Chart: Pigments used by Winslow Homer
Conservation scientists at the Art Institute of Chicago employed a suite of state-of-the-art tools to shed new light on Winslow Homer’s pigment usage and fully understand the development of his palette. We began with X-ray fluorescence (XRF) spectrometry, a noninvasive method that uses a focused beam of X-rays to excite the atoms that constitute a pigment and analyze the fluorescence that occurs. The technique registered the characteristic fingerprint of each element present in a particular area, allowing us to identify the inorganic pigments. Next we performed selective sampling with a microscopic tungsten needle in order to identify the organic colorants with certainty and confirm the components of very thin washes. Here we used the complementary techniques of micro-Raman and micro-FTIR spectroscopy. These processes interrogate microscopic grains of pigment and record how different molecules interact with laser and infrared light, respectively. The sequential experimental procedure just described was particularly relevant in the case of fugitive organic blues, pinks, purples, and reds, which were key to creating the atmospheric qualities of many of Homer’s watercolors. Detailed results of the pigment analysis are reported in this chart.
-Francesca Casadio, Andrew W. Mellon Conservation Scientist, Art Institute of Chicago