Book detectives solve puzzles of yesteryear

A mysterious piece of parchment lies in a glass case at the Gunnerus Library at the Norwegian University of Science and Technology (NTNU), carefully protected from sunlight and heat. The document isn't complete. It is cut in half, and is believed to be part of a book. The text is in Latin, written with illuminated letters in a gothic style. One of the letters is much larger than the rest, and is inlaid with gold foil.

The library has no information about the book aside from this bit of parchment. They don't know if the rest of the page is somewhere else in the world, or if the rest of the book even exists.

According to Victoria Juhlin, a conservator at the library, this mysterious orphan page is most likely part of a church book from the 1400s, made by monks.

"One of the challenges of a project like this is studying the document as closely as possible. Documents like this are very sensitive and fragile, and should ideally not be touched or exposed to light. Throughout history, many methods have been used that cause irreparable damage to manuscripts like this one," Juhlin says.

Working in stations

Making books like the one this piece of parchment came from was a time-consuming process in which a lot of people were involved. Skins from sheep, calves or goats were treated with a lime solution to dissolve the fat and get rid of residual hair and tissue.

The skins were then dried and stretched on a frame, before finally being rubbed with chalk and pumice. To make each individual page, the monks worked in stations. One monk was responsible for preparing the text, while another focused on illuminating the letters, and others worked on the drawings that accompanied the stories.

To find out more about this piece of parchment, the Gunnerus Library has been working with Emilio Catelli and a team of researchers from NTNU's Department of Chemistry.

Catelli is a PhD candidate at the Department of Chemistry, and is studying this manuscript and similar ones as part of his doctorate work. He is writing is dissertation with PhD candidate Kidane Fanta Gebremariam, also from NTNU's Department of Chemistry.

Rarely used on manuscripts

Catelli has primarily been using a technique called hyperspectral imaging to determine the chemical composition of the pigments used in manuscripts.

Early in the process, he contacted his supervisor Lise Lyngsnes Rande, who is a professor of biomedical optics and photonics at the university. She was one of the first researchers to use hyperspectral imaging for medical diagnostics, among other things to characterize bruises.

Hyperspectral imaging has also been used to closely examine other forms of art, primarily paintings. In 2012, "The Scream" by Edvard Munch was analysed using this method. However, it has not been used to look at old manuscripts.

"The technique is quite effective for examining old manuscripts, and yields much better results than other methods. Whole pages can be scanned and analysed in a matter of minutes. Fragile documents are also protected from marks and rough handling," says Catelli.

Differentiates between 160 colours

Hyperspectral imaging uses a hyperspectral camera to scan the document. Advanced cameras can differentiate between 160 colours, and have 1600 pixel sensors.

These cameras are good for studying art at a macro level, where details and colour pigments that were previously impossible to see are now made visible because of the high spectral resolution.

Cultural CSI agent

"Hyperspectral imaging turns out to be very useful for studying art, with the researcher acting as a sort of cultural CSI agent. The method was originally developed for military use, specifically aerial observation. The method is also used in medical diagnostics, food science, archeology and environmental observation," says Lyngsnes Randeberg.

According to Juhlin, the use of technology to study art has skyrocketed over the last 10-15 years, with methods that are not only much more accurate than were previously available, but also much more gentle with fragile documents. In the worst case, researchers used to cut into artefacts to study them, Juhlin explains.

New finds

Manuscripts like these need to be properly preserved to not be destroyed over time. It is important that they are not exposed to direct sunlight or high temperature. Knowing the different pigments that a piece of parchment contains, and what binders are used on it can also help conservators correctly preserve documents.

The Gunnerus Library staffers do not know much about the chemical makeup of this piece of parchment, but Catelli is helping them. In addition, he will be able to see if the parchment has been affected by any chemical reactions over time, to make sure that it is treated accordingly.

"So far, the examination that I've done has given us a lot of new information, but I need to verify it before I can say anything specific about the manuscript," Catelli says.

Diving deep

One of the shelves at the Gunnerus Library is home to a small book with a brown spine. The book used to belong to Sigrid Undset, and is of a religious nature.

Catelli is working on analysing the book's pages, and with the modern technology, he is able to look at the manuscript in a very different way. He is diving deep into the book's secrets, and soon he will be able to share its knowledge with the world