This won’t hurt a bit

Ultramodern technology finds a place at the Oriental Institute.

By Benjamin Recchie, AB’03

oi-laser.jpg

I confess that when I was told about a special tour of the Oriental Institute involving “death rays” and ancient artifacts, arranged by William Harms of the University’s News Office for the Chicago Science Writers, I couldn’t help but think about Stargate: SG-1. Upon closer inspection, though, it became clear that this event would have a lot more to do with conserving artifacts than with Richard Dean Anderson. So much the better.

Emily Teeter, PhD'90, research associate at the OI, met our group, accompanied by lab-coat-clad conservators Laura D’Alessandro and Alison Whyte. (“We brought out our good lab coats for this,” confided Whyte.) Teeter led us to the Objects Conservation Lab, where the conservators preserve the artifacts in the OI’s collection. Some artifacts, having been buried for millennia, start to decay upon being unearthed; some decay because of clumsy restoration projects of an earlier generation. Others are coated with pollution from being stored in OI rooms open to the soot-filled Chicago air of the early 20th century. In short, said D’Alessandro, “If they think that something looks unhealthy, they call us.”

The science writers’ interest in the lab rested in the high-tech equipment the conservators use to preserve the past. Whyte uses a scanning electron microscope in the Department of Geophysical Sciences to determine if an artifact has “bronze disease,” a kind of corrosion that can occur when a previously buried artifact is exposed to the air. It’s usually obvious if the fluffy green detritus on the object is bronze disease. However, the treatment is invasive, so the conservators avoid it if there’s any suspicion that it might actually be something else. The microscope can reveal the presence of molecules that make their diagnosis certain. Whyte also uses the electron microscope for investigations; she and Teeter showed a pair of ancient Egyptian makeup palettes that still had cosmetic residue on them; the microscope’s scans revealed the makeup’s exact chemical, uh, makeup.

Then we came to the “death ray," a hand-held infrared laser designed for museums. Called the Compact Phoenix, it vaporizes the top few microns of any residue on an artifact. (See this video of the device in action in Britain.) D’Alessandro explained that each flash of the laser (which, in fact, did faintly resemble a Star Trek phaser) lasts only a fraction of a second, short enough that the all of the beam’s heat is carried away by the vaporized surface material, and none transferred to the artifact. The beam isn’t powerful enough to cause users serious injury (except blindness—the conservators wear heavy-duty protective eyewear when the laser is active). The laser is usually used only when traditional conservation methods have failed, D’Alessandro explained. To demonstrate, she showed a video of the laser being used to remove debris from a strand of fragile, millennia-old Nubian rope.

Last-ditch surgery is far from the lab’s only trade. Teeter consults with the conservators when choosing artifacts for an exhibition, such as the upcoming “Before the Pyramids: The Origins of Egyptian Civilization.” They can tell her if something is too fragile to be displayed, and sometimes they even suggest a replacement.

The science writers were full of questions. One, referring to the artifacts in front of them, asked how the conservators arrested the aging process. Teeter gestured to her face and joked, “Well, I use cream.”

March 17, 2011