Reading 4

Reilly, J. M. (1986). "Chapter IV: Identification of 19th-Century Photographic and Photomechanical Print Processes." Care and Identification of 19th-Century Photographic Prints. Eastman Kodak Company. (p. 48-72)
ISBN: 0-87985-365-4

Since I'm doing my internship in the photographs department of an archive, I should obviously come out of this experience with some familiarity with nineteenth century photographic processes. I've already looked at some nineteenth century photographic prints with Brad and we will go through more examples before my internship is over, but I thought it would be a good idea to read a little on this topic, as well.

This chapter provides good, systematic guidance on identifying nineteenth century photographic and photomechanical processes. It includes a description of the equipment an archivist needs to perform these identifications, descriptions of the most common processes, a flowchart for identifying these processes, and detailed instructions on how to work through the flowchart. This chapter obviously can't replace hands-on experience with nineteenth century prints, but it is certainly a useful supplement and reference.

A lot can be learned about a print by examining it with the naked eye and with a simple 10X magnifier, which I think would be similar to the loupes we use in the Indiana University Archives photographs department. However, the author also indicates that a 30X stereomicroscope is needed to distinguish between some processes.

While the book is devoted to images on paper supports, the chapter briefly addresses daguerreotypes, ambrotypes, and tintypes. Daguerreotypes were most popular from the 1840s to the 1860s, and Reilly writes that they "consist of a positive image on a thin copper plate with a highly polished, mirror-like coating of silver... In America, daguerreotypes were most often placed in small hinged cases made of wood with a leather or paper covering, or in the so-called 'union cases' made of a molded thermoplastic material" (50). Some of the daguerreotypes from the University Archives collection are in union cases. Reilly indicates that a daguerreotype can be easily identified by "its highly polished silver support and its quality of appearing either as a negative or a positive depending on the angle of view and the direction from which light falls on it" (80).

Reilly writes that ambrotypes and tintypes are similar in that they "[b]oth consist of a positive, physically-developed silver image in a collodion binder on an opaque, non-reflective support... The two processes essentially differ in their supports: ambrotypes have a glass support, while tintypes have a support made of a thin sheet of lacquered iron" (51). He indicates that cased ambrotypes can be distinguished from daguerreotypes by the fact that the image remains positive regardless of the angle at which it is held, and a tintype which has been placed in a case can be identified by holding a magnet against the glass, since this will reveal whether or not there is an iron support.

The bulk of the chapter is devoted to identifying the remaining photographic and photomechanical processes. The first step in this identification is to determine whether the print has a patterned image grain or a continuous tone, since this will be a good indicator of whether it is a true photographic print (continuous tone) or a photomechanical print (patterned image grain). The next step is to look at the layer structure. Nineteenth century photographic prints may have from one to three layers. Some prints consist only of a paper support layer, some have both a paper support and a binder, and some have a baryta layer between the binder and the paper support. A binder is "the transparent layer in a photographic material in which the final image material is suspended and protected" (27) and a baryta layer is "a coating of white-pigmented gelatin which covers the paper support... forming a smooth, reflective substrate for the binder layer" (60). The third and final decision-making step is based on "individual characteristics of the processes," such as "color, typical forms of deterioration, characteristic grain patterns, etc." (53).

After laying out this decision-making process, Reilly provides a flowchart and spends the remainder of the chapter describing in detail how to identify the major photographic and photomechanical processes of the nineteenth century by following this flowchart. The processes he examines are letterpress halftone, photogravure, collotype, salted paper print, cyanotype, platinotype, albumen print, carbon print, woodburytype, gelatin printing-out paper, collodion printing-out paper, matte collodion printing-out paper with gold and platinum toning, and gelatin developing-out paper. Letterpress halftone, photogravure, collotype, and woodburytype are photomechanical processes while the rest are true photographic processes.

Overall, this chapter seems to provide a good overview of the major types of nineteenth century photographic prints and straightforward guidance on how to identify the processes that created them.