The Digital Revolution
The historic digitalization is on the rise thanks to various projects across Europe. These projects collect enormous digital libraries of 3D models, from archaeological objects to large buildings. One of the most overlooked items for digitization are often written texts, specifically those in poor condition.
In particular, papyrus is one of the most fragile materials that exist, even more so if they have been exposed to external factors such as carbonization. In these cases, it becomes impossible to read them with traditional techniques, leaving their secrets hidden from human eyes. With advances in technology, this mystery is getting closer to being solved without the need to manipulate the manuscripts.
From Vesuvius to the present
An example of this technique can be found in the Herculaneum papyri. These papyri belonged to a library within an estate in the Bay of Naples, filled with texts ranging from philosophers' writings to poetry. Unfortunately, it was located near the famous volcano of Vesuvius, which erupted in 79 AD burying Pompeii and its neighboring city, Herculaneum. Later, during excavations in 1752, approximately 1,800 carbonized papyri were found and preserved thanks to layers of hardened rock. Most of these papyri contain Epicurean texts. Some could be manually unrolled, but others remain very fragile. One of the main problems is ink composition, which makes it difficult to read the words (Jaggard, V., 2015). However, today with digital technology, this hidden information can be recovered.
It should be noted that many techniques are not suitable for all types of papyri. One of the most traditional methods is computerized tomography, which emits X-rays to look for patterns created by radiation absorption. This method is the most common, originating in hospitals (Stromer et al., 2018). In the case of the Herculaneum papyri, a new technique called X-ray phase-contrast tomography was used at the European Synchrotron Radiation Facility (Grenoble, France). This method selects contrast changes in layers within objects instead of looking for patterns of absorbed radiation (Parker et al., 2019, p.6-7).
This new technique was invented by Brent Seales, a professor and computational science researcher at the University of Kentucky. He has been restoring biblical texts for over twenty years. One of his major works was recovering text from the En-Gedi scroll, which contained chapters of Leviticus in the Hebrew Bible, making it its oldest copy found to date. Additionally, he is involved in the Herculaneum papyri project (EduceLab, s.f.).
The success of Seales' technique (Fig. 1) depends on ink type and density. The most legible ink is made from iron, even after erasure or overwriting processes. This type of ink began to be used in the third century AD. Unfortunately, these papyri are from 79 AD, thus predating the standardization of this ink. Other types of ink include malachite ink or purple ink, but the ink used on these papyri was a mixture of water, carbon, and lead. Therefore, the ink does not sit on fiber layers of the parchment but is absorbed by the fabric, making it difficult to detect with traditional methods (Stromer et al., 2018; Marchant, J., 2018).
With the Synchrotron on the side of scientists, Seales' new X-ray technique, and the small amount of lead in the ink, deciphering is possible. The tiny amount of lead emits a characteristic electromagnetic radiation that helped detect the first letter of one of the papyri, a "C" (Fig. 2), which so far is the only letter detected (Parker et al., 2019, p.10). Currently, there is an international contest with monetary rewards initiated by researchers to solve the mystery of two carbonized Herculaneum papyri, including the one mentioned.
The main disadvantage of Seales' technique is the acceleration of the aging process of fibers during scanning. Not only that, but one must also consider the position of the object being scanned to acquire as much information as possible. Another method that could have been used without accelerating fiber aging is the acquisition of three-dimensional images by terahertz imaging. This technique is easier to transport since it requires only a scanner and a powerful computer, allowing its use anywhere without continuous visits to radiation centers. However, this method has limited penetration into objects.
Once the scanning data is obtained, what's next?
How do we go from data to being able to «read»?
After scanning comes the real challenge of this method: extracting the parchment since it is curled and tightly rolled. This is usually done with corresponding software (3DCNN), which uses digital mapping to unroll the parchment, orient letters, and align scans (Parker et al., 2019, p.7). Finally, the extracted information is mapped in 2D. In one of the Herculaneum papyri, two sequences of uppercase Greek letters have been visualized. The resulting scans demonstrate a promising future for complex parchment work.
Conclusions
In conclusion, new advancements in digitalization give us hope that research on such documents will advance, allowing forgotten information to be revealed. There is much left to discover and it's necessary to establish guidelines for analysis based on various ink and material variables. What is clear is that this would improve accessibility to heritage and open doors to virtual visits and educational applications (Aniwaa., s.f.). In the near future, perhaps all we will need to do is press a button to see what was written directly, but until then, there exists an open-source method of code and calculations available for everyone.
Bibliography
Aniwaa Team (2020, August 5). 3D printing and 3D scanning for archeology and museums. (Accessed June 1, 2023) https://www.aniwaa.com/guide/3d-printers/3d-printing-for-archeology-and-museology/
EduceLab. A Digital Restoration Initiative (2023). https://www2.cs.uky.edu/dri/
EduceLab. A Digital Restoration Initiative (s.f). Faculty. W. Brent Seales Ph.D. https://www.engr.uky.edu/directory/seales-brent
Jaggard, V. (2015). Ancient Scrolls Blackened by Vesuvius Are Readable at Last. Smithsonian. (Accessed June 5, 2023) https://www.smithsonianmag.com/history/ancient-scrolls-blackened-vesuvius-are-readable-last-herculaneum-papyri-180953950/
Marchant, J. (2018). Buried by the Ash of Vesuvius, These Scrolls Are Being Read for the First Time in Millennia. Smithsonian. (Accessed June 5, 2023) https://www.smithsonianmag.com/history/buried-ash-vesuvius-scrolls-are-being-read-new-xray-technique-180969358/
Parker, C. S., Parsons, S., Bandy, J., Chapman, C., Coppens, F., Seales, W.B., (2019) From invisibility to readability: Recovering the ink of Herculaneum. PLoS ONE 14(5): e0215775. https://doi.org/10.1371/journal.pone.0215775
Stromer, D., Christlein, V., Martindale, C., Zippert, P., Haltenberger, E., Hausotte, T., Maier, A, (2018). Browsing through sealed historical manuscripts by using 3-D computed tomography with low-brilliance X-ray sources. Sci Rep8, 15335. https://doi.org/10.1038/s41598-018-33685-4
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