Hundreds of papyrus scrolls carbonized during Mount Vesuvius’ eruption in AD 79 remain unread inside Italy’s National Library of Naples. Known as the Herculaneum scrolls, most are too fragile to withstand physical unrolling.

Researchers and citizen scientists are instead turning to X-ray technology, virtual unrolling methods and advanced artificial intelligence. Their aim is to recover writings concealed inside artifacts that now resemble solid pieces of charcoal.

A study published September 16 in the scientific journal PLOS One may offer a way to identify promising scrolls before attempting that demanding process. Researchers recreated papyri using inks with different amounts of lead and found that X-ray imaging detected lead containing ink more easily than nonmetallic ink.

Only a few authentic Herculaneum scrolls have been virtually unrolled so far. The findings could help researchers determine which unopened scrolls are the strongest candidates for noninvasive scanning and deciphering.

Lead author Douglas Seiler, a research volunteer with the University of California, Berkeley, described the central imaging challenge. “It’s just carbon, and that’s what the problem has been in reading these things. The ink is made from soot.”

Without metal, artificial intelligence must distinguish ink from papyrus when both materials appear as carbon. Seiler described the difficulty as “dark carbon on dark carbon,” while lead produces a much clearer signal in X-ray scans.

The next step is to examine genuine Herculaneum scrolls and determine what percentage contain lead. “If they took these scrolls one by one to a facility, they could find out in a matter of minutes whether or not they had lead in them,” Seiler said. “A lead signal is very strong.”

One complete scroll and passages from several others have been deciphered to date, largely through the Vesuvius Challenge. Launched in 2023, the project offers cash prizes to researchers who successfully decode the ancient documents.

Much of that work has focused on scrolls in comparatively good physical condition, particularly those that remain symmetrical. More than 600 unopened scrolls exist, however, and many examples in the Naples library have been crushed or reduced to fragments.

For those badly damaged artifacts, Seiler said scanning for lead should come before virtual unrolling and text analysis. A strong metallic signal could make the writing easier for imaging systems and artificial intelligence to identify.

Computer scientist Brent Seales, cocreator of the Vesuvius Challenge, first detected metallic ink in a Herculaneum scroll in 2009 while studying it at the University of Kentucky in Lexington. A 2016 study later identified lead in two additional fragmented scrolls and suggested it had been deliberately added to the ink.

To investigate whether that lead could assist decoding, Seiler’s team made multiple replica scrolls from Egyptian papyrus and carbon ink resembling ink used in Pompeii. Their written passages included material from the Bible, Alfred Hitchcock movie scripts and the television program “The Outer Limits.”

The researchers rolled the replicas and carbonized them inside a furnace using high temperatures and little oxygen. This process was designed to mimic the conditions that preserved the original documents during the eruption of Mount Vesuvius.

The replica scrolls then went to the National Institute of Standards and Technology in Gaithersburg, Maryland. Researchers used X-ray tomography and virtual unrolling techniques to reconstruct them, identifying readable writing at every tested lead concentration level.

“In fact, they picked up the images much, much better than we thought,” Seiler said. The journal described the results as a new opportunity to read some of the more complicated Herculaneum scrolls.

The study authors also wrote that their recreation method could provide additional training material for artificial intelligence and potentially improve algorithms used to read ancient texts. Seales said researchers have observed wide variation in ink formulations, including scrolls with greater metal concentrations.

However, Seales said the variation and generally low concentrations suggest that metal may have entered the ink accidentally rather than serving as a standard ingredient. He also stressed that scrolls without metallic ink can still be deciphered through virtual unwrapping and analytical artificial intelligence.

“Somehow the scrolls found a way to survive, and we have found a way to redeem them,” Seales said. “If their revelation is helped by accidental chemistry like lead that found its way into the ink, we can add another miracle to a string of them needed to bring those words back from the brink.”