“The Use of Colours and the Brave Show They Make” – Pigments in Roman Frescos
The pigments available to Roman artists were wide and variable, allowing them to produce high quality pieces of wall art such as this example from the Villa Oplontis. Copyright image by Natasha Sheldon, all rights reserved.
Roman frescos became famous for their artistic style; sometimes crude, often simple, at other times fantastically complex. The Roman architect Vitruvius deplored this fashion for imaginative resetting and condemned such works as ‘paintings of monstrosities.’In Vitruvius’ opinion, the only way to appreciate artistic excellence in his day was ‘by the use of colours and the brave show they make.’
This could explain why Vitruvius, and Pliny the Elder after him, left us with such a detailed catalogue of the pigments available to the Roman palette. Natural or artificial, readily available or rare, our knowledge of these pigments is now supplemented by analysis of modern technology, enabling us to fully appreciate the full range available to Roman artists- and how they made us of them to create colour and tone in wall paintings.
Red Pigments in Rome
Red was one of the most popular colours in Roman wall art, finding itself applied to street walls as well as frescos. Pliny and Vitruvius describe a variety of red pigments. Some were standard parts of the artist’s palette while others were so costly the patron had to specially supply them.
First, there were the abundant and cheap red pigments.These were mainly naturally occurring ‘red earths’, ‘found in abundance in many places.’ Such colours were generally red iron ore based and included ruddle, red ochre and hematite.
Modern analysis using electronic spectroscopy has proven these to be the most prolific red pigments in use. Siddall, in her study of Pompeian frescos, also found that the Romans used madder root and crushed insects. But the most desirable red was the artificially-produced vermilion. It was also the most expensive-16 times more costly than red ochre, which cost only 2 denarii per Roman pound.
The Romans made vermillion from cinnabar, a naturally occurring mineral ore. To produce the pigment, which was one of the purest, brightest reds, they washed and heated the ore, most famously in factories in Rome near the temples of Flora and Quirinus.
But vermilion was unstable, turning black in sunlight, which was why Vitruvius warned against its use for ‘open apartments such as peristyles or exedrae.’ As a solution for those determined to use the colour outdoors, he suggested treating the completed paintwork with a mixture of melted pontic wax and oil buffed with linen cloths and sealed with candle wax.
But despite the emphasis on the desirability of cinnabar based vermillion, modern analysis has proven that it was rarely used in its pure form. Instead, the Romans mixed cinnabar with other pigments- to cut the expense and possibly stabilize the colour. Vitruvius mentions lime as one such additive but Edreira, et al, and Siddall have shown that the Romans cut pure cinnabar with the cheaper red oxide based pigments such as hematite and red ochre.
Ochre/Yellow Pigments For Roman Artists
Yellows and browns were also staples of the Roman artist, forming backgrounds to wall paintings and also providing flesh tones to figures. Yellow ochre- made from a clay containing yellow iron oxide- was the most commonly used yellow pigment, according to both historical sources and modern studies.
But other yellow pigments were available. Vitruvius mentions orpiment, an arsenic based ore, which gave a clear, bright yellow paint. Spectroscopy has identified others. Mazzocchin, et al, have identified Limonite, a yellow iron ore as pigment used in Italian villas. The various studies have also revealed that different shades of yellow could be achieved by blending with other colour pigments.