An early 16th century choirbook from Italy, depicting an illustration of St. Peter and assembled saints.

Portable x-ray fluorescence has found another application in cultural heritage research at Cornell. Over the course of three days in late February, the Landscape and Objects Laboratory’s portable XRF system was used to examine twenty-seven European illuminated manuscript fragments in the Cornell Library Rare and Manuscript Collections. Dr. Louisa Smieska, a postdoctoral researcher at the Cornell High Energy Synchrotron Source (CHESS), collaborated with Ruth Mullett, Medieval Studies graduate student, and Dr. Laurent Ferri, Curator of Pre-1800 Collections, to complete the study.

Detail of 15th century manuscript copper and barium distribution.

This survey was aimed at identifying the pigments used in the lavishly decorated pages in Cornell’s collection. The team was particularly interested in the blue pigments, and in metallic areas that could be gold. Twenty-three of the manuscripts examined contained copper-based blue pigments, which are probably dominated by the copper-rich mineral azurite. Some of these manuscripts will be examined further at CHESS later this spring to try to determine whether the other trace minerals in azurite blue regions reveal information about the pigment’s provenance. Three manuscripts yielded XRF spectra that could indicate the presence of the precious and costly blue mineral lapis lazuli; these fragments will need to be examined further to confirm this finding. One manuscript contained smalt, a ground cobalt glass, which is an unusual (but not unheard-of) pigment for illuminations.

In contrast with the scarcity of costly blue pigments in these manuscript fragments, eighteen of the twenty-one fragments with metallic regions contained gold. Although today gold is considered particularly valuable, the relative cost and rarity of lapis lazuli when these fragments were prepared may have been greater than gold. The survey also identified metallic regions containing tin, which could indicate mosaic gold, a synthetic tin sulfide pigment. The research team is excited to compare this pXRF data with other spectroscopic analyses in the coming months.

The Landscape and Objects Laboratory’s portable x-ray fluorescence (pXRF) system has once again visited the Herbert F. Johnson Museum of Art. Dr. Louisa Smieska, a postdoctoral researcher at the Cornell High Energy Synchrotron Source (CHESS) whose studies focus on materials analysis of cultural heritage objects, was recently trained in pXRF data collection at the LoL. On January 15, 2016, Dr. Smieska collaborated with Dr. Andrew Weislogel, the Askin curator of Earlier European and American Art at the Johnson Museum, to collect XRF data from selected regions in several 17^th-century Dutch paintings and one 20^th-century.

The goal of the study was to survey the pigments used to create these very different paintings, with a particular interest in the blue pigments. Several possible blue choices were available to 17^th-century painters, including plant-derived indigo, copper-rich azurite, ground cobalt-rich glass (smalt), and the precious aluminosilicate mineral lapis lazuli (natural ultramarine). Knowing which one was used is important for understanding the original expense of the painting, since ultramarine was much more costly than the other options. Identifying pigments can also hint at how the original composition might have looked, since the color of indigo and smalt can fade over time.

Dr. Louisa Smieska (CHESS) and Dr. Andrew Weislogel (Johnson Museum) use the pXRF to examine van Schrieck’s Still Life with Thistle (ca. 1670).

Pictured are Dr. Smieska and Dr. Weislogel collecting pXRF data from a c. 1670 painting by the Dutch artist Otto Marseus van Schrieck. The blue thistle blossoms in this picture are painted with a copper-containing pigment, possibly azurite. The pXRF analysis of other locations in this painting indicated that the green pigment used in the thistle leaves is also copper-based, while the bright red details in a few of the butterfly wings are painted with a mercury-containing pigment, most likely vermilion. The results from this afternoon of analysis will be used to identify paintings that could be good candidates for scanning x-ray fluorescence imaging at CHESS in the next few months.