Ancient color feast: the application of digital microscope in classical sculpture

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Ancient color feast:

The application of digital microscope in classical sculpture

Jan Stubbe Ostergaard ¹ Kerstin Pingel ²

¹ Ny Carlsberg Glyptotek, Copenhagen, Denmark ² Leica Microsystems

December 15, 2009

In the impression of everyone, the ancient marble sculptures are all white. But is this really true? Scientists at the Copenhagen Painted Network (CPN) showcased Greek and Roman sculptures with luxurious decorations and gorgeous colors. With surgical microscopes and digital microscopes, the Heritage Protection Commissioner can detect subtle traces of paint pigments and restore the color feast of ancient times.

For example, the great German scholar Johann Joachim Winckelmann of the 18th century followed the traditional concept of “pure white is the true beauty”. Today, we still adhere to this philosophy in aesthetics. But as we all know, since the 19th century, ancient sculptures have begun to use painting techniques, that is, "multi-color" techniques. Specifically, mineral materials such as azurite and malachite are finely ground, and then mixed with an adhesive such as egg or casein. The painted sculpture enhances the three-dimensional effect of the sculpture and conveys important clues for the audience to understand the artwork. For example, when tourists visit the castles of the ancient times, they can only recognize the statues of the Persian knights, because these knights are decorated with diamond patterns typical of the Eastern countries.

Interdisciplinary network for basic research

“We all know that color is an important part of all ancient Greek and Roman sculptures,” said Jan Stubbe Østergaard, head of research at the Museum of Ancient Art in the New Carlsberg Art Museum in Copenhagen. “But it’s hard to really understand this phenomenon.” In many of the ancient sculptures in the global museums, we have had relatively few in-depth studies of painted sculptures. The Copenhagen Paint Network is an interdisciplinary research team that includes the New Carlsberg Art Museum, the Royal Danish Academy of Art, the University of Copenhagen's Geological Museum, and the Department of Chemistry at the Technical University of Denmark. The research team aims to sculpture the sculptures of the New Carlsberg Art Museum. Study and record the traces of color. The research task is very urgent, because these color traces are gradually disappearing.

Microscope image becomes the only clue

Since some of the pigment residue on the sculpture is very rare, making it impossible to extract the sample, the microscope became the most important tool for the Heritage Protection Commissioner Maria Louise Sargent. “What I observed through the microscope is the only clue to color,” says the Heritage Protection Commissioner. “So, I will systematically observe the sculpture and make sure that I don’t miss any clues about the paint. This is very important.” Maria Louise Sargent used a surgical microscope and a digital microscope.

“The digital microscope has great flexibility,” said the Heritage Protection Commissioner. “These sculptures are up to two meters high, and our scanning work must be accurate to every centimeter. In addition, the magnification of the digital microscope can reach 160x. As a result, the color pigment and the original pigment residue are no longer just traces, now We can more easily detect and analyze these clues. Through digital microscopes, we can record videos and images, and present them on the monitor during the discussion. After the area, the microscope will save the digital image and form a record.

Cooperation with the British Museum

In the process of searching for traces using a surgical microscope, Sargent found extremely small amounts of blue pigment on the Greek limestone figure in 580 BC. For the identification of pigments, Danes hopes to cooperate with the British Museum in the future. The “great crocodile” of the European museum community has started the painting project with the CPN model and listed CPN as an external research partner to carry out research work. “Our colleagues at the British Museum have developed a non-invasive method of using UV photography to detect Egyptian blue. We hope to get more information through this technology,” Østergaard said optimistically.

Showing traces of history for two thousand years

Currently, Maria Louise Sargent is working on the beauty of Palmyra, a limestone sculpture dating back to 1973-210 BC in Palmyra, Syria, with red jewels and a glass ball in the middle. . “These art treasures have been around for more than two thousand years, and they are full of stories and legends,” Sargent said. "In other words, I can see a lot of traces, including traces of environmental pollution or erosives. The harder job is to accurately identify these traces." After all, these ancient painters used materials such as ochre as a colorant. The color is the color of the earth. So which part is the pigment, and which part is only taken from the local soil? Just as charcoal has been used as a black pigment by the ancients, and carbon ions are also an indication of modern air pollution.

Controversial view: Is the skin colored?

By observing the statues of Greek figures with the naked eye, you can see the traces of various colors on the eyelashes and lips. Østergaard is looking forward to a truly important discovery: “The detection of this object may help to answer the question of whether the skin of an ancient figure statue has been painted. So far, we have only one evidence from the classical period and the Greek period. Prove that the character's body is painted with skin color pigments."

Objective physical analysis reveals the origin of pigments

In the case of sufficient pigments, we will select small pigment samples and cross-sectional inspection with a material inspection microscope to determine the layered structure and, if possible, to identify the pigments, some of which need to rely on the CPN Cooperative Research Institute. Physical analysis results. Therefore, Minik Rosing of the Geological Museum can specify the origin of the pigment by analyzing the isotope trace elements: “A sculpture of red lead powder is produced in Spain and exported to Rome,” Østergaard said. “This also provides clues for us to study ancient trade routes.”

Painting research has a long way to go

Although CPN has achieved some notable research results, the research on painting is still in its infancy. “Even if we can identify the colors of ancient sculptures, we still don’t know their true face,” Østergaard pointed out the current work problems. “So, we need to understand more details about the craftsmanship and the aesthetics of ancient painted art.”

At the 2012 major exhibition in Copenhagen, the new Carlsberg Art Museum will be showcasing the latest discoveries of many sculptures using microscopes.

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