NIST: lead-containing ink makes a carbonised scroll readable in X-ray tomography — a laboratory model of a Herculaneum scroll and a handheld XRF analyser for pre-screening scrolls
On 17 September 2026 NIST described a study published the day before in PLOS ONE: researchers made a laboratory model of a carbonised papyrus scroll written with ink containing a lead salt and read it by virtually unrolling the image from a laboratory-grade X-ray tomography system. A handheld XRF device detected lead in the ink even after carbonisation.
- The scroll was made from modern Egyptian papyrus; carbon ink was mixed with varying concentrations of lead sulfate, which experts believe resembles the composition of Roman-era inks. The replicas were placed in partially sealed steel containers and carbonised in a high-temperature furnace with little or no oxygen, imitating the conditions in which the eruption of Vesuvius in 79 CE carbonised the Herculaneum scroll library.
- To unroll the image, NIST adapted an algorithm developed there earlier to virtually unroll the layers of a cylindrical lithium-ion battery from tomographic images. The scroll, however, is squashed and some layers are fused, so it cannot be treated as a perfect spiral. Only the maker of the replica knew the text, which allowed the reading to be checked against ground truth; the modified algorithm deciphered the text within days.
- Scrolls written in pure carbon ink are the hardest, because X-rays barely distinguish the carbon of the ink from the carbon of the charred papyrus, whereas lead interacts strongly with X-rays and provides contrast. The authors propose the model as a source of ground-truth datasets with inks of different composition for developing and validating text-detection algorithms, and handheld XRF spectrometry as a practical, non-destructive screening method for scrolls likely to contain lead ink and therefore more likely to be read.
- The authors consider this the first confirmed proof of concept that the presence of lead in Herculaneum scrolls would greatly increase the probability of successful reading. The leaders of the Vesuvius Challenge are aware of the NIST study but have not yet decided whether to incorporate it. NIST researchers hope that further work with artificial scrolls will help build better algorithms for reading the real ones.