DIFFERENCES IN IMAGE TONALITY PRODUCED BY DIFFERENT TONING PROTOCOLS FOR MATTE COLLODION PHOTOGRAPHS
For many years, caretakers of photograph collections and photograph conservators have mistakenly identified matte collodion prints as platinum prints. James Reilly (1986) finally acknowledged the wide use of this process over approximately three decades, from 1890 to 1920, in his book Care and Identification of 19th-Century Photographic Prints. It has since been assumed that matte collodion prints were all neutral black in tone. A brief examination of study collections at The Better Image, Pittstown, New Jersey, and the Image Permanence Institute, Rochester, New York, showed that this was not always the case. Although matte collodion prints usually display a typical neutral black tone, some may show cooler or warmer tones. The purpose of this study is to examine the possible factors responsible for these differences in tone. A brief history of printing processes will be given, followed by a description of the matte collodion process and the different toning protocols described in photographic treatises and journals of the period. Results of elemental analysis will also be discussed.