Renaissance painting restoration leads to unusual collaboration

Photo courtesy Cantor Arts Center AFTER RESTORATION

A Cantor Center exhibit from Aug. 4 to Nov. 28 will feature the conserved 15th century painting.

A Renaissance painting is creating unlikely collaborators on the Stanford campus. Experts at the Cantor Center for Visual Arts, the Department of Art and Art History, the Medical Center and even the Stanford Synchrotron Radiation Laboratory (SSRL) are teaming up to use today's technology to understand and preserve yesterday's art treasures. Their project focused on Virgin, Child and St. John by Jacopo del Sellaio (pronounced YA-coh-poh del Sel-LAH-yo), who lived in Florence from about 1441 to 1493.

An exhibition on view at the Cantor Center from Aug. 4 through Nov. 28, Finding Sellaio: Conserving and Attributing a Renaissance Painting, will showcase many facets of two years of study and restoration of the painting. These and similar efforts may allow future generations to enjoy art that otherwise may have been lost to decay.

The alliance of art and science, a model that has been successful in preservation efforts in Italy and elsewhere, could expand to include even more disciplines than those involved in the Stanford project, said Susan Roberts-Manganelli, manager of collections, exhibitions and conservation at the center. "The results are richer when you bring together people who are coming from different perspectives," she said.

The exhibit, curated by Roberts-Manganelli and recent art history graduate Alisa Eagleston, will explain the artist's techniques and the complex process of analysis and restoration, and will include animated 3-D images from a CT scan.

In addition to the Virgin, which is owned by Stanford, the exhibit will feature the Madonna and Child with Infant St. John the Baptist and Attending Angel, a Sellaio piece temporarily on loan from the Fine Arts Museums of San Francisco (FAMSF).

The Virgin is an unsigned tempera on wood. It is a classic devotional image, replete with symbolism -- for example, St. John the Baptist is the patron saint of Florence. The panel presumably was commissioned by a church -- perhaps as the centerpiece of an altar triptych-- or by a confraternity, Roberts-Manganelli said.

The painting dates back to the early 1480s. The Stanford Museum (as the Cantor Center used to be known) acquired it in the early 1970s as a work of Filippino Lippi -- another Florentine painter -- following a 1930s attribution by German art historian and Lippi expert Alfred Scharf. However, the late Harvard art historian Bernard Berenson regarded it as a Sellaio.

This year, Eagleston's undergraduate honors thesis firmly established the painting as a Sellaio. "Pretty much all of our evidence points in that direction," she said.

Participating in the Stanford in Florence program in winter 2003, Eagleston spent long hours in the photographic archives of Berenson's Tuscan villa examining images of the works of Sellaio and Lippi. That gave her a feel for the artists' styles.

Both Sellaio and Lippi were contemporaries and apprentices of the better-known Florentine artist Sandro Botticelli. But Lippi, slightly older, "got more independent more quickly" than Sellaio, Eagleston said.

Eagleston pointed out some telltale signs of Sellaio's artistic style in the Virgin, such as dotted trees with "very stylized, regimented leaves."

"Another thing you can see," Eagleston said, "is the treatment of the figures, which shows the influence of Botticelli" in such traits as the texture and color of hair, the tilt of the Virgin's head and the elongation of her hands.

Eagleston's study also made use of infrared and ultraviolet images of the painting -- also on display at the Cantor Center -- and of microscopic cross-sections of paint taken by conservator Tony Rockwell, who recently completed the painting's restoration at the FAMSF conservation studio.

The infrared images, shot with an appropriately tuned digital camera, were particularly revealing. Rockwell explained that infrared rays tend to penetrate through the layers of paint but not through carbon-based materials such as pencil, laying bare the drawings the artist sketched on a gesso base before painting. The drawings hidden under the Virgin definitely look like Sellaio's, Eagleston said, especially in his use of hatch marks to plan out the areas of shadows.

The Virgin is in relatively good condition for a painting of its age, Rockwell said. While he did fix some damage and fill in some abrasions, his most challenging task was cleaning and consolidating the paint. He removed layers of grime, darkened varnish and some retouched areas from previous restorations. He then applied a new varnish that is more permanent yet remains soluble. "We want our restoration to be reversible," he said, "so that in future generations it can be undone as needed."

Robert Mindelzun, a professor of radiology at the Stanford Medical Center who first met Roberts-Manganelli when she needed an X-ray of an Egyptian mummy, checked the panel's health with ordinary X-rays and with a CT scan. With Stanford's state-of-the-art CT scan machine, "we can now scan with a detail width of six-tenths of a millimeter," Mindelzun said. He used the data to produce 3-D animations that show the inner structure of the wood, including holes caused by tunneling worms.

Despite the bugs' efforts, the panel has held up well to the tests of time, Rockwell said. It was made with four poplar boards held together by an ancient sort of superglue: a durable adhesive of hard cheese -- probably something similar to Parmesan -- and lime, he said. The structure was later strengthened by adding a cradle to its back.

Later this year at SSRL, physicist Apurva Mehta will analyze microscopic samples of paint from the Virgin. SSRL's X-ray source, Mehta explained, produces intense, precise beams that can be finely tuned to spot trace elements in the smallest samples. These trace elements can help determine the geographic origin of the minerals the painter ground up to make his temperas.

Both Mehta and Roberts-Manganelli see the project as just the beginning of a campuswide collaboration on art conservation, which could include conservators, art historians, physicists, geologists and materials scientists. "The whole point of doing this is to create a community that has a common language," Mehta said.

Davide Castelvecchi is a science writing intern at the Stanford Linear Accelerator Center.