When priceless photos from the early days of photography faded before the eyes of visitors to the exhibition, a surprising team formed to save them
Black and white ghosts of the "Boston Brahmins", wealthy New Englanders in the middle of the 19th century, watched their viewers through the glass panes and the black rosewood frames that hung in the darkness of the International Center of Photography in New York. These were the works of Albert Sands Southworth and Josiah Johnson Hawes, the "Rembrandts" of daguerreotype photography - the first practical form of photography. A pious bride in a white silk mullet twirls the ribbons of the cloth with her fingers. The arrogant and severe statesman Hasbar Daniel Webster looks through his eyebrows. The 150-year-old photos, presented in the "Young America" exhibition that opened in 2005, captured the symbols of that era, when the American nation was in the process of transitioning from adolescence to becoming a world power. "Each picture glows on the wall like a stone in a mood ring," the New York Times said in an article reviewing the exhibition.
However, after a month of display, the figures on the silver plates began to fade. White spots spread across half of a portrait of a woman in a skirt as long as a curtain. Multicolored halos formed over the picture of Henry Ingersoll Bowditch who advocated the abolition of slavery. At the end of an exhibition of two and a half months, 25 daguerreotype pictures were damaged, five of them severely.
The sudden weathering caused panic among the small community of degrotype enthusiasts. Unlike photography where one negative allows to create many prints, each daguerreotype image is unique and special. Once an image fades, it is lost forever. The disappearing portraits raised the possibility that any daguerreotype might spontaneously disintegrate. Collectors feared they were about to lose collections worth millions of dollars. Preservationists feared that these windows, into the 19th century, were simply about to cloud over forever.
At the time, art conservators and daguerreotype experts had no idea what might be causing it. Although most of the pictures were kept, during their years, in the dark vaults of the George Eastman House, the International Museum of Photography and Cinema in Rochester, New York, occasional exhibitions do not seem to have done any harm in the past. This time, the mere display of the images seemed to cause them to collapse. The Eastman House has decided to stop displaying its daguerreotypes. New York's Metropolitan Museum of Art currently displays only one daguerreotype hidden in a curtain. And the Yale Center for British Art has postponed a major planned exhibition of daguerreotypes until conservationists can find a safe way to display them.
And the task of finding such a way was placed on the shoulders of Ralph Wiegandt, a conservation expert at the Eastman House who designed the lighting and display cases for the "Young America" exhibition. Vigeandt, a friendly and stubborn man with the curiosity of a craftsman, found himself faced with complex chemical questions that were outside his area of expertise. "I've been in conservation for almost 30 years, and these objects are different from everything else," he says. "All of their existence lies in one or two molecular layers." The complicated physics of the surface of the silver plates in daguerreotypes therefore required extraordinary collaboration.
Wiegandt needed the help of physicists. And during their journey to understand why the images fade, he and his colleagues discovered surprising molecular phenomena at the nanometer scale. These random remnants of 150-year-old technology may therefore inspire the engineers of the future.
Fixed images
Nicholas Bigelow is the head of the physics department at the University of Rochester down the road from Eastman House. He heard about the original exhibit, and in 2009 invited Wiegandt to present his unique problem in a lecture at a physics conference held in Rochester. Bigelow usually deals with Bose-Einstein condensates, opaque clouds at temperatures close to absolute zero immersed in an unusual quantum state and under conditions that are difficult to imagine. Nevertheless, Vigeandt's lecture won his heart and he offered him his services. He explained this by saying that he wanted to help "with something that has an impact on the human side of life."
Bigelow realized that daguerreotypes changed the way we see the world. Louis-Jacques-Mande Daguerre, a Parisian artist and theater man, introduced the method in 1839 after ten years of searching for a way to fix an image on a silver plate. It is said that one day he accidentally broke a mercury thermometer and absent-mindedly placed it in the cupboard where he kept his silver plates. The next day he discovered that the mercury vapor had somehow fixed the images on the plates. Degar discovered the chemistry of creating a photograph. "What really happened there was the self-organization of nanostructures," says Bigelow. "Even if he didn't mean it, he was involved in nano-engineering."
Bigelow and Wiegandt had to recreate the nano-engineering that Deguer had encountered (of which he had never been aware). But before that they had to perform some macro-engineering operations. On an unusually warm day in February, Vigeandt, Bigelow and Brian McIntyre, a microscopy expert at the University of Rochester, knelt on the floor of the physics department and pounded the handle of an electron microscope hammer. The vacuum chamber valve was "problematic" and needed a few strokes. When the valve finally worked, the computer screen showed a square of silver, a few centimeters long, placed in the empty chamber. It was a piece of daguerreotype that Wiegandt bought on eBay for $60 and cut into squares. On the surface half the face of a man with blurred eyes was visible. “I know I cut this gentleman. I take the blame on myself," Vigeandt told me.
Magnified 32 times, the man's face looked like a map from the 19th century. The weathering in his hair looked like an oil slick in the ocean and the bubbles like a group of islands. At a magnification of 20,000 times, the sanded surface of the silver was seen to be furrowed in the direction of the sanding. The brightest areas, like the white parts of the man's eyes, revealed hidden nanostructures that resembled tiny clusters of egg whites: uniform silver-mercury crystals whose density on the board determined where the white areas would be and where the gray areas would be.
Making a daguerreotype requires three steps. First, the artist exposes a silver plate to iodine or bromine vapors, two very active elements from the halogen family. The vapors react with the silver and form a uniform, light-sensitive layer of iodide or bromine silver. When the photographer exposes the plate to light, the photons remove the iodine or bromine atoms, leaving pure silver. In the dark areas, the silver halide compound remains. In the next step, the artist exposes the board to mercury vapor. The mercury atoms bind to the pure silver and form silver-mercury crystals. In the last step, the artist washes the board with a solution of sodium thiosulfate, which the photographers call "Hypo". The solution removes the halogens and leaves a plate of pure silver with spots of silver-mercury crystals on it. The pure silver looks black and the silver-mercury crystals look white. This creates a strange looking effect: the figure appears to be beaming through the silver plate's mirror-like surface.
Because of the silver's tendency to react, the hagrotypes always tended to get stained. The creators of the portraits therefore always made sure to immediately seal the panels in glass boxes to protect them. This method worked well for 150 years until the "Young America" exhibition proved that they were sensitive to light.
bright spots
Vigeandt and Bigelow worked to solve the problem with conservation experts from the Metropolitan Museum who found traces of chlorine in the white weathering spots that appeared on the photos. Because the panels were originally exposed to Boston's salty air, chlorine ions penetrated the panels. Chlorine is a halogen, like iodine, and reacts with silver. A spotlight focused on a daguerreotype displayed in the exhibition can re-expose the plate and create silver chloride crystals that will cloud the original image.
But the sea air is not the only culprit. Vigeandt and Patrick Ravens, now director of the art conservation department at Buffalo State University, found that the integrity of the hagrotypes was also compromised beneath the surface of the panels. Working with researchers at Kodak, and using a focused ion beam, Wiegandt's team punched a 30-micron-long square hole through the surface of daguerreotypes selected as an example. Then they examined the cross-sectional layers. To their amazement, they discovered cavities with a diameter of 300 nanometers just below the surface that created a network of tunnels under the image.
The team believes that this phenomenon, caused by exposure to light, is due to the "Kirkendall effect", which usually occurs in metal alloys. When two different metals are separated and mixed with each other at different rates, cavities or small defects are formed on their surface. The voids in the degrotypes were probably formed when they were first exposed to light and the silver-mercury crystals attracted silver atoms below the surface.
The spaces may explain why some of the hagrotypes in the exhibition were damaged. Over the course of 150 years, chlorine, or other pollutants, may have seeped into these spaces. When the pictures were shown in the exhibition, the light triggered chemical reactions under the surface between the chlorine and the silver and so the stains popped up from below and destroyed the pictures.
However, from the positive aspect, the discovery may help in other fields of industry. Many researchers are looking for ways to produce uniform hollow particles that could, for example, contain drugs. Bigelow believes that if the team finds a way to control the Kirkendall effect to produce single, uniform holes in metal particles, the method could be used to design medical nanocapsules.
Sealed frames
Wiegandt cannot repair the damage already done to the pictures, but he can use the knowledge he has acquired to protect the remaining pictures in the Southworth and Hews collection. In his laboratory at Eastman House he built a prototype for frames made of aluminum and pyrex that could be sealed with a valve in an Argon atmosphere. Argon is a noble gas that protects the hagrotype images from oxygen and other impurities found in the air that may react on the silver surface. He says he was able to lower the cost of the organization box to $50 using "off the shelf" materials.
Wijandt now makes organization boxes for all the pictures in the Southworth and Hews collection held by the museum. However, it is doubtful whether they will be presented to the public again. "I don't know if I can give it a 'green light,'" he says. It's easy to see why a man who has spent the last seven years researching the ways in which the world, from photons to fungi, might destroy the delicate surface of the hagrotype images, would be a little nervous. "In any case, I think that daguerreotype pictures must be kept in an atmosphere of organization, and one is whether they are displayed in an exhibition or stored," he says.
Museum visitors may not appreciate what conservation experts never forget: every exhibit, be it a painting, a stone or a silver plate, has a lifespan. Even in the polished conditions of the museum, painting fades, stone breaks and nanoparticles are released from the silver plate. The guard cannot save them forever. "The two pillars of the museum are preservation and access," says Wijandt. And they have never faced such a tough competition as in this case.
About the author
Daniel Grushkin writes about science and technology in the magazines Business Week, Nature Medicine and more. He is one of the founders of Genspace, a community lab in New York City focused on biotechnology education and innovation.
in brief
Curators of an exhibition of 150-year-old daguerreotypes noticed that the images were blurring before their eyes. The lighting seemed to bleach the pictures and no one knew why.
The conservation expert who was responsible for the images collaborated with a physicist, who usually deals with Bose-Einstein condensations, to investigate the nanoscale chemistry behind the weathering.
The results of their investigation may affect not only a priceless display of art, but also shed light on fundamental physical processes that could be used by nano-engineers.
How does this happen?
Trouble under the surface
A cross-section in a daguerreotype image reveals voids beneath the surface that may cause its condition to deteriorate. When the degrotype image is developed, a chemical reaction occurs on the surface between the silver that makes up the plate and between mercury vapor and gold. Scientists hypothesize that the process draws silver atoms to the surface and creates voids beneath them. In the photographs taken by Southworth and Wess, these spaces may have captured Boston's salty air that contained chlorine. It is possible that re-exposure of the light-sensitive silver chloride may create a haze that spoils the image.
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