Earth & Conservation

X-Ray Reveals Ancient Roman Portrait Covered in Mt. Vesuvius Ash

The artistry behind an early Roman portrait that went virtually unnoticed for centuries has been uncovered by a new, non-invasive X-ray fluorescence device.

An iron element map (right) made with new X-ray technology reveals the underlying craftsmanship hidden beneath a damaged portrait of a Roman woman (left). | Roberto Alberti
An iron element map (right) made with new X-ray technology reveals the underlying craftsmanship hidden beneath a damaged portrait of a Roman woman (left). | Roberto Alberti

For centuries, the ancient Roman resort town of Herculaneum was buried under 66 feet of volcanic material. The city on the Italian coast, along with nearby Pompeii, was destroyed during an eruption of Mount Vesuvius in 79 AD. Excavations in the mid-19th century uncovered much of Herculaneum, including its large “House of the Mosaic Atrium,” but an ancient painting in the house went almost unnoticed, until now.

A newly developed portable macro X-ray fluorescence instrument, ELIO by XGLab SRL, revealed the Roman woman in the portrait that has been subjected to molten lava, volcanic ash, grime, salt, and humidity over the years. As if that weren’t rough treatment enough, its exposure since it was excavated 70 years ago has caused much of it to deteriorate.

The portable X-ray instrument was brought directly to the site at Herculaneum, where the noninvasive analysis of the mid-1st century AD painting occurred.

“As far as we know, this is the first study of an ancient Roman wall painting — or any other historical wall painting — in situ, in its original setting,” Eleonora Del Federico, a professor of chemistry at the Pratt Institute who studies artists’ materials and conservation, told Seeker. “The technique is fairly new, and has been used for studies at museums on Rembrandts, Picassos and Van Goghs, among others.”

The ELIO device scanning the Roman portrait within the House of the Mosaic Atrium at Herculaneum. | Eleonora Del Federico

While ELIO works best at just over a half an inch away from an artwork’s surface, the instrument never actually touches a painting. It is not difficult to operate, but ELIO is not cheap and the data analysis and interpretation of the results it provides require specialized training.

Del Federico, who conducted this latest research in conjunction with the Herculaneum Conservation Project, will present her findings today at the 254th National Meeting & Exposition of the American Chemical Society in Washington, DC.

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Her analysis revealed that an artist created a sketch of the young woman with an iron-based pigment, and then put highlighting around the woman’s eyes in the sketch with a lead pigment. High levels of potassium in the woman’s cheeks in the artwork suggest that a green Earth pigment was used as an underpainting to help create a flesh-toned color.

“We were very surprised at the complexity and sophistication of the painting technique, the use of color, mixture of pigments and layering,” Del Federico said.

Images of the early Roman painting showing the various elements revealed by the macro X-ray fluorescence instrument.

She explained that the painting method actually involved two primary techniques. The first, known as fresco, involved applying pigments on a wet surface of lime mortar, which consists of a mixture of calcium hydroxide and sand and/or pumice stone. The second, called secco, involved applying pigments with organic binders to the surface once the lime mortar had set. 

Together, these methods were used to contour the portrait and to give realistic-looking volume to the subject’s face, cheeks and nose.

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ELIO allowed Del Federico to create an “iron map” highlighting the woman’s primary features.

“When we look at the map of iron atoms, it reveals a beautiful young woman caught in a moment of deep thought,” she said. “You can always feel her presence, talk to her and feel her humanity, at least for me. She was gone by the years of exposure to the elements, and now she is back to life.”

The portrait is not signed, so the artist, for now, remains a mystery. Intriguingly, a similar portrait known as “Saffo” is on exhibit at the National Archaeological Museum of Naples. It is possible that both portraits were created by an artist who was given the honorary title “pictor imaginarius.” Many painters worked in early Roman towns, but the “pictor imaginarius” was among the most skilled, and would be brought in to tackle prominent wall areas requiring greater expertise.

A sketch of the woman in the early Roman painting created with an iron-based pigment. | Roberto Alberti, Eleonora Del Federico

As for who the woman was in the Herculaneum portrait, she remains a mystery for now, too. Del Federico said that she is possibly wearing a tiara. The House of the Mosaic Atrium “was indeed a well-to-do household, but not necessarily aristocratic.”

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Roger Ling, a professor of classical art and archaeology at the University of Manchester, believes that a portrait such as this functioned as “a symbol of aristocratic luxury by which householders liked to surround themselves.”

Del Federico added, “A good quality wall painting was a sign of status.”

In collaboration with Bernhard Blümich of Aachen University, she is currently studying the painting techniques of artworks from early homes of different social standings, in order to correlate the methods used with the funds that were available by the house dwellers.

The portrait of the Roman woman remains in the house at Herculaneum. The room where it is located can be viewed as a 360-degree panorama. Similar interactive images provide a virtual tour of the ancient city.

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