Volume 2, Number 2, May 1980, p.6

Meeting Review: Preservation and Restoration of Photographic Images

by John Twilley

"Preservation and Restoration of Photographic Images," Rochester Institute of Technology, Rochester, New York, March 3-6 (an ongoing program).

Conservation scientist John Twilley recently attended the Seminar on Preservation and Restoration of Photographic Images at RIT as an advisor to the California Museum of Photography at the University of California, Riverside. He has related the following impressions of the Seminar.

The slate of speakers included representatives from quite diverse backgrounds--industrial, academic and private researchers and those involved in conserving or copying photographic collections. The attendees represented even more diverse institutions, the only common denominator of which would seem to be their extensive photographic holdings. Collections belonging to civil, academic, historical, military, religious and private groups were represented as well as professional photographers. Holdings in these collections ranged from those which are of value only for their informational content (microfilm records) to those which are primarily media of artistic expression. In between there are a great many items which represent unique historical records not only in their image content but in their own material and technical nature. The quantity of material held in these collections is immense, with a surprising number of 500,000+ collections being represented at this one meeting.

Being able to gather up, all in one place, so much information about the storage and stability of images from all periods was the greatest advantage in attending this seminar. The great majority of the information presented by the speakers has been published, and is widely distributed through professional journals, corporate literature, and hobbyist publications. A few speakers, notably Henry Wilhelm, presented some very recent findings. Susan Barger of the University of Pennsylvania described the research plans which she and Irving Pobboravsky are following in studying daguerreotypes. James Reilly and Irving Pobboravsky showed examples of contemporary albumen prints and daguerreotypes (respectively) which have been produced in the course of their research into early processes. Reilly has authored a well-illustrated test on albumen prints which will be available through Light Impressions Corp. shortly.

Two very important points brought out by Henry Wilhelm related to light fading of color prints (Kodak) and structural stability of Polaroid films. His experiments have shown that accelerated aging tests as they are commonly conducted by Kodak involving only elevated light levels, substantially underestimate the rate of fading under common light levels. He did not speculate upon the reason for this. It seems however, that since dye fading is known to be accelerated by elevated moisture levels and to involve oxidation, that the availability of moisture and oxygen in the dye layers may be a new limiting factor when the light level is raised above a certain point. Perhaps better correlation between accelerated aging and long term fading would be achieved with an increase in the partial pressures of water vapor and oxygen as well as light intensity during these tests. Wilhelm has recently seen a number of cases of cracking of the receiving layer (dye) in Polaroid instant color films resembling craqueluer in a painting. These haven't been related to any direct cause as yet, but it appears that they may be related to stress experienced years previously even in the handling during development.

Wilhelm, along with Klaus Hendriks of The Public Archives of Canada, are authoring an extensive text on color film and print stability which they are publishing themselves. It may not be available for quite some time, but promises to be an exceptional piece of work.

Of interest to almost all conservators is the permanence of documentation photographs and x-rays. The proper processing and storage of these is as important as the act of documentation itself. Processing shortcuts or laxness (such as inadequate washing or excess fixing time respectively, especially critical when using resin coated papers) and certain commercially available processing chemicals (such as one particular clearing agent which causes retention of ten times as much hypo as a well washed control!) should be avoided.

The two most prominent shortcomings of the Seminar--at least from the conservator's perspective--were the lack of clearly defined approaches to preservation of the very different collections and the lack of a clear presentation. Specifically. what does and does not constitute modern "conservation." The term "preservation" was often used to refer to a process leading to the reproduction of an image in a more stable (sometimes entirely different) format and simultaneously to refer to the actual stabilization of the original. The distinction was usually clear in the case of a unique "direct positive" image such as daguerreotypes. However, the distinction became very muddled in the context of negative/positive process images. Three factors relative to printing papers make modern prints from old negatives essentially different from original prints. Density range, image tone and surface texture will cause differences in even the best preserved images when reprinted. In the usual case where contrast and highlight detail have been lost on aging and where intentional toning, dodging and other darkroom manipulations have been carried out on the original prints--a new print can never reproduce the original image. Therefore, even though the only "original" is the negative itself, contemporaneous prints are often times unique, irreproducible originals in their own right. For many collections this distinction is academic. More discussion of the philosophical problems posed by these constraints is essential for some types of collections to develop a responsible conservation policy.

Anyone planning to attend one of these bi-annual seminars would make the best use of the opportunity by familiarizing themselves with the simple photographic processes in advance and thereby availing themselves more fully of the opportunity to pursue less readily available information. Several of the individuals working in this area will be speaking at the up-coming AIC meeting in San Francisco, May 22-25.

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