In the 1990s the market for photos exploded. As snapshots started selling for millions of dollars, sham photos also slipped into the fray before the art world had any way to authenticate originals.
And so cultural heritage researchers had to play some serious catch-up, and quickly.
That’s the gist of my recent cover story on photo conservation. It explores how two fraud cases helped turn the field from a niche research area to a mature science.
And as always happens when reporting, many cool tidbits didn’t fit in to the final piece… In this case, the pivotal role eBay played to help researchers develop ways to catch fakes.
But first, a bit of background on photo fraud:
In the photo market, people will pay more money for an image when it was actually printed on paper by the photographer himself or herself. The price can also increase when the print is older.
So, for example, the Getty Conservation Institute’s Art Kaplan told me that an Ansel Adams photograph printed in the 1920s can sell for hundreds of thousands of dollars, while the exact same photograph printed a few decades later (say, the 1970s) can sell for just tens of thousands of dollars.
It turns out that researchers wanting to authenticate a photo spend a lot of time scrutinizing the paper on which it has been printed, because photo paper generally provides the best dating and provenance clues.
For example, researchers look for chemicals called optical brighteners which were added to all photo paper to brighten images starting in the 1950s. If a photo is purported to have been made earlier than the 1950s, then it can’t have any optical brighteners in the photo paper.
Likewise, in the 1880s, companies started adding a so-called baryta layer to the top of photo paper as a physical barrier between image and paper, so trace impurities in the paper wouldn’t leach into the image layer and wreck the picture.
Each company used a different ratio of barium and strontium in the baryta layer, and companies also changed these ratios over time. Since most photographers were loyal to a particular photo paper brand, authenticators check to see whether a suspect photo has barium and strontium ratios that correspond to the photographer’s preferred company during the era when the photograph was supposedly printed.
Of course to make these comparisons, you need an enormous database of reference photo paper, says Paul Messier, a photograph conservator who helped develop ways to authenticate Lewis Hine prints in one of the world’s first million-dollar photo fraud cases.
“A switch flipped on when I was working on the Hine project,” Messier says. “I realized that there needs to be a reference collection and that it didn’t exist. So I very aggressively began collecting papers.”
But where the heck do you get examples of Kodak or Agfa paper from the 1930s or 40s or 70s? Many companies specializing in traditional photo printing paper have gone out of business as people have turned to digital photography. And many photo paper companies don’t have archives of every batch of paper they produced over the past century.
The answer, of course, is eBay.
The online market helped Messier create an archive of over 5000 different samples of photo paper from the 20th century. The folks at the Getty Conservation Institute also told me they buy old photo supplies on eBay. (Public donations have also beefed up reference collections.)
After examining innumerable samples of photo paper from his collection under a microscope, Messier came up with yet another promising way to authenticate photo paper: By analyzing surface patterns.
Messier began noticing subtle differences in textures of photograph paper from one manufacturer to another, and within manufacturers, over time.
Now he’s now working with researchers at the Museum of Modern Art in New York, and a team of signaling processing experts to come up with a way to identify a paper’s source from its surface texture alone.
The idea, Messier says, is to “show the system an unknown texture. It would go through its database of identified textures, and it would say, that’s a Kodak F surface from the 1950s.” Then researchers could check whether a photographer used Kodak F surfaces on other prints.
It’s another authentication tool made possible through eBay.
Incidentally, eBay is a boon to other areas of cultural heritage science too. The online market has enabled everything from Picasso paint analysis to modern plastic artifact research.
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