11 CONCLUSIONS

The arrival of commercial, ready-to-use photographic papers was a benchmark in the history of photography. It completed the movement that had been initiated with the introduction of the dry-plate negative, and photographers progressively lost control of the production of photosensitive materials. Matte collodion photographs were popular from approximately 1894 to 1920 and were introduced to supply an aesthetic need for matte surfaces and neutral tones. Although the literature offers a wide variety of toning recipes, it is often mentioned that gold, platinum, or a combination of both toners were the most commonly used for matte collodion prints. The limited number of photographs analyzed in this study does not authorize a conclusion about the predominant use of gold or combined gold and platinum toners; however, the results do agree with this statement.

This study also revealed that photographers praised collodio-chloride papers mainly because any color, from red-brown to a deep rich purple-black, or even a cold black, could be obtained with them. The factors responsible for these color differences such as the conditions of exposure, the negative quality, the emulsion formula and paper brand, the metal used for the toning bath, the toner concentration, the time in the bath, and the temperature of the bath, were identified through the literature of the period and the study of the mechanism of toning. Analysis confirmed that a toning bath could produce prints of varied tones. Gold toning, for example, can provide almost neutral tones if the substitution of photolytic silver for gold-silver alloy is thorough. A trained eye might be able to distinguish correctly different toning protocols (gold versus gold/platinum for example), but positive identification of the toner is almost impossible without elemental analysis.

ACKNOWLEDGEMENTS

The author would like to thank Mark T. Wypyski and the Metropolitan Museum of Art for the analysis; Nora Kennedy, Doug Nishimura, and Doug Munson for their input during the project; and Peter Mustardo, Debbie Norris, and James Reilly for the samples of matte collodion photographs. Thanks also go to Peggy Ellis, Doug Severson, and Carol Turchan for their revisions and suggestions.