Visualizing underdrawings in medieval manuscript illuminations with macro‐X‐ray fluorescence scanning

Abstract

The element‐specific distribution maps generated by scanning macro‐X‐ray fluorescence (XRF) spectroscopy are providing cultural heritage researchers with information about the composition of materials present in works of art and, more importantly, unprecedented insight into the techniques employed by artists in their creation. One of the advantages of macro‐XRF scanning is that the X‐rays probe materials in subsurface layers, allowing, for example, visualizations of hidden paintings to be produced. Consequently, macro‐XRF scanning has found wide use in the study of paintings, but the high spatial resolution also makes it particularly well suited for the study of the small‐scale painted illustrations and decorative elements found in illuminated manuscripts. The preliminary drawings made by manuscript illuminators to plan a painted composition—known as underdrawings—provide evidence relating to artists' creative vision and working process but are difficult to examine because they are generally hidden under the surface paint layer. Traditionally, underdrawings in a carbon‐based medium are visualized using infrared (IR) imaging. In this study, results of the analysis of painted illuminations from medieval illuminated manuscripts demonstrate that macro‐XRF scanning can visualize underdrawings in other materials, such as iron‐gall ink, metalpoint, and pigmented inks/paints, thus serving as a useful complement to traditional IR imaging. For manuscript illuminations in bound books, this study also discusses the use of interleaving materials to reduce unwanted signals from underlying folios. The ability to reveal manuscript underdrawings will help elucidate artistic intent and workshop practice and provide a new way to examine the history of medieval drawing.