In February of 2012, the Indianapolis Museum of Art mounted a works on paper exhibition created by IMA Prints, Drawings & Photographs Curator Marty Krause entitled “Looking West.” This exhibition featured collection prints, drawings, photographs and watercolors by artists of the 19th & 20th centuries who were captivated by the scenery and culture of the American West. Two of the photographs chosen for this exhibition were taken out of storage for the first time since their acquisition in 1988. They were listed in the museum’s database as works by Edward Sheriff Curtis and identified as “orotones.”
It is one of my responsibilities to inspect every artwork prior to display in our galleries to make sure that there are no compelling condition problems that would require treatment before the installation. The orotones were stored with the oil paintings, hanging high on massive wire mesh storage racks suspended from the ceiling. I had to climb a ladder to reach them, and at the top I leaned forward to remove the archival foamboard light shields that were fitted around their frames to protect them from unnecessary light exposure. What I uncovered were two gleaming images, casting a quiet golden glow that seemed slightly miraculous given the cold illumination provided by the overhead fluorescent lights. The orotones shone as if lit by internal church candles, and I was immediately intrigued by the beauty and presence achieved by this esoteric photographic process.
Edward Sheriff Curtis was both prominent and prolific in the history of orotone images. His most famous endeavor involved amassing a documentary record of Native American cultures through staged scenes and portraiture, and the use of this particular technique enhanced the romantic appeal of this body of work. The IMA photographs are entitled Three Chiefs, Piegan and The Vanishing Race. They were in identical frames of gilded wood with decorative corner elements, and I came to learn that these were a common type of frame associated with Curtis’s work, personally selected to properly enhance and dignify his images.
What are orotones? This turned out to be a much more complicated question than anticipated. Other names for them include Goldtones and Curt-tones, the latter term coined by Curtis himself. The Latin word for gold is aurum, approximated by the prefix ‘oro’ which seems an obvious reference to the golden appearance of the images. This has lead to the misunderstanding that all orotones utilize actual metallic gold within the process. In truth, Curtis’s orotones were created by projecting a photographic negative onto a glass plate that had been pre-coated with a silver-gelatin emulsion, thereby creating a ‘positive’ image. The image was developed and fixed, and the emulsion was then coated with a layer of ‘bronzing powders mixed with banana oil’ to produce a backing color that enabled the highlights and shadows to be discernible, thus rendering the image readable. The ‘bronzing powders’ (metallic powders in a liquid carrier) were probably variable mixtures, but in Curtis’s work, they have been found to contain copper and zinc (note: bronze is technically defined as an alloy of copper and tin; copper and zinc are the components of brass). This metal combination was confirmed at the IMA through a brief scan using a handheld X-ray fluorescence spectrometer. The ‘banana oil’ is amyl acetate in acetone and benzene, with the addition of a small amount of proxylin, which is a cellulose nitrate lacquer. The amyl acetate solvent is produced synthetically, but it has the distinct smell and taste of bananas, which explains the persistent use of the term ‘banana oil.’ It takes a great deal of skill to lay this coating over the emulsion flawlessly, which may help to explain the relative rarity of this process and Curtis’ justifiable pride in his mastery of the technique. He is even thought to have modified the materials to gain the precise aesthetic that he wanted, although this speculation has not been well documented.
Now that we understood what orotones were, we knew that we needed to re-examine our stewardship practices surrounding them to make sure that we were giving them the care they needed in order to survive into the distant future. It is very fortunate that we have the advice of visiting photograph conservator Paul Messier (which I wrote about here), contracted by the IMA for a condition survey of all collection photographs through a generous grant from the Institute of Museum and Library Services (IMLS). The following information is excerpted from Paul’s survey of The Three Chiefs, Piegan: