42nd Annual Meeting – Photographic Materials Session, May 31, “Comparative Study of Platinum Prints in the Museum of Fine Arts, Houston Collection and the Early 20th Century Kodak Platinum Print Samples” by Saori Kawasumi Lewis.

Ms. Kawasumi Lewis presented research conducted at the Museum of Fine Arts, Houston during her third year internship. This project was joint with the National Gallery of Art’s Platinum/Palladium initiative. She was happy to close the conference with this talk, as it could serve as a teaser for the upcoming Platinum/Palladium Symposium.
Ms. Kawasumi Lewis had the unique opportunity to compare platinum prints in the MFAH collection to a platinum print sample set produced by Kodak c.1902-1910, owned by a private collector. The Kodak sample set is a great resource for this study because it was commercially produced and each product has been identified on the object. She hoped that characterizing these known samples would help identify unknowns, particularly artwork in the museum’s collection. To test this, she compared the Kodak sample set to a small group of  prints in the MFAH collection. She used a variety of analytical techniques to narrow down the possibilities, finally resulting in a close match with one print in the collection: Lucille Tomajon, by Gertrude Käsebier.
Ms. Kawasumi Lewis presented this research in a systematic approach, showing us how each analytical method helped narrow down the field of possible matches. Each step ruled out some of the sample set and the MFAH group.
To begin, she led us through a bit of the chemistry of platinum printing, which is a semi-printing out process. Significant to the research, she detailed that an artist could add mercury in either of two distinct steps – sensitizer or developer. For greater effect, mercury could be added in both steps. Starting in the 1880s, mercury was added to commercially available papers. Palladium paper and platinum/palladium mixtures were also available.
Ms. Kawasumi Lewis described the analytical steps that helped her find affinities between the sample set and photographs in the collection. Comparison included: date, thickness, sheen, texture, color, and elemental composition. Ten platinum prints by Clarence White, Gertrude Käsebier, Fredrick Evans and others were chosen from the MFAH’s collection of pictorialist photographs as a comparison group.
First, X-ray fluorescence spectroscopy (XRF) was used to determine the elemental composition of the prints. Readings were collected from Dmax and Dmin areas using a Bruker handheld Tracer, and an Artex XRF unit. XRF data was analyzed using the counts from the instrument, which were normalized according to the Rh Kα line. In addition to platinum, mercury, palladium and lead were found in the prints. Some trends were identified: Mercury was abundant, though variable, so this required more investigation; palladium was present in several of the Kodak samples, but only one of the MFAH prints. This narrowed down the field a bit, ruling out the Kodak samples with palladium.
In order to determine if mercury variability was due to differences in the time of addition (sensitizer or developer), Ms. Kawasumi Lewis created mockups using a variety of methods described in the literature. She found that her mercury sensitized sample was most similar to the Kodak sample prints and most of the MFAH platinum prints. Not surprisingly mercury levels were highest in prints that had been sensitized and developed with mercury. This narrowed down the group a bit more by ruling out MFAH prints with high levels of mercury.
Next, surface texture was analyzed using Paul Messier’s texture scope and experimental design. This step helped to narrow down the list further by comparing the descriptions of surface (i.e. smooth, rough), to the MFAH prints. This further reduced the possibilities, so the field of possible matches was limited to only a few prints.
As the final step, Ms. Lewis used color to narrow down her final group of prints using a spectrophotometer to quantify red and yellow saturation. (As a note of caution, she mentioned that the color of platinum can be effected by more than just choice of paper. Temperature during processing, ageing and other factors can change the color of prints.) This narrowed her group down to just the Käsebier and the sample for Kodak Etching Sepia Smooth paper. This is strong evidence that Käsebier used this paper to create the print because the prints are alike in elemental composition, texture and color.
More research could help definitively characterize the paper Käsebier used for this print, but Ms. Kawasumi Lewis’ work gives us a good indication of the materials used by the artist.