Use of Imaging Spectroscopy and in situ Analytical Methods for the Characterization of the Materials and Techniques of 15th Century Illuminated Manuscripts

Abstract

This study combines site-specific in situ analytical techniques with non-site-specific reflectance imaging spectroscopy and multispectral infrared reflectography to characterize pigments and underdrawing materials in fragile, light-sensitive illuminated manuscripts. In situ methods implemented in this study included fiber optic reflectance spectroscopy and x-ray fluorescence, as well as multispectral visible and near-infrared reflectance imaging spectroscopy and multispectral infrared reflectography. Imaging spectroscopy was used to map areas having similar diffuse reflectance spectra, and the site-specific methods were used to further identify the primary pigments present. This combined approach was used to examine an illumination by Lorenzo Monaco (ca. 1370–1422 or after) and his workshop on the Praying Prophet, in the collection of the National Gallery of Art in Washington, DC (NGA), from an early-15th-century gradual on parchment (codex H74) currently at the Museo Nazionale del Bargello in Florence. The combination of the results along with microscopic examination led to a more complete understanding of the working methods used to create the Praying Prophet, including the primary pigments present and the two forms of underdrawing, ink and metalpoint. These results also allowed for a comparative examination of the primary pigments used in 13 other folios in codex H74. Multispectral infrared reflectography imaging and fiber optics reflectance spectroscopy confirmed that the primary pigments and preparatory drawing used in the NGA folio were consistent with those used in the other folios.