Richard Preston - Panic in Level 4

In the wet lab, a team of textile conservators led by a woman named Kathrin Colburn unpacked the tapestries and spread them out facedown on a large table, one by one. At some point, the backs of the tapestries had been covered with linen. The backings, which protected the tapestries and helped to support them when they hung on a wall, were turning brown and brittle, and had to be replaced. Using tweezers and magnifying lenses, Colburn and her team delicately removed the threads that held each backing in place. As the conservators lifted the backing away, inch by inch, they felt a growing sense of awe. The backs were almost perfect mirror images of the fronts, but the colors were different. Compared with the fronts, they were unfaded: incredibly bright, rich, and deep, more subtle and natural-looking. The backs of the tapestries had been exposed to very little sunlight in five hundred years—even, apparently, during the time when they had been used to cover potatoes. Nobody alive at the Met, it seems, had seen the backs of the Unicorn Tapestries in all their richest color.

A tapestry is woven from lengths of colored thread called the weft, which are passed around long, straight, strong threads called the warp. The warp runs horizontally and provides a foundation for the delicate weft, which runs vertically. Medieval tapestry weavers worked side by side, in teams, using their fingertips and small tools to draw the delicate weft threads around the tougher warp. When they switched from one color to the next, they cut off the ends of the weft threads or wove them into the surface of the tapestry. The Unicorn weavers had been compulsively neat. In less well-made tapestries, weavers left weft threads dangling on the back of the tapestry in a shaggy sort of mess, but the backs of these were almost smooth. Kathrin Colburn recalled that as she and her associates stared into the backs of the Unicorn Tapestries, it “felt like a great exploration of the piece.” She said, “We simply got carried away, seeing how the materials were used—how beautifully they were dyed and prepared for weaving.” An expert medieval weaver might have needed an hour to complete one square inch of a tapestry, which meant that in a good week he might have finished a patch maybe eight inches on a side. The weavers were generally young men, and each of the Unicorn Tapestries had likely had a team of between four and six working on it. They wove only by daylight, to ensure that the colors would be consistent and not distorted by candlelight. One tapestry would have taken a team at least a year to complete.

The curator in charge of medieval art at the Metropolitan and the Cloisters is a thoughtful man named Peter Barnet. When he heard about the discovery, he hurried down to the wet lab for a look. He got a shock. “The first of the tapestries—‘The Start of the Hunt’—was lying in a clear, shallow pool of water,” Barnet said. The lab is designed to function as a big tub, and had been filled about six inches deep with purified water to bathe the tapestry. “Intellectually, I knew the colors wouldn’t bleed, but the anxiety of seeing a Unicorn tapestry underwater is something I’ll never forget,” he said. When Barnet looked at the image through the water, he recalled, “the tapestry seemed to be liquefied.” Once the room had been drained, it smelled like a wet sweater.

Philippe de Montebello, the director of the museum, declared that the Unicorn Tapestries must be photographed on both sides, to preserve a record of the colors and the mirror images. Colburn and her associates would soon put new backing material on them, made of cotton sateen. Once they were rehung at the Cloisters, it might be a century or more before the true colors of the tapestries would be seen again. The manager of the photography studio at the Met was a pleasant, lively woman named Barbara Bridgers. Her goal was to make a high-resolution digital image of every work of art in the Met’s collections. The job would take at least twenty-five years; there are roughly two and a half million cataloged objects in the Met—nobody knows the exact number. (One difficulty is that there seems to be an endless quantity of scarab beetles from Egypt.) But when it’s done and backup files are stored in an image repository somewhere else, if an asteroid hits New York, the Metropolitan Museum may survive in a digital copy.

To make a digital image of the Unicorn Tapestries was one of the most difficult assignments that Bridgers had ever had. She put together a team to do it, bringing in two consultants, Scott Geffert and Howard Goldstein, and two of the Met’s photographers, Joseph Coscia, Jr., and Oi-Cheong Lee. They built a large metal scaffolding inside the wet lab and mounted on it a Leica digital camera, which looked down at the floor. The photographers were forbidden to touch the tapestries; Kathrin Colburn and her team laid each one down, underneath the scaffold, on a plastic sheet. Then the photographers began shooting. The camera had a narrow view; it could photograph only one three-by-three-foot section of tapestry at a time. The photographers took overlapping pictures, moving the camera on skateboard wheels on the scaffolding. Each photograph was a tile that would be used to make a complete, seamless mosaic of each tapestry.

Joe Coscia said that his experience with the Unicorn Tapestries was incomparable: “It was really quiet, and I was often alone with a tapestry. I really got a sense that, for a short while, the tapestry belonged to me.” For his part, Oi-Cheong Lee felt his sense of time dissolve. “The time we spent with the tapestries was nothing—only a moment in the life of the tapestries,” he said. It took them two weeks to photograph the tapestries. When the job was done, every thread in every tile was clear, and the individual twisted strands that made up individual threads were often visible, too. The data for the digital images, which consisted entirely of numbers, filled more than two hundred CDs. With other, smaller works of art, Bridgers and her team had been able to load digital tiles into a computer’s hard drives and memory, and then manipulate them into a complete mosaic—into a seamless image—using Adobe Photoshop software. But with the tapestries that simply wouldn’t work. When they tried to assemble the tiles, they found that the files were too large and too complex to manage. “We had to lower the resolution of the images in order to fit them into the computers we had, and it degraded the images so much that we just didn’t think it was worth doing,” Bridgers said. Finally, they gave up. Bridgers stored the CDs on a shelf and filed the project away as an unsolved problem.

ONE DAY IN THE SPRING OF 2003, the distinguished mathematician and number theorist David Chudnovsky and his wife, the United Nations diplomat Nicole Lannegrace, were having lunch at the Bedford Hills estate of Errol Rudman, a hedge-fund manager and a patron of the Metropolitan Museum, and his wife, Diana. Walter Liedtke, the curator of European paintings at the Met, was there with his wife, Nancy, who is a math teacher. David Chudnovsky began talking about digital imagery. Walter Liedtke, who is a Rembrandt scholar, felt a little out of his depth. “I had the illusion that I actually understood what David was saying,” he said. “But this was pearls before swine.” Liedtke decided to put David Chudnovsky in touch with the Met’s photographers. Not long afterward, David, along with Tom Morgan, a PhD candidate who was working with David and David’s younger brother, Gregory Chudnovsky, visited Barbara Bridgers in the Met’s photography studio. Bridgers told them, “I have a real-world problem for you.”