Seeing in the dark: Challenges in the interpretation of x‐ray fluorescence element distribution maps associated with black paints

Abstract

AbstractDuring the conservation of easel paintings, black draperies or dark backgrounds often prove problematic to treat and understand in terms of condition. Despite most black pigments in Old Master paintings not intrinsically containing high atomic number elements, the investigation of black paints is one of the National Gallery's major uses and most helpful applications of x‐ray fluorescence (XRF) scanning. As a visual tool, XRF element distribution maps of black paints are useful for assessing the extent of overpainting or condition of any surviving original paint beneath, and for revealing the original modelling. However, interpreting the XRF element maps can be challenging. It is important to consider not only the primary compositions of black or dark pigments, but to have an understanding of other possible associated materials and more broadly of historical painting techniques, artists' practices and the paint stratigraphy. Through a series of case studies, this paper demonstrates how a detailed knowledge of historic painting materials and techniques, based on study of documentary sources and archives of materials‐based evidence from the analysis of paint cross‐sections—both from the paintings being studied and related works—aids and enriches interpretation of XRF element maps of black paints. While samples are invaluable in understanding exactly how—and with what materials—such regions were painted, they are not always representative and scanning XRF may be of complementary benefit in providing a more holistic view of pigment distribution. The examples presented range from the fifteenth to the seventeenth century from both Northern Europe and Italy.