The Getty Conservation Institute (GCI) and Paul Messier, Inc. recently produced a full-day symposium on "Understanding 20th-Century Photographs: The Baryta Layer Research". This symposium discussed many of the newest methods to date and provenance photographs.
Giacomo Chiari, chief scientist at GCI, opened up the symposium by giving an overview of the types of ongoing research and their potential benefits. He noted that it should be possible to determine how much light and what type would be damaging to a given paper, to map fungi and other types of mold that are not visible to normal light, to date and provenance prints more accurately, and to determine exactly what process was used to make a print (an Atlas of this latter work is well underway at the Getty and will be available in the future).
Paul Messier then reviewed the current state of research in relationship to optical brighteners added to photographic papers.
Utilizing Messier's extensive library of dated photographic paper--the largest in North America, results indicate that, to date, no papers made prior to 1950 have tested positive for optical brighteners, and that only about 1/3 of the papers from the latter part of the 1950s tested for brighteners. The survey found peak use of the brighteners in the periods 1960-1964 and post-1980. Brighteners can be detected using an Ultraviolet Lamp, commonly know as a black light (use of UV protected eyewear is recommended when using a black light). In the post-1980 period 78% of fiber-based papers tested showed brightening agents. The survey also concluded that brighteners were mostly found in the emulsion side of papers produced prior to 1960. After 1960, brighteners were predominantly found on both the emulsion side and paper base.
Messier also briefly discussed ongoing work on analyzing the actual paper fiber by type and even by tree species and percentage of mixed fibers to further help date papers. As one example that can be tested, the existence of bleached Kraft paper in photography papers is a relatively recent phenomenon, coming into prominent use in the 1960s and 1970s. This is something that conservators can easily test for. Messier is currently working with the New York Museum of Modern Art on expanding the fiber analysis database.
Messier also discussed the use of dating photographs utilizing photography paper companies' logos and names. I am working on a joint project with Messier and his group to present this material.
Dusan Stulik, senior scientist at GCI, and a team of scientists and conservationists from the Getty, California State University and the Nuclear Reactor Research facility at the University of California Irvine studied trace elements in the baryta layer of photographic emulsions using about 580 paper samples from the Messier photography paper library, and then discussed the results of their research at this meeting. The scientists utilized several technologies, including X-Ray fluorescence spectrometer (XRF), plasma-mass spectrometry (ICP-MS) and neutron activation analysis (NAA).
In addition, Renaud Duverne, Centre de Recherches sur la Conservation des Documents Graphiques (Paris) discussed his additional research on structural measurements (thickness of the layer, etc.) and particle size analysis of the baryta coating.
All these new techniques lead the scientists to feel that there are profitable lines of inquiry that could lead to additional methods to both date photographic papers and even to provenance images, given that most photographers tended to stick with one or two photography papers for the bulk of their work. Their testing database will need to be expanded, as well as the library of photographic papers, but already testing exists through these methods that would allow conservators to match chemical and physical markers of many baryta-coated black and white photographic papers to determine age and specific type of paper, and perhaps confirmation of provenance of a specific photographer.
According to Stulik, standards for XRF use calibration will be made available to all potential users of the new provenancing methodology to facilitate an easy comparison of data, regardless of type of XRF used, or of experimental parameters. Conservators should contact GCI and Stulik about this. GCI is also making available a traveling laboratory to train conservators at other sites in the world.
Anne Cartier-Bresson, director of the Atelier for the Restoration and Conservation of Photographs of the City of Paris (ARCP), was the guest lecturer. This part of the program was open to the general public and it was a very nearly full Getty Lecture Hall for the presentation. Cartier-Bresson, not only detailed her work in Paris, but reiterated other speakers calls for a more unified approach to identifying and solving conservation issues.
The upshot is that while the technology is not there to test all papers, the database of information continues to growth and expand to several areas of study. Institutions are beginning to work more closely together, at least to develop standards. This will mean more reliability and specificity in testing and determining the age of photographic papers, matching papers to specific photographers, and determining other important characteristics of 20th-century photography prints, including the specific process of the print (especially of "alternative" processes), the paper's ability to handle light (what type and how much), optical brightener fastness, and "invisible" mold and fungi growth.
If you have or know of properly dated and provenanced photographic paper supplies, particularly prior to 1950, and would like to donate or help this project, please contact Paul Messier at firstname.lastname@example.org and Dusan Stulik at email@example.com .