Flattery for faience: imitating ancient materials reveals lost manufacturing secrets - Cover Story

Science News, Jan 19, 2002 by Jessica Gorman

While 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 recapitulating the first steps of an ancient art. Standing around a workbench, their hands dusty and gray, the group listened to Carolyn Riccardelli, who gingerly patted at a pasty mixture that had the consistency of wet toothpaste.

Riccardelli, a conservator at the J. Paul Getty Museum in Los Angeles, was showing the group of materials scientists, archaeologists, and conservators how to formulate and mold an ancient Egyptian material known as faience. It's a type of ceramic with a quartz core and glazed surface. A well-known example is an 8-inch-long, bright-blue hippopotamus at the Metropolitan Museum of Art in New York.

Leaders of a symposium on the materials-related aspects of art and archaeology 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 curators can achieve an understanding of ancient materials and cultures that would be impossible without getting their hands dirty, Riccardelli argues. For this reason, many researchers--such as those at the MIT workshop--have become increasingly interested in gaining a craftsman's knowledge of materials processing. With this approach, Riccardelli and other researchers have revealed fine details of faience manufacture and composition that were lost for thousands of years.

Ancient 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 demystifying ancient arts is to replicate them. Her motto could be, To make faience is to understand 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 involved, 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 silica, 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 colorant. Copper oxide, for example, gives faience a distinct blue color reminiscent of lapis lazuli.

One common method of faience preparation--which Riccardelli uses in her research and demonstrated at the MIT workshop--includes a technique called efflorescence glazing. In this process, the faience maker mixes the ingredients together 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 coating.

A day before the workshop, Riccardelli spoke at the MRS meeting about how ancient Egyptians often inlaid pieces of different 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 create certain fine details. She says that the artisans' creation of such exquisite inlaid objects shows that they had clear knowledge of how the materials behave in different situations.

She became particularly curious about two aspects of faience inlay: First, certain 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 systematic study to determine what procedures the ancient Egyptians could have used to produce the distinctive details. Making her own pastes, Riccardelli tested a multitude of techniques in an attempt to replicate ancient rosette designs. For example, 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 inlaid wet paste petals on the fired backgrounds. In another approach, she put fired petals into wet backgrounds before the entire rosette was fired.