When Mount Vesuvius erupted in 79 CE, volcanic gas and ash buried a library of papyrus scrolls in the ancient city of Herculaneum, carbonizing the documents. Nearly 2 millennia later, those scrolls remain too brittle to open to reveal their hidden contents. Scientists have tried to X-ray scan the unopened scrolls and to use computational algorithms to extract the text. Still, the narrow contrast between the ink and the paper has made it hard to reconstruct the text reliably. Researchers at the University of California, Berkeley (UCB), and the National Institute of Standards and Technology now report a two-step method that overcomes this constraint. They demonstrated the technique on model scrolls built in the lab (PLOS One 2026, DOI: 10.1371/journal.pone.0353485).
The contrast problem arises because the ink and papyrus are both carbon based, so X-rays pass through each material at nearly the same rate. Study leader Douglas Seiler of UCB and his team realized that lead absorbs X-rays far more strongly than papyrus does, and a scroll whose ink contained lead would produce images in which the letters stand out against the surrounding papyrus.
Not all ancient inks contained lead. “There was not a single recipe for ink,” says Vito Mocella, a researcher at the National Research Council of Italy who was not involved in the study. “But we found that at least some of the Herculaneum scrolls contained lead.”
So Seiler’s team developed a triage approach that starts by testing for lead. To search for the metal, the researchers screen each scroll with a handheld X-ray fluorescence (XRF) instrument. XRF identifies elements by shining X-rays onto a surface and recording the energies of the fluorescent X-rays the surface atoms emit. If XRF detects lead, the team sends the scrolls for further imaging to distinguish the letters from the papyrus.
For the second step of the test, the team made model scrolls from modern Egyptian papyrus, inscribed them with a stylus using carbon-black ink—a soot-based pigment commonly used in ancient inks—spiked with varying amounts of lead, and carbonized the scrolls in a kiln. They tested samples with lead surface concentrations of 200 µg/cm2 down to 25, which is lower than the lowest concentration found in the ancient fragments. The handheld XRF instrument returned a lead signal from every sample.
Researchers made models of ancient scrolls (left) and carbonized them in a kiln(right) to mimic the scrolls that were charred and buried in Herculaneum when Mount Vesuvius erupted in 79 CE. Credit:
Douglas Seiler
The researchers then perform X-ray tomography on a carbonized model scroll, collecting images from multiple angles to build a 3D picture of the writing inscribed in the scroll. Custom software virtually unrolls the data, making the lead-marked words legible.
Though the approach has limits, it offers a viable path toward analyzing the 2,000-year-old scrolls. To work through the large collection, researchers would need to devise a way to scan each scroll automatically, which would involve repositioning the detector at multiple points along the length of an unopened scroll. Another challenge is that the model scrolls do not capture the full damage of the originals, Mocella says. The ash and pressure from the eruption shattered and distorted the real scrolls far more than seen in the kiln-fired models. “This study can only be seen as a first step, but it is a good workflow,” Mocella says.
In addition, the process does not work for scrolls written in lead-free ink. But Mocella’s XRF work on Herculaneum fragments has uncovered metals other than lead in these ancient inks. “I would try to look for these other metals in the scans as well,” he says.
