Berkeley SETI experiment shows lead ink enables reading of carbonized Herculaneum scrolls

September 26, 2026 at 07:32 PM2 min

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Researchers at Berkeley SETI burned papyrus scrolls written with lead-based ink to test whether X-ray tomography could reveal text on carbonized ancient manuscripts. The experiment, published Sept. 16 in PLOS ONE, found that lead in ink absorbs up to 25 times more X-rays than surrounding burned papyrus, making characters detectable. The method could help read the Herculaneum scrolls, the only intact library surviving from antiquity, without unrolling them.

Key Facts

The experiment burned papyrus scrolls written with passages from Star Wars, the Bible, and a quote from The Outer Limits.
Lead in ink absorbed up to 25 times more X-rays than the surrounding carbonized papyrus.
A handheld X-ray fluorescence scanner detected lead-based ink in burned scrolls, offering a screening method.
The Herculaneum collection, carbonized by the eruption of Mount Vesuvius in 79 C.E., is the only intact library surviving from antiquity.

Experimental Setup

Douglas Seiler, an affiliate of Berkeley SETI, obtained papyrus and reed pens from Egypt and traditional lampblack ink from Japan. He paid high school students to write on the papyrus using passages from Star Wars, the Bible, and a quote from the 1960s science fiction television show The Outer Limits. Seiler then rolled up the papyrus, sealed it in a container, and burned it in a high-temperature furnace until it was thoroughly carbonized. The experiment mimicked the catastrophe that occurred in Herculaneum in 79 C.E., when volcanic ash from Mount Vesuvius carbonized more than a thousand papyrus scrolls in a local library.

X-Ray Detection Results

In a paper published Sept. 16 in PLOS ONE, Seiler and collaborators including several Berkeley experts reported that the strategy works in their experimental scrolls. Even extremely small amounts of lead made written characters detectable with X-ray tomography, also called X-ray CT. Lead absorbed as much as 25 times more X-rays than the burned papyrus around it, causing the writing to stand out dramatically. Seiler said, "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." The researchers also found that a relatively inexpensive handheld X-ray fluorescence scanner could readily detect lead-based ink in a burned scroll, providing a straightforward way to screen ancient scrolls first.