Berkeley Scientists Burn Modern Papyrus Replicas to Help Decode Vesuvius Scrolls

To investigate how writing might be recovered from carbonised papyrus scrolls buried by the eruption of Mount Vesuvius, scientists at the University of California, Berkeley, created modern papyrus replicas and set them on fire. Published in the journal PLOS ONE, the study details how researchers prepared contemporary scrolls using ink containing different amounts of lead before carbonising them in a low-oxygen environment. The resulting experiments demonstrated that leaded ink could stand out dramatically in X-ray scans, offering a promising method to identify ancient scrolls whose hidden writing may be recoverable.

The experiment addresses one of archaeology's most challenging collections: the Herculaneum scrolls. When Mount Vesuvius erupted in 79 CE, volcanic material buried an ancient Roman town near modern Naples, Italy, including a library containing over a thousand papyrus scrolls. The extreme heat carbonised the texts, turning them into fragile, blackened objects. While the process preserved the manuscripts, it created a severe obstacle for researchers, as physically opening the scrolls can cause irreversible damage or destroy them entirely. As the only known intact library from antiquity, the collection holds texts that have never been read in the modern era, prompting ongoing efforts to look inside without unrolling them.

A primary obstacle in reading the ancient material is that ordinary carbon-based ink and carbonised papyrus share similar visual properties under X-ray techniques. Because both contain carbon, the contrast between the written letters and the surrounding papyrus is extremely weak, making it difficult for X-ray computed tomography (CT) scans to distinguish individual characters. To overcome this limitation, the Berkeley-led team explored whether lead could provide a stronger signal. Because lead is much denser than carbonised papyrus, it interacts differently with X-rays. The researchers found that leaded ink absorbed up to 25 times more X-rays than the surrounding charred papyrus, causing the handwritten letters to stand out clearly.

To conduct the test, researcher Douglas Seiler prepared papyrus, reed pens, and ink containing varying concentrations of lead. High school students then wrote passages on the modern papyrus, including lines from Star Wars, Bible verses, and a quotation from the television series The Outer Limits. Researchers rolled the papyrus into scrolls, placed them in a low-oxygen container, and heated them in a high-temperature furnace to replicate the physical condition of the ancient Herculaneum material. Using model scrolls allowed scientists to experiment, scan, and process the material repeatedly without risking irreplaceable historical artefacts.

Following carbonisation, the experimental scrolls were examined using X-ray CT and X-ray fluorescence techniques. The tests revealed that lead concentrations as low as 25 micrograms per square centimetre could be successfully detected. According to the researchers, this suggests that scientists could potentially use inexpensive handheld X-ray fluorescence scanners as an initial screening tool to identify scrolls containing leaded ink before prioritizing them for detailed X-ray CT imaging.

Detecting letters is only part of the challenge, as a scroll consists of tightly packed layers of papyrus that must be separated computationally. The team tested software originally developed to map the internal layers of lithium-ion batteries, adapting the programme to follow the complex geometry of a carbonised scroll and produce a flat, unfolded representation of its surface. Because the team already knew the exact text written on the experimental scroll, they could compare the original writing with the computer-generated reconstruction to evaluate the effectiveness of the software.

The research does not mean that scientists have already read previously inaccessible Herculaneum scrolls using the technique, but it provides a viable method for identifying which specimens might be easier to decipher. While previous breakthroughs have relied on advanced artificial intelligence and machine-learning systems, the new lead-detection approach could provide a powerful supplementary signal when lead is present, ultimately helping researchers recover text lost since antiquity without opening fragile originals.