An analysis of the material in the books helps to turn the object into a historical context and guides conservatives in future restoration work.
A picture can be worth a thousand words, but drawing numerous images along the electromagnetic spectrum of a work can tell a rich story about the original creation and degradation of historical objects over time. Researchers have recently demonstrated how this is possible by using several complementary imaging techniques to examine a Jewish parchment book non-invasively. The results were published in the journal Boundaries in materials.
A group of scientists from the National Research and Development Institute of Optoelectronics in Romania have released details about the original manuscript materials and production techniques using various spectroscopic instruments. These specialized cameras and devices capture images that the human eye cannot normally see.
“The aim of the study … was to understand what time has brought to the facility, how it has been degraded, and what would be the best approach for the future conservation process,” said co-author Dr. Luminita Ghervase explained. paper and research scientist at the institute.
The manuscript examined by the group is a poorly preserved but sacred book with several chapters from the Hebrew Bible book of Esther. A work from a particular collection was little known about the testing or history of the object.
“The application of complementary research methods can shed light on the unknown history of such an object,” Ghervase said. “For several years now, non-invasive, non-destructive research methods have been the first choice when researching cultural heritage sites to avoid damaging an object in order to comply with one of the basic rules of conservation practice.”
One of the more common imaging methods is multispectral imaging, which involves scanning an object within certain parts of the electromagnetic spectrum. Such images may show details that are not otherwise visible due to the wear of the manuscript. For example, different ultraviolet regimes have revealed a dark spot that can point to a correction using an organic material such as resin on the rule, because the dot absorbs ultraviolet rays strongly.
A related technique, hyperspectral imaging, was used to determine the material basis of the ink on aged parchment. Scientists have identified two different types of ink, which is another indication that one has previously tried to repair the object. They also used a computer algorithm to help characterize the spectral signals of individual pixels to discriminate materials – a promising method for reconstructing the text itself.
“The algorithm used to classify materials can be used to identify complex traces to extract the original shape of the letters,” he said.
The team used a imaging technique called x-ray fluorescence (XRF), which can identify the types of chemicals used in both ink and parchment production. XRF, for example, has often found rich concentrations of a chemical associated with the bleaching process, but this is another indication of past recovery work. Finally, the scientists used a Fourier-transform infrared (FTIR) spectrometer to identify other chemicals present using an infrared light source to measure absorption. Specifically, the FTIR analysis provided an in-depth insight into, among other things, the degree of deterioration of collagen in shoots made from animal skin.
Using these different imaging techniques to break up parchment can help conservatives get closer to the object’s original condition by identifying the materials used to create it.
Ghervase said, “They can wisely decide if any inappropriate material is being used and they don’t want to remove such materials.” “In addition, restorers can select the most appropriate materials for the restoration and protection of the facility, excluding possible non-conforming materials.”
Reference: “Application of Spectroscopic and Hyperspectral Imaging Methods for Rapid and Non-Distortion Study of Jewish Ritual Parchment” by Ioana Maria Cortea, Luminiţa Ghervase, Lucian Ratoiu and Roxana Rădvan, 18 December 2020, Boundaries in materials.
DOI: 10.3389 / fmats.2020.601339