Scientists Say Lead in Ink Could Crack Herculaneum’s Burnt Scrolls—So They Baked a Fake One

More than 2,000 years after Mount Vesuvius buried a library in Herculaneum under ash and preserved the only known intact library from antiquity, scientists are testing a new imaging method to read its brittle, carbonized husks. Because the ancient scrolls are almost impossible to unroll without reducing them to black dust, researchers are turning their attention to the chemical composition of the ink itself.

Replicating an Ancient Disaster in a High-Temperature Furnace

To determine whether leaded ink could be detected inside a charred document, Douglas Seiler, an affiliate of Berkeley SETI, built his own physical simulation of the ancient catastrophe. He sourced traditional papyrus and reed pens from Egypt alongside lampblack ink from Japan, and then hired high school students to write lines from Star Wars, the Bible, and the television show The Outer Limits onto the sheets.

After rolling up the inscribed papyrus, Seiler placed it inside a container within a high-temperature, nearly oxygen-free furnace and baked it until it carbonized into a brittle cylinder that mirrored the artifacts housed in Italy. The eruption, which also buried nearby Pompeii, preserved for posterity the only known intact library from antiquity. This experimental model allowed the team to test imaging techniques without risking damage to priceless historical artifacts.

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How Lead Content Creates an X-Ray Signature

In a study published in the journal PLOS ONE, the research team reports that minuscule amounts of lead in ink absorb up to 25 times more X-rays than the surrounding charred papyrus. When scanned via X-ray computed tomography (CT), this stark difference in density makes the written characters stand out brightly in a 3D computer model. A 3D model of a burned scroll is still illegible, however, and so the team used a computer algorithm to virtually unroll the scroll and display the text.

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Scholars have historically struggled to read the collection because both the papyrus and the ink are carbon-based, creating a severe contrast problem. With lead in the ink, you would get a huge friggin’ signature, so you really need to be looking for scrolls with lead in them, Douglas Seiler said. We’re relatively certain that if they start searching for lead, or they let us search for lead, it will help this whole process. This is the Holy Grail.

The researchers also demonstrated that an inexpensive handheld X-ray fluorescence scanner can easily detect leaded ink in a burned scroll, providing a straightforward screening method to identify which artifacts are best suited for detailed X-ray CT virtual unrolling.

The Stakes for Classical Literature and Philosophy

Discovered in 1752 at the Villa of the Papyri, the roughly 1,800 surviving scrolls and fragments represent the only known intact library from antiquity, currently housed in Italy, France and England. Many of the texts that have been successfully unrolled over the centuries contain previously unknown works by the Epicurean philosopher Philodemus, who lived in Herculaneum a century before the Vesuvius eruption.

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While early attempts to physically unroll the scrolls following their discovery in 1752 largely reduced them to piles of ash—prompting Italian authorities to call a halt to such efforts—recent technological advances in virtual unrolling have opened new possibilities. Although researchers have virtually unrolled and read a few Herculaneum scrolls without looking for lead, the new findings suggest that targeting leaded ink could significantly accelerate future decoding efforts. Leah Packard-Grams, a papyrologist at the University of California, Berkeley, who consulted for the research, emphasized the magnitude of the ongoing work, stating that the value in this project is practically unquantifiable.