'That, to me, looks like Egyptian blue," Lynn Grant said as she scrutinized a painting on mud plaster from more than 3,100 years ago.
Colleague Molly Gleeson agreed, but was curious why tests showed that the paint contained iron - not a standard ingredient in the ancient blue pigment.
A typical interaction for members of the conservation staff at the University of Pennsylvania Museum of Archaeology and Anthropology - with one exception. They were leaning over their microscope in full view of the public.
The Penn Museum recently opened the new artifact lab in an airy, light-filled space on its third floor, surrounded by a glass wall for easy viewing by museum-goers. Someone is always on duty analyzing, cleaning, or mending precious mummies and other Egyptian items from the museum's collection, and twice a day the conservator opens a window to field questions from anyone who happens by.
Public science is all the rage as museums strive to engage a new generation of visitors. In recent years, the Brooklyn Museum, the Smithsonian's Lunder Conservation Center in Washington, D.C., and the Museum of Fine Arts Boston all have built conservation labs that are open to public view. Some of the natural history museums have been at it much longer, notably Philadelphia's Academy of Natural Sciences of Drexel University, with the fossil prep lab that opened in the late 1990s.
In the new lab at Penn, most of the 30 items now on display had been hidden away in storerooms of the museum, which is celebrating its 125th anniversary this year. (The celebration culminates on Dec. 6, when the museum will unveil an interactive map and timeline featuring 125 of its far-flung expeditions.)
Many of the objects in the artifacts lab pose some kind of mystery, and were chosen because scholars were eager to take a closer look, said David P. Silverman, curator in charge of the Penn Museum's Egyptian section.
"The whole idea was to include not only what we wanted, but also what we knew the public would be interested in seeing," Silverman said.
With the mud plaster painting, the unknowns include the name of the man depicted, and whether the work is entirely authentic. Unlike most of the more than 40,000 items in the museum's Egyptian collection, the painting was not excavated by scientists, but was purchased in 1925 from a dealer, so information on its origins is scant.
It depicts a man of the elite class holding an ankh - a cross with a loop that represents life - in his right hand. Silverman has vague misgivings about the work, in part because of the man's angular form. He thinks perhaps it is authentic, but was touched up or "enhanced" long ago by someone with an inexpert hand.
The atypical iron in the blue paint was revealed with a technique called X-ray fluorescence, said Gleeson, the project conservator. The blue pigment also contained the usual copper.
"I need to do more research into what we should be seeing," Gleeson said.
Other items lying on tables in the lab include mummies, wrapped and unwrapped, intact and not so intact. Several consist of just the heads, the expressions on their walnut-brown faces frozen in time.
Gleeson said the most popular query from visitors is whether the mummies are real. Sure enough, that question came from a group of home-schooled children who were visiting on a recent weekday.
Among the mummies is a 5-year-old girl, named Tanous. Her name is written on the wrappings in two languages. One is Demotic script, a form of writing that was used during the later years of ancient Egypt. The other language is Greek - tau alpha nu omicron upsilon sigma - reflecting Greco-Roman influence in the region.
A CT scan of the mummy confirmed the girl's gender and also revealed gold bangles on one wrist, said Grant, the museum's head conservator.
"That's a sign of affluence, that you could afford to dedicate that much gold to the afterlife," Grant said.
The public question sessions are held Tuesdays through Fridays at 11:15 a.m. and 2 p.m. for half an hour, and on Saturdays and Sundays at 1 p.m. and 3:30 p.m.
When the conservators are at work on an object and cannot talk, visitors still can see what they are doing through the glass wall. In addition, any time an item is under observation on a microscope, the image also is displayed on a giant screen, visible to all.
This being the 21st century, the conservators also are engaging with the public in another way, via a blog at http://penn.museum/artifactlab. The lab was funded by a donation from Wharton graduate John R. Rockwell, a member of the museum's board of overseers, and his wife, Frances.
One of the larger items is a 4,000-year-old wooden coffin that held the body of Ahanakht, a provincial governor.
Conservators have examined it using ultraviolet light, in order to bring out some details in the faded painting on the coffin's surface. Silverman, the curator, looks forward to translating some of the spells inscribed on the wood.
The wooden boards were the subject of a more well-known scientific analysis in 1952. Willard F. Libby used a chunk from the coffin to help validate his radiocarbon dating method, for which he won the 1960 Nobel Prize in chemistry. The date of the coffin was known from historical records; Libby was able to match that date by analyzing the wood to determine the rate of decay of the isotope carbon 14.
"This is the history of archaeology, big time," Grant said.
Who can say whether the conservators' new efforts will yield a scientific discovery of equal proportions?
But if they do, it seems that it will happen in the public eye.