Modern technology at the service of cultural heritage. Researchers from various disciplines are working together to preserve and study treasures form the past.
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.”
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.
25 years of cooperation
25 years of cooperation
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.
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.
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.
Preserving Pompeii for posterity
Modern buildings are designed to have a lifespan of around 50 years. But in historical terms, that is a mere blink of an eye. We would like archeological sites like Pompeii, for example, to stand the test of time immemorial. Preserving sites such as this with the most basic materials represents a huge scientific challenge. As part of the “Pompeii Sustainable Preservation Project”, researchers from Technische Universität München (TUM), Fraunhofer-Gesellschaft and ICCROM will spend the next ten years investigating long-term solutions to prevent the UNESCO world heritage site of Pompeii from falling further into ruin.
As one of the largest self-contained sites surviving from antiquity, Pompeii is a treasure trove. Each new excavation yields new knowledge, and is greeted with huge interest by the public and research community. All too often however, a lot less interest has been shown in the sustainable preservation of this unique site.
Many of the finds, most notably Pompeii’s frescos, have been moved to museums, to protect them from the wind and weathering. But because of inadequate conservation measures, the exposed walls of the city with their lavish decorations are now visibly disintegrating.
Pompeii as a center of world-class research
The researchers participating in the Pompeii Sustainable Preservation Project intend to concentrate on one of Pompeii’s apartment buildings, known as an insula. From 2014, they will embark on an ambitious conservation program, taking in everything from elaborate murals to the smallest wall. “The first step will be drainage, followed by new types of protective structures. But that is just the start,” explains Professor Erwin Emmerling of TUM’s Chair of Restoration.
An important new approach is preventive restoration. “To date, this has not been undertaken on an adequate scale. We want to find out more about ongoing restoration,” continues Emmerling. The researchers will only use simple, traditional materials. In any case, large equipment like cranes would be of no use in the narrow streets of Pompeii. They will also have to make do without concrete because it was not used in those days. Instead, the restoration team will use lime and other traditional building materials.
Modern technology for ancient monuments
But the researchers will not be foregoing all high-tech aids. They will use nanotechnology to make the lime more fluid, thus stabilizing the frescos through backfilling. The experts intend to conserve the topmost layer of the paintings using lime and silicon compounds.
Researchers from various disciplines will be working alongside restoration experts and archeologists in the Pompeii Sustainable Preservation Project. The ancient city will be accurately surveyed both on the ground and through aerial photographs. Seismic measurements will provide information on how the monument will be impacted by future seismic activity, which will help to ensure that the conserved structures will later withstand these tremors. Construction and structural engineers will be supporting activities in this area.
Last but not least, suitable sites within Pompeii are to be re-landscaped, and the project as a whole will be a training site for conservationists from around the world.
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).
To read the full posts about these two research projects: “Conservators preserve the paint layers of the Terracotta Army“; “Preserving Pompeii for posterity Army“.