Conservationists at the Getty Conservation Institute have developed a combination of techniques that could revolutionize the authentication and identification of historic photographs and their type of process.
In the past, photographs have usually been identified through visual or microscopic inspection, a method that relies on connoisseurship and is not error-proof. Now, the Getty researchers have revealed that most 20th-century printing processes leave behind distinct chemical traces that are nearly as unique as fingerprints.
The Getty's Dusan Stulik and Art Kaplan, along with photo conservator Tram Vo, used nondestructive X-ray fluorescence spectrometry and Fourier-transform infrared spectrometry analysis to analyze the chemical signatures of numerous historic photographic processes, of which there have been more than 150 since the beginning of photography. The trio found that by precisely measuring amounts of barium and strontium in a given print--both elements are both found in a mineral coating that became part of black-and-white photographic paper by the end of the 19th century and would remain part of nearly all paper manufactured until the 1970s--they could determine its origin.
"We've found that photographic papers produced by different manufacturers at different times contain distinct concentrations of barium and strontium. These distinctions in the composition of photographic papers and photographs can be used to determine who made the paper, and when," explained Stulik.
"This finding is significant for museum curators, collectors, and conservators of photographs because a precise [analysis] could demonstrate that a photograph in question has been mistakenly identified as being much older than it actually is, or that a certain photographic paper was not actually available during the life of a particular photographer."
Some of the resulting data have also been incorporated in a new database of chemical profiles allowing for instant identification of hundreds of different processes and even toning techniques using the two types of analysis. On a recent visit to the Getty, I watched as several photographs were placed under the infrared analysis machine and the specific print process was instantly identified by the software.
Stulik explained to me how the group was building up specific information databases on the prints of several major photographers, which may lead to authentication methods for those photographers.
Last year Stulik and Kaplan were invited to Paris to work with the Henri Cartier-Bresson Foundation and the Atelier de Restauration et de Conservation des Photographies de Ville de Paris in analyzing Henri Cartier-Bresson’s original photographs. This initial work would aid in building a database of information on the photographer’s existing prints, against which other prints attributed to him could be compared in the future.
“Importantly, this new approach is not just a theoretical approach, it’s also practical. It expands our knowledge of Henri Cartier-Bresson’s prints tremendously--his processes, the photographic paper he used, and where and when he printed photographs. We will be much more able to characterize his prints in future," said Dr. Anne Cartier-Bresson, director of the Atelier de Restauration et de Conservation des Photographies de Ville de Paris, and Henri Cartier-Bresson’s niece. “To my knowledge, this is the first time this type of methodology has ever been applied to this kind of problem. To study one photographer in all of these aspects is unprecedented.”
It is hoped that the process would be able to distinguish genuine from counterfeit prints in a scientific fashion.
The Getty is planning to make some of their findings available to other public institutions.
To download a pdf file of the original published paper on the methodology just click here: http://www.ndt.net/article/art2008/papers/050Stulik.pdf .