The Chemistry of Early Twentieth-Century Photography

Preparations for the exhibition Clarence H. White and His World: The Art and Craft of Photography, 1895—1925 recently inspired a collaboration between students at Princeton and Yale universities. In an effort to characterize the material history of a group of prints in the Art Museum's Clarence H. White Collection‚—specifically, to determine the printing processes used and to accurately date the prints, which were often made decades after the negatives‚—six undergraduates from Yale and three graduate students from Princeton came together in an unprecedented partnership spanning institutional and disciplinary boundaries.

Paul Messier, a photographic conservator at Yale's Institute for the Preservation of Cultural Heritage (IPCH), and Anne McCauley, the David Hunter McAlpin Professor of the History of Photography and Modern Art at Princeton, set out to enhance scholarly understanding of Clarence White's work prior to the exhibition curated by Professor McCauley. "I had already consulted with Paul about a paper I was writing on Man Ray, and we talked about the problem of identifying White's processes," reflected McCauley. The pair quickly recognized that in-depth technical analysis would be needed to answer questions about the great transitions that took place during the "pictorialist" period of late nineteenth- and early twentieth-century photography. Spurning glossy commercial printing papers that were often impermanent and that faded through time, pioneers like White selected commercial platinum paper (available after the late 1880s and normally matte), which gave very subtle halftones and was considered extremely resistant to fading. White and his fellow art photographers also sensitized a variety of drawing papers with hand-applied emulsions of gum bichromate, platinum, palladium, and cookbook mixtures of metallic salts. During World War I, platinum was requisitioned for the war effort, and commercial platinum paper became unavailable or very expensive, so manufacturers turned to palladium salts. Therefore, if one finds significant levels of palladium in the paper, the odds are that the print was made after 1917.

Partnering with Anikó Bezur, the Wallace S. Wilson Director of the Technical Studies Lab at IPCH, the pair selected undergraduates from across Yale, including students majoring in chemistry, cognitive sciences, biomedical engineering, art history, mechanical engineering, sociology, gender studies, and Russian literature. An X-ray fluorescence spectroscopy (XRF) "boot camp" was organized by Bezur, and the students were then ready to undertake real-world analysis of works from Princeton's collection. Bezur uses the elemental analysis technique to successfully characterize inorganic materials without the need for invasive sampling. "The XRF measures the number and energy of fluorescent X-rays, with a resulting spectrum of peaks at locations (or energies) corresponding to elements present, just like a fingerprint," she explains. "It enables us to identify photographic processes based on substrate, image forming material, and toner and make new data accessible to scholars for the first time." With portable instruments brought to campus, the Yale students, together with Art and Archaeology graduate students at Princeton, examined Clarence White photographs, completing an analysis of eighty images over two days to establish approximate timelines for each print based on the metals used to form the images.

The Yale team then analyzed the results from the workshop, and their findings led to many of the objects receiving a reassignment of previously recorded printing techniques and dates. Having uncovered the processes that White used, the next step was to make the new data accessible to scholars. "The results from this work allowed us in the exhibition catalogue to confirm the process identifications of the prints from the analysis," explained McCauley. "And thanks to Katherine Bussard, curator of photography at the Art Museum, the partnership enabled our history of photography graduate students to see how XRF works and what it can tell us."

"Working with our colleagues from Yale and seeing the data generate live on screen, I came to realize the range of expressive effects Clarence White was able to produce from the array of common photographic processes," said Daniel Peacock, one of the participating Princeton graduate students. "I left the workshop appreciating the pictorialist toolkit as more complicated and experimental than I 
had expected." "All the students did an amazing job," commented Messier. "Other collections from the period probably have similar, or even greater, rates of misclassification. This data point alone will inspire other curators and conservators to improve the accuracy of their catalog assignments of art photography from this moment in its history." This collaboration is just one more example of how the Museum, as Director James Steward notes, remains "profoundly committed to providing as many hands-on experiences for our students as possible."

For more on the collaboration, view the related video online at artmuseum.princeton.edu/learn/explore/museum-videos.

Princeton University Art Museum Winter 2018 Magazine