourced the task to others: painting workshops that specialized not only in deploying illusionistic effects and linear perspective on frescos, but also in mixing natural and synthetic pigments to create a broad spectrum of colors.
When Mount Vesuvius erupted in 79 C.E., burying Pompeii in ash and pumice, it preserved a peerless body of frescos as well as evidence of the city’s paint workshops. Two sites are of particular interest to archaeologists.
First, the residence of a pigmentarius, a paint dealer, known as the House with Workshop. This produced the largest cache of pigments ever found in Pompeii, 150 pots in all, alongside other tools of the trade including stone pestles, scales, spatulas, and a whetstone. In a sign of work having abruptly halted, red and black tallies on the wall record the workshop’s activities.
Second, the House of the Painters at Work, a private house. When it was excavated in the 1980s, archaeologists found 50 small ceramic pots containing pigments and the imprint of a basket used by painters to transport pots from workshop to work place. Interrupted by the eruption, the unfinished decorative schemes and underdrawings have allowed researchers to better understand the processes of period painters.
New research carried out at the Archaeological Park of Pompeii has focused not on the frescos but the paint itself, with an analysis of 26 pigments, some of which hadn’t been studied before. The findings, which were published in the spring edition of the Journal of Archaeological Science, break down the chemical-mineral composition of the pigments to suggest how they were prepared before being painted on the walls of Pompeii’s houses.
With previous studies having damaged Pompeian pigment materials, researchers used onsite digital microscopes, a novel non-invasive approach, that laid bare “the remarkable expertise of Roman painters in mixing and proportioning various raw materials to achieve a wide spectrum of nuanced shades.”
Pompeian paint workshops relied on two pigments more than any others: Egyptian blue—a complex mixture of sand, copper minerals, calcium carbonate, and ash—and red lead, which was created by roasting lead white. Egyptian blue, for example, was the base for grey and used to brighten yellow and green. Red lead not only enhanced red ochre, but was also the starting point for a range of pinks and acted as a tone corrector for violet. Researchers wrote that the extent to which craftspeople altered firing times, adjusted pigment particle size, and included white pigments to achieve the desired shade of blue was previously unrecognized.
Researchers also discovered a formerly unknown light green pigment that was formed by mixing red ochre, Egyptian blue, and a material containing baryte and alunite, a sulphate deposit formed around volcanos by pressure, heat, and water. It’s the earliest known use of barium sulphate being used as a main coloring material in the Mediterranean. While volcanic systems that produce baryte and alunite are widespread in Italy, future research will aim to accurately identify its source.
The result of comprehensively detailing the pigments comprising Roman paints, researchers write, is that conservators can now replicate mixtures to match the originals “ensuring that restored sections of frescoes are chemically and visually consistent with the original works.”
For now, at least, this is most likely to be used in the digital replication of Pompeian frescos.
By Richard Whiddington.
