Fingerprinting photographs

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Old photographic papers.

In 1999, Paul Messier was working as an art conservator in Brighton when a pair of clients approached him with a question: They’d recently purchased a set of prints purportedly made by the famed early 20th-century photographer Lewis Hine and wanted to know if they were authentic. Messier set out to provide an answer but soon discovered that the field of photography had very little to go on when it came to establishing the provenance of a print.

"I kind of couldn't believe that these objects were so puzzling," he says. "Why was it such a difficult problem to sort out whether a photograph was made pre- or post-1940?"

Since then, Messier has worked to change that, and, over the last 17 years, he's been the leading force behind a quiet revolution in the way art conservators analyze photographs. Where previously they'd relied largely on the content of the image and the look and feel of the paper to determine who took it and when, Messier has helped develop a suite of forensic tools that allow conservators to establish facts about a photograph with the exactitude of a crime scene investigation.

"You can come up with a fingerprint for [the materials a photographer] is using at a certain time period," says Adrienne Lundgren, a photography conservator at the Library of Congress who has collaborated with Messier. "It becomes a virtual signature. It's not signed, but it's all but signed."

Messier's inquiry into photographic materials began with a lot of time on eBay. Soon after being presented with the Hine images, he started buying all the old, unused photographic paper he could find — the blank material on which photographers print their negatives. As he acquired samples, he analyzed the fibers used to make the different papers. He found that what a photographic paper is made of tells you a lot about when it was made: At the beginning of the 20th century, rag fibers of cotton or linen were common; as the century wore on, wood pulp was used increasingly, and from different species of trees during different time periods. "If you encounter a photographic paper with eucalyptus, there's a pretty good chance it's a Kodak paper made in North America in the 1960s," Messier says.

In addition to fiber composition, Messier has developed other measurements to locate a photographic paper in history. He measures paper thickness using a micrometer, gloss using a gloss meter, and color (or fluorescence) using a spectrophotometer. With those four dimensions, he can say quite a lot about where, when, and by whom a negative was likely printed.

"If it's Man-Ray or Ansel Adams, I can tell you this has a warmer tone or it's glossier than a typical Ansel Adams made in this decade, so maybe it's an anomaly, or I can say it's consistent with the papers Ansel Adams was using for a particular period of time," Messier says.

Messier's goal has been to create a large-scale database of photographers and their print attributes that could be accessed by art conservators everywhere. He's collaborated with photo conservators at leading museums and libraries to gather data on the prints in their collections.

Lundgren, at the Library of Congress, was drawn to Messier's method because of doubts she had about the authenticity of particular photographs in the library's collection. The series in question is called "The Seven Words," depicting the seven last words of Jesus Christ, by the early 20th-century American photographer F. Holland Day. By analyzing paper texture, among other attributes, Lundgren was able to figure out that one set of prints had been made by a photographer who had re-photographed original Day prints then created a new negative and new prints.

"When we look at Day's work in our collection, the image is right, but the prints were made 13 years later and they weren't made by Day," Lundgren says.

The Museum of Modern Art in New York City has also focused on methods and techniques of materials characterization, expanding on Messier's approach, but in a different direction — to reveal trends and relationships in a particular period in photographic history. In 2009, the museum began analysis of 341 modernist prints from the interwar period. The work resulted in the creation of an online database in which users can create visualizations of relationships between photographers and compare photographs based on dozens of attributes like the use of a technique called ferrotyping, or whether different types of retouching were involved in the print creation. In some cases, MoMA was able to draw some surprisingly intimate connections.

"There were lots of examples with nearly identical fiber analysis, and it turns out [the two photographers] were very involved with each other and were working in the same darkroom, using the same box of paper," says Lee Ann Daffner, a conservator at MoMA who led the work.

Altogether, Messier's techniques have introduced a dramatically new way of seeing into the world of photography conservation. The implications of this perspective are only just beginning to be explored, and they're sure to go far beyond calling out impostor prints. Although, speaking of the suspicious photographs that got Messier started on this work in the first place — Lewis Hine died in 1940, and the prints in question turned out to have been made on paper that didn't become available until the 1960s.