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German government project for preservation of cultural heritage in China

Conservators preserve the paint layers of the Terracotta Army

Conservators preserve the paint layers of the Terracotta Army
Conservators preserve the paint layers of the Terracotta Army. (Photo: Blänsdorf/Lehrstuhl für Restaurierung, Kunsttechnologie und Konservierungswissenschaft)

Research news

They wore vibrantly colored garments with complicated patterns and colorful ribbons, one of them even had a face green with makeup. Every figure of the famous Terracotta Army is unique and deceptively realistic in its facial expression, hair style, clothes and stature. An incredibly detailed and hitherto unparalleled work of art. Conservators from the Technische Universität München (TUM) have spent years of intricate work to decipher and reconstruct the paint layers of the warriors and to find ways of preserving them.

Generals, archers, infantrymen, officers and charioteers: They all stand or kneel life-sized in the tomb complex of the first emperor of China, Qin Shi Huang. Experts estimate the number of figures in the famous Terracotta Army at some 7300. It was discovered in 1974 and is now a UNESCO World Heritage site. The full extent of the first emperor’s tomb site, which was built in the third century B.C., is unknown. To date, some 200 supplemental pits have been discovered strewn across a 50 square kilometer area surrounding the massive burial mound. The warriors are collected in three of these pits.

Catharina Blänsdorf from the Chair of Restoration, Art Technology and Conservation Science at TUM has spent over ten years analyzing and conserving the paint layers. The research work was part of a 25 years long cooperation with the Shaanxi province in China.

Elaborate detective work

The brownish gray character of the figures in the Terracotta museum situated at the original site is deceptive. The impressive warriors were once vividly colored, accompanied by imitations of horses and chariots and were even equipped with real weapons. However, when the figures are removed from the damp earth, the lacquered undercoat flakes off, stripping the warriors of their color.

Often, Blänsdorf had only tiniest paint fragments to guide her in reconstructing the original color finish. "It was definitely not a case of painting by numbers," emphasizes the conservator. The artists looked to nature as a model. In certain areas of the body, e.g. the shoulders, the patterns of the painted clothing appear contorted – just as they would be in real life.

Cryptic patterns

The clothing consisted of garments, undergarments, trousers and shinbone protectors. Each of these elements was colored differently and on special figures endowed with patterns. Some of the elaborate ornaments still pose a mystery to scientists. They can be roughly categorized into geometric forms like diamonds, stars and flowers, and zoomorphic patterns like birds, dragons and phoenixes.

The army had no uniforms. Ranks were distinguished by headdress and armor. Generals, for example, wore caps ornamented with pheasant feathers. Their armors were distinguished by intricately corded plates, patterned trimmings and silk fabric on their chests and backs. The apron-like armor of the chariot officers covered only their stomachs and was fastened by cross-straps on the back. These were divided into two strips, one of which lined the armor and the other the neckline. They wore caps with a tapered strip on the head.

Fascinating attention to detail

Every one of the figures is unique. Some generals have a well-fed tummy, but there are also stout infantry men. The artists rendered the facial details with a realism that even allows the different ages to be discerned. One of the archers is set apart with a green made-up face.

Catharina Blänsdorf was intrigued time and again by the attention to detail in the artistic depiction. Using a paintbrush, the artists produced a structural plasticity that rises from the background. They used this technique to emulate feathers, for example. "Eyebrows and mustaches are also realistically rendered in this manner," she says.

Polychromy of 55 figures reconstructed

Blue, green, red, violet, pink and white are the colors primarily used in the figures. Black and ocher are less frequent. The color base is made using inorganic pigments: malachite, azurite, vermilion, red and yellow ferrous oxide, white lead and bone black. The colors also include Han purple. This was produced in Chinese antiquity using a very elaborate technical process. Han purple was not rediscovered until 1983. Although the chemical structure has been established, the exact manufacturing process used remains unknown to this day.

In years of detective work, Blänsdorf has successfully reconstructed the original coloring of 55 figures. In addition to countless drawings and virtual reconstructions, three-dimensional models of the figures were made. A kneeling archer and a general made of plaster and  painted in the original colors are housed in the Münchner Museum für Abgüsse Klassischer Bildwerke. Blänsdorf has also completed the original color finish for a group of 18 kneeling archers. However, these figures were reproduced at a smaller scale (approx. 1:5). They are made of terracotta and are approx. 23 centimeters tall.

Blänsdorf discussed the results of her research in her dissertation at Staatliche Akademie der Bildenden Künste Stuttgart.

Countering evaporation

New figures of the Terracotta Army are still being discovered and excavated. However, today the paint layers can be preserved more effectively. The problem: The figures were originally coated with an East Asian lacquer, so-called qi lacquer. The artists then placed layers of paint on top of the lacquer. Egg was used as the binding agent. When the figures are removed from the damp earth, the moisture in the lacquer evaporates. The lacquer shrinks and the paint flakes off.

To prevent this, polyethylene glycol (PEG) can be sprayed onto the figures. The PEG replaces most of the moisture in the lacquer. The disadvantage of this approach is that the figures become darker than they were originally. With this treatment, cracks can also appear in the lacquer if the moisture evaporates faster than the solution can be applied. Finding a better method for conserving the colored finish and also the figures already on display are challenges that lie ahead for the Chinese monument conservers.

25 years of cooperation

The Terracotta Army is an example of the multitude of archaeological treasures that remain buried in the Middle Kingdom. "For many years now in the People’s Republic of China, hundreds of archaeological excavations are done every day," explains Prof. Erwin Emmerling from the Chair of Restoration, Art Technology and Conservation Science. "The pressure for change caused by rapidly growing cities and large infrastructure projects is so immense that the authority for the protection of monuments has great effort trying to salvage and store the countless discoveries."

In 1988 the German Federal Ministry of Research and Technology (today the Federal Ministry for Education and Research – BMBF) and the Chinese Commission of Science and Technology entered a cooperation agreement. The BMBF research project for the conservation of cultural heritage is built on this agreement. The last follow-on project ended in 2014. A number of Chinese and German institutions are members of the cooperation. The goal is the scientific exchange, continued development and testing of conservation processes for cultural artifacts of the Shaanxi and, since 2006, Sichuan provinces.

The Chair of Restoration, Art Technology and Conservation Science at TUM was able to participate in numerous excavations and restorations. Further research projects included Buddhist temples (8th and 16th century) and secular wall paintings of more recent history (19th century).

An overview on the German-Chinese research project with its sub-projects an all research reports.

Catharina Blänsdorf
Chair of Restoration, Art Technology and Conservation Science
Tel. +49 89 21124 564