Flattery for Faience Imitating ancient materials reveals lost

manufacturing secrets By JESSICA GORMAN

’ hile students swarmed the halls at the Massachusetts Institute of Technology one Friday late

last November, a dozen or so outsiders crowded into a small glass shop in the basement of Building 4. They were reca- pitulating the first steps of an ancient art. Standing around a workbench, their hands dusty and gray, the group listened to Carolyn Riccardelli, who gingerly pat- ted at a pasty mixture that had the con- sistency of wet toothpaste.

Riccardelli, a conservator at the J. Paul Getty Museum in Los Angeles, was show- ing the group of materials scientists, ar- chaeologists, and conservators how to formulate and mold an ancient Egyptian material known as faience. It’s a type of ce- ramic with a quartz core and glazed sur- face. A well-known example is an %inch- long, bright-blue hippopotamus at the Metropolitan Museum of Art in New York.

Leaders of a symposium on the materi- als-related aspects of art and archaeolo- gy at a national meeting of the Materials Research Society (MRS) in Boston had brought attendees to the MIT shop to let them literally get a feel for how the ancient material was made.

Using a spoon, Riccardelli patted the delicate paste into a clay mold. When the amateurs tried their own hands at this technique, they quickly realized that just a little too much or too little water made the material fall apart. It sometimes took several tries to mold a simple shape, such as grapes. “This is why we look at ancient faience and we go ‘How did they do that?”’ Riccardelli says. “It’s difficult to work with.”

It’s also worth the trouble, she says. Scientists and cu- rators can achieve an un- derstanding of ancient ma- - terials and cultures that would be impossible with- out getting their hands dirty, Riccardelli argues. For this reason, many re- searchers-such as those at the MIT workshop-

An ancient funerary figurine of Egypt’s King Nectanebo II is made of carved faience.

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have become increasingly interested in gaining a craftsman’s knowledge of ma- terials processing. With this approach, Riccardelli and other researchers have revealed fine details of faience manufac- ture and composition that were lost for thousands of years.

ncient Egyptians began making faience more than 6,000 years ago, and archaeologists have studied it

intensely in the past century. Even so, new work using powerful microscopy and spectroscopy techniques continues to uncover long-lost secrets about the faience industry. Researchers including Riccardelli, however, have been showing that another fruitful way of demystifymg ancient arts is to replicate them. Her mot-

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to could be, To make faience is to under- stand it.

“The Egyptians didn’t leave recipes, so we really don’t know how they made things,” says curator Rita Freed of the Museum of Fine Arts, Boston. “The only way we can find out is when people try to replicate things . . . . That way we can understand just how much skill is in- volved, how much science is involved, and how sophisticated the whole process was.”

Ancient Egyptians prized objects such as beads and vessels constructed from faience, probably because the surfaces look like gemstones. Made mostly of sili- ca, from such sources as quartz and sand, faience usually contains several other components: calcium carbonate, a water-soluble alkaline substance such as sodium bicarbonate, and a chemical col- orant. Copper oxide, for example, gives faience a distinct blue color reminiscent of lapis lazuli.

One common method of faience prepa- ration-which Riccardelli uses in her re- search and demonstrated at the MIT workshopincludes a technique called efflorescence glazing. In this process, the faience maker mixes the ingredients to- gether with a little water and then pats, taps, and molds the paste into shape. As the material dries, the colorant and water-soluble salts move to the surface and form a crust. After the material is

completely dry, it’s heated in a kiln. This creates a glossy, colorful

A day before the work- shop, Riccardelli spoke at the MRS meeting about how ancient Egyptians of- ten inlaid pieces of differ- ent colors into one other. “It’s just some of the most gorgeous colored stuff in faience,” she says.

While studying faience inlay, Riccardelli had wondered how ancient people managed to cre- ate certain fine details. She says that the arti- sans’ creation of such exquisite inlaid objects shows that they had clear knowledge of

coating.

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Salts effloresce (white crust) on the surface of wet faience paste that has been shaped in clay molds. After firing to 900°C, the faience objects develop a blue glaze.

how the materials behave in different sit- uations.

She became particularly curious about two aspects of faience inlay: First, cer- tain objects with inlaid designs-like the petals in a flat rosette-contain a distinct glazed layer under the inlay. Second, many objects have a separation between the inlay and the background piece. She wondered what skills and procedures are necessary to make the glazed layer or separation lines.

Several years ago, she began a system- atic study to determine what procedures the ancient Egyptians could have used to produce the distinctive details. Making her own pastes, Riccardelli tested a mul- titude of techniques in an attempt to replicate ancient rosette designs. For ex- ample, she inlaid wet paste petals on a wet rosette background, dry petals on a wet background, and wet petals on a dry background. She also fired dry petals and backgrounds in the kiln and then in- laid wet paste petals on the fired back- grounds. In another approach, she put fired petals into wet backgrounds before the entire rosette was fired.

After each attempt to replicate the an- cient inlaid faience, Riccardelli used mi- croscopes to examine her wares’ sur- faces and cross sections of broken pieces. She then compared the results with observations she made on 60 frag- ments of ancient faience objects in muse- ums in London, New York, and Boston.

Riccardelli found that two of the inlay- ing procedures she tried replicated the glazed layers of the originals particularly well. In one case, she allowed the back- ground to dry completely and then added wet paste for the petals. In the other case, she fired the dried back-

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ground before adding wet paste. Although confident that she’s replicat-

ed the glazed layer she’s seen in many ancient objects, Riccardelli is continuing to look for a procedure that more exactly produces the separation lines between inlaid and background pieces.

Some researchers had previously sug- gested that the lines formed sponta- neously as two differently colored faience pastes dried, shrank, and pulled away from each other. But faience pastes don’t shrink enough to produce the ob- served pattern, Riccardelli contends. In practice, Riccardelli has found that the lines aren’t easy to make, and she sur- mises that they didn’t form accidentally.

Riccardelli is the first person to show how to inlay and glaze objects in a way that replicates certain details seen in many artifacts, says Jennifer Mass of the Winterthur @el.) Museum, who was an advisor for the project while Riccardelli worked on it as a student at State Univer- sity College at Buffalo in New York. Ric- cardelli later took her project to the Get- ty Museum and has since moved on to the Metropolitan Museum of Art.

“I thought everything about faience was known and done,” symposium organ- izer Pamela Vandiver, a materials scien- tist at the Smithsonian Center for Materi- als Research and Education in Suitland, Md., told the audience before Riccardelli presented her results at the MRS meet- ing. “She’s blown a lot of us away.”

atricia Griffin of the Cleveland Museum of Art is another investi- gator probing still hidden tech-

niques behind ancient Egyptian faience-and using replication experi- ments to do it.

Griffin wanted to identify the composi- tion of individual faience objects in her museum’s Egyptian collection and the processes that were used to make them. Although she sought this information to better understand and catalog the muse- um’s objects-many details of which were published in a 1999 catalog-she was also personally interested in a big- ger picture.

Griffin wanted to know how and why similar items from different periods vary in their details. For example, did faience paste composition change ever so slightly, permitting better handling and more precise detailing in the later of two sets of similar objects made 700 years apart?

Signing up for space in night ceramics classes at the Cleveland Institute of Art across the street from her museum, Grif- fin began to experiment with different compositions for faience paste. She tried varying the chemistry and the coarseness of the paste. She also com- pared how easily each mixture could be handled, molded, and cut with instru- ments.

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Griffin then analyzed the structure and composition of her modern faience ob- jects using advanced instrumental tech- niques, such as scanning electron mi- croscopy and X-ray fluorescence spectroscopy. With the results of these analyses-performed at the museum and at nearby Case Western Reserve Uni- versity and the NASA Glenn Research Center, both in Cleveland-Griffin used her handmade objects as standards against which to compare similarly ana- lyzed samples from the Cleveland Muse- um of Art’s collection.

At the MRS meeting, she reported that the composition and manufacturing of the objects in the collection did in fact vary over the centuries. For example, lat- er artifacts, such as a funerary figurine from about 350 B.C., are remarkable both in their detail and craftsmanship. They contain more calcium and their pastes consist of smaller particles than objects from 600 to 700 years earlier, which show less detail.

The ancient artisans probably added the calcium in the form of calcium ox- ide-burnt lime-rather than calcium carbonate, or limestone, Griffin suspect- ed. This would give the paste the consis- tency of plaster, she says. And by trying out new recipes, Griffin found that it was easiest to mold and carve objects into their final shapes when the paste is fine and contains higher concentrations of calcium added as lime.

This rosette’s background (blue) dried before petals of wet paste (white) were inlaid. Before the petals could dry, the entire rosette was fired in a kiln. A cross section shows the layer of glaze that formed beneath an inlaid petal.

aterials science has long been part and parcel of the study of M ancient objects. Indeed, art and

archaeology has been part of the agenda of Materials Research Society meetings

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for many years. Last November’s sympo- sium on art and archeology, however, was the first occasion when organizers invited craftspeople to participate.

“It’s the first time we’ve put together craftsmen with scientists with archaeolo- gists and art historians,” says Vandiver. Craftspeople, she says, know how to process materials, and they’re particular- ly insightful about how those materials behave and respond under many differ- ent conditions.

Consider glassmaker Dudley F. Giber- son of Joppa Glassworks in Warner, N.H. At the symposium, he explained how he makes replicas of a small jar called an Egyptian-style core vessel. He carefully coats a vessel-shaped object made of clay, sand, sawdust, and dung with pow- dered glass, called frit. The frit-coated ob ject is heated in a furnace for a few hours until the frit partially fuses. Then, Giber- son holds the object directly over a heat source to add glass handles, rims, and other decorations. After the vessel cools, he digs out the core.

Giberson’s glass vessels closely resem- ble some ancient artifacts, down to tiny bubbles visible only with a microscope, notes Vandiver.

While Riccardelli taught faience inlay

techniques in the MIT basement, Giber- son simultaneously demonstrated his painstaking craft in the same shop. “One thing I’ve realized is that the Egyptians had plenty of time,“ he says.

The MIT workshop was more than just a diversion for conference-weary scientists. Replication is increasingly a part of how archaeologists go about their research, reiterates Freed. “The idea of archaeology is to reconstruct the life of ancient man or really to bet- ter understand ourselves in a way,” she says. Undertaking the actual physical actions and procedures ancient people used for making real things is one way to do this.

Vandiver adds that many archaeolo- gists abide by the maxim that they need to understand the entire lifetime of an ar- tifact, including its transformation from raw materials.

“When you find an artifact. . . you want to get back to when it .was not just an ar- tifact dug up, but when it was actually an object working in a culture,” she says. “Then, you want to work your way back to the raw materials that actually formed that object.”

Sometimes making an object can quickly reveal a long-hidden technique.

Ancient artisans created this unglazed Egyptian object, a cosmetic jar in the form of the god Bes, with molding, modeling, and carving techniques similar to those used to make faience.

“You don’t really get it until you get that material in your hands,” says Riccardelli. “You can come up with all kinds of ideas, but then you should try it. A lot of ques-

0 tions get answered really fast.”

Biomedicine

Cancer fighter reveals a dark side Too much of a good thing can be bad, even when it comes to

a tumor-suppressing gene. Researchers report that mice with an overactive gene for a protein called p53, which checks inap propriate cell division and helps prevent cancer, prematurely suffer agerelated conditions such as osteoporosis and die ear- lier than normal. This raises the prospect that there’s a trade off between tumor suppression and a long lifespan.

Lawrence A. Donehower of the Baylor College of Medicine in Houston and his colleagues were trying to produce mice with a disabled p 5 3 gene when they accidentally created a mouse strain in which the gene is overactive. Mice lacking the p 5 3 gene are cancer-prone, so it isn’t surprising that the new mutant strain is much less likely than normal to develop tumors.

Despite the enhanced cancer protection, the mutant mice die earlier than normal. The median lifespan of the mutant mice is 96 weeks, whereas normal mice have a median lifespan of 118 weeks, Donehower’s team reports in the Jan. 3 NAIVE.

The researchers couldn’t find any common cause of death in the mutant mice, so they wondered whether the animals suffer from accelerated aging. Further investigation proved that hunch to be right, revealing that these mice develop os- teoporosis, impaired wound healing, muscle weakening, organ atrophy, and other agerelated conditions much earlier in their lives than rodents normally do.

The mutant mice didn’t age faster in all ways, however. For example, cataracts, joint diseases, and hair loss were not more common in the mutant mice than in normal mice of the same age. Donehower and his colleagues speculate that the condi- tions seen in the mutant mice result from a p53-mediated re- duction in the ability of unspecialized cells to proliferate and keep tissues healthy.

The results “raise the shocking possibility that aging may be a side effect of the natural safeguards that protect us from can-

cer,” Gerard0 Ferbeyre of the University of Montreal and Scott W. Lowe of Cold Spring Harbor (N.Y.) Laboratory in a commen-

-.I. z tary accompanying the research report.

Cloning’s ups and downs There’s been good news and bad news about cloning of late.

On the worrisome side, one of the creators of Dolly, the world‘s first cloned mammal, report that the nearly 6-year-old sheep has developed arthritis in her left hip and knees. That’s early for a sheep to show such a malady, and the report renews con- cern that cloning may accelerate aging (SN: 4/29/00, p. 279).

There’s no way to confirm that the arthritis is attributable to cloning, cautions Ian Wilmut, one of Dolly’s cloners at the Roslin Institute in Edinburgh. Still, he calls upon other cloners to monitor the longterm health of their animals.

Now the good news: In an advance that one day may help people needing transplants, two biotech firms have turned to cloning in their attempt to create pigs with organs that human bodies won’t reject. Using nonhuman organs such as pig hearts and kidneys in people is the basis of a controversial strategy known as xenotransplantation.

One barrier to this approach has been that pig cells sport a sugar molecule foreign to the human body, so a person’s im- mune system would quickly reject the animal tissue. To over- come this, scientists have struggled to create pigs in which the gene for the enzyme that makes the sugar doesn’t work.

In the Jan. 4 SCIENCE, investigators from Immerge BioThera- peutics in Charlestown, Mass., and the University of Missouri in Columbia report disabling one copy of the gene in pig cells and using the cells to clone a litter of piglets bearing the nonwork- ing gene. Since pigs have two copies of the gene, the scientists now are interbreeding the litter to create swine with both genes deactivated. Meanwhile, PPL Therapeutics, the Scottish compa- ny that funded Dolly’s creation, has announced that it also has

-.I. I: cloned pigs with one disabled copy of the gene.

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