Mercury In Platinum Prints Makes Things Sepia–Or Does It?
Around 1889, Gertrude Käsebier, a 37-year-old, unhappily married mother of three, decided to go to art school.
A decade later, around 1900, Käsebier’s photo studio in New York City was so successful that her platinum print portraits were “the thing to have,” in turn-of-the-century socialite circles, says Tram M. Vo, an independent conservator who has been collaborating with Dusan Stulik at the Getty Conservation Institute.
“At the time, photographers charged about $12 for 12 prints,” Vo says. “Käsebier charged people $25 just to sit for a photograph and $5 for a single print.”
There’s not a lot known about Käsebier’s techniques in the dark room because she didn’t leave many notes behind. So Vo is trying to learn about her methods using an analytical technique called X-ray fluorescence spectrometry (XRF). Conservation scientists use XRF to get a list of the chemical elements present in an artwork using X-rays—all without touching or destroying the artwork.
In particular, Vo wants to learn more about the so-called sepia look in many of Käsebier’s prints. Sepia is the word used to describe when black and white photographs have a brownish tint that gives the shots a warm feeling.
In today’s digital world, giving a photo a sepia look is just a Photoshop click away. But when Käsebier wanted to give her platinum prints the sepia look she had to use dark room chemistry.
Photo history experts have long thought that if a photo from that era had a sepia look, it probably came by means of a few drops of a mercury bichloride, added during the development process. Vo is finding that this might not always be true.
Vo used the XRF to look at the elements in Käsebier’s sepia-looking photographs. She found that some of Käsebier’s sepia prints had no mercury present, and thus the warm tones must have come from a different process—but what?
It’s possible that Käsebier sometimes got the sepia look from iron found in development solutions, Vo says. Normally the iron would be rinsed off the print during the development process, but if the iron was left behind, it could break down cellulose in the paper over time, which would add a sepia tinge to the prints.
Vo also used XRF to look at Käsebier photographs that didn’t have the sepia look, and was surprised to find mercury on non-sepia black and white prints. Käsebier must have used mercury in other dark room processes, but it’s not clear yet which ones. Obviously there’s more fun photo-forensic work left to be done to completely understand Käsebier’s techniques.
Even though Käsebier used mercury regularly in the darkroom, which is not precisely the healthiest thing around, “the exposure didn’t seem to hurt her,” Vo says. She lived til the ripe old age of 82, producing some 100,000 negatives (wow!) during her lifetime.
This is impressive given how late she started her career… which was also back in the day when professional photographers worked hard to get a single quality shot, instead of shooting hundreds at a time with a digital camera.