Chromatone

“Chromatone was the first commercially viable process of color print making entirely based on silver toning. It was developed in the early 1930s by the New Yorkers Francis H. Snyder and Henry W. Rimbach, who patented the toning methods and formulas.¹² Defender Photo Supply Company of Rochester acquired the production and sales rights of the process and marketed it under the name Chromatone in 1935. The company supplied all the materials in complete color kits, but individual items could also be bought separately as needed. Of all the processes then available to make color prints, Chromatone was considered the simplest; it took approximately two hours to make a print (Fig. 8.5). Three black-and-white separation negatives were contact-printed or enlarged on Chromatone print paper (a collodion stripping paper with a gelatin emulsion processed like a regular black-and-white photographic paper). After processing, the stripped film (the emulsion on a thin skin of collodion) was separated from the paper base, which was discarded. The next step consisted of toning each stripped film according to the color of the separation filter (cyan for the red filter, magenta for the green, and yellow for the blue). The three colored films were then squeegeed in turn, starting with the yellow impression, then the magenta, and finally the cyan, onto a gelatin-coated paper (Potter 1936). After assembly, the edges of the three films were trimmed flush and the print was allowed to set. Then the edges were affixed with gummed tape to a rigid board to prevent the print from curling up while drying (Fig. 8.6). Prints were assembled with the collodion side up for a very smooth, glossy finish.¹³ They could also be finished with a final coating of gum arabic or a lacquer (Dunn 1938). To obtain clearer highlights, which appeared slightly grayish due to the thickness of the collodion films, some photographers separated the gelatin emulsions from their collodion bases with acetone as the print was assembled. This operation had the added advantage of reducing the print’s tendency to curl on drying and provided a luster finish (Coote 1943). Chromatone was removed from the market in 1942 when Defender introduced Chroma-Relief, a line of dye imbibition materials (Nadeau 1997).”

(Pénichon, Sylvie (2013): Twentieth Century Colour Photographs. The Complete Guide to Processes, Identification & Preservation. London, Los Angeles: Thames & Hudson, on pp. 280–283.)