Technique based on LED multispectral imaging and multivariate analysis for monitoring the conservation state of the Dead Sea Scrolls.

The aim of this project is the development of a noninvasive technique based on LED multispectral imaging (MSI) for monitoring the conservation state of the Dead Sea Scrolls (DSS) collection. It is well-known that changes in the parchment reflectance drive the transition of the scrolls from legible to illegible. Capitalizing on this fact, we will use spectral imaging to detect changes in the reflectance before they become visible to the human eye. The technique uses multivariate analysis and statistical process control theory. The present study was carried out on a "sample" parchment of calfskin. The monitoring of the surface of a commercial modern parchment aged consecutively for 2 h and 6 h at 80 °C and 50% relative humidity (ASTM) was performed at the Imaging Lab of the Library of Congress (Washington, DC, U.S.A.). MSI is here carried out in the vis-NIR range limited to 1 µm, with a number of bands of 13 and bandwidths that range from about 10 nm in UV to 40 nm in IR. Results showed that we could detect and locate changing pixels, on the basis of reflectance changes, after only a few "hours" of aging.

Direct Analysis in Real Time Mass Spectrometry for the Nondestructive Investigation of Conservation Treatments of Cultural Heritage.

Today the long-term conservation of cultural heritage is a big challenge: often the artworks were subjected to unknown interventions, which eventually were found to be harmful. The noninvasive investigation of the conservation treatments to which they were subjected to is a crucial step in order to undertake the best conservation strategies. We describe here the preliminary results on a quick and direct method for the nondestructive identification of the various interventions of parchment by means of direct analysis in real time (DART) ionization and high-resolution time-of-flight mass spectrometry and chemometrics. The method has been developed for the noninvasive analysis of the Dead Sea Scrolls, one of the most important archaeological discoveries of the 20th century. In this study castor oil and glycerol parchment treatments, prepared on new parchment specimens, were investigated in order to evaluate two different types of operations. The method was able to identify both treatments. In order to investigate the effect of the ion source temperature on the mass spectra, the DART-MS analysis was also carried out at several temperatures. Due to the high sensitivity, simplicity, and no sample preparation requirement, the proposed analytical methodology could help conservators in the challenging analysis of unknown treatments in cultural heritage.

Advanced spectral imaging for noninvasive microanalysis of cultural heritage materials: review of application to documents in the U.S. Library of Congress.

Hyperspectral imaging was originally developed for remote sensing and astronomical applications, but adaptations of this technology have been of great benefit to the preservation of cultural heritage. Developments in noninvasive analytical techniques have advanced the preservation of cultural heritage materials by enabling the identification and analysis of a range of materials, utilizing their unique spectral response to nondestructively determine chemical composition, and determining states of deterioration and change due to environmental conditions. When used as a tool for noninvasive characterization of cultural heritage, these spectral imaging systems allow the collection of chemical identification information about materials without sampling, which is a critical factor for cultural heritage materials. The United States Library of Congress has been developing the application of hyperspectral imaging to the preservation and analysis of cultural heritage materials as a powerful noncontact technique. It allows noninvasive characterization of materials, by identifying and characterizing colorants, inks, and substrates with narrow-band illumination to protect the object while also monitoring deterioration or changes due to exhibit and other environmental conditions. Contiguous illumination from the ultraviolet, visible, and infrared spectral regions allows the capture of lost, obscured, and deteriorated information. The resulting image cube allows greater capabilities for mapping and coordinating a range of complementary chemical and spectral analyses. The capabilities of this technique are illustrated by a review of results from analysis of the Waldseemüller World Map, the L'Enfant plan for Washington, D.C., and the first draft of the U.S. Declaration of Independence.

Development of a technique based on multi-spectral imaging for monitoring the conservation of cultural heritage objects.

A new approach for monitoring the state of conservation of cultural heritage objects surfaces is being developed. The technique utilizes multi-spectral imaging, multivariate analysis and statistical process control theory for the automatic detection of a possible deterioration process, its localization and identification, and the wavelengths most sensitive to detecting this before the human eye can detect the damage or potential degradation changes occur. A series of virtual degradation analyses were performed on images of parchment in order to test the proposed algorithm in controlled conditions. The spectral image of a Dead Sea Scroll (DSS) parchment, IAA (Israel Antiquities Authority) inventory plate # 279, 4Q501 Apocryphal Lamentations B, taken during the 2008 Pilot of the DSS Digitization Project, was chosen for the simulation.