Restoration work on the figure of Vishnu.

Angkor Wat (Cambodia)

In south-east Asia, amidst the jungles of Cambodia, lie some of the most impressive cultural sites in the world. The temple complex Angkor, which has been in the UNESCO World Heritage List since 1992, captivates visitors with its majestic dimensions and wide variety of art forms.

From the 9th till the 14th century, Cambodia was the heart of high Khmer culture. The largest and most important temple in the area is Angkor Wat. Its surfaces are decorated with unique stone sculptures, including almost 1850 divinities (known locally as „apsaras“), bas-reliefs up to 100m long in the galleries and richly-decorated tympanums which look as though they have been carved from wood. These latter, however, are in a worrying condition; many have already fallen victim to the weather.

Restoration work at prasat kravan temple.
Restoration work at prasat kravan temple. © Leisen/TH Köln

Since 1995 a team from Cologne University of Applied Sciences has been working to prevent further decay. The restoration and conservation measures are being carried out by lecturers and students from the Institute of Restoration and Conservation Science in cooperation with a team of Cambodian conservators. The project also receives support from external scientists in the fields of geology, geomicrobiology and chemistry.

Every natural stone has its own characteristic properties; each one reacts differently to the effects of the weather. Since 1995, therefore, the sandstone blocks used to build Angkor and the damage already caused have been the subject of detailed investigation so that decisions can be taken on the most suitable conservation methods. Every situation, every temple, is considered individually, and all steps in the process must be documented in detail.

A thorough survey revealed that about 300 apsaras and a large number of reliefs on the pediments of Angkor Wat were so badly damaged that large pieces of stone could fall off at any time. Since 1998 the weather-beaten reliefs have been undergoing painstaking conservation. However, it will not be possible to prevent further damage completely. Continual monitoring and maintenance will be needed.

Documentation and conservation of life-size elephants.
Documentation and conservation of life-size elephants. © Leisen/TH Köln

The German Apsara Conservation Project (GACP) began in 2003 with an examination of further temples in Angkor Park, including the early brick temples with their amazing stucco decorations. On the basis of the findings, conservation measures were successfully carried out. In 2006 work extended also to Koh Ker temple, north-east of Angkor. In 2008 work began on the derelict remains of Preah Khan Kampong Svay.

If the work is to be successful, the workers must undergo constant training. As part of the project, the GACP trained the Cambodian conservators. Students from Cologne University of Applied Sciences and other universities can help with project work during their practical semester or help with dissertations. Playing a part in a major scientific research project on a UNESCO World Heritage site is a unique opportunity for the students.

Project: Prof. Dr. Hans Leisen, Project Director, Cologne University of Applied Sciences

Promoted by: Cultural Preservation Programme of The Federal Foreign Office

Source: Worlds of Culture, Ed. Federal Foreign Office

Borobudur - A Detail of a Relief

Borobudur – A World Cultural Heritage Site at Risk (Central Java, Indonesia)

On 26 October 2010, Mount Merapi, one of the most dangerous volcanoes in the world, became active again. It erupted on 5 November, causing extensive damage. Borobudur, which has been a UNESCO World Cultural Heritage site since 1991, was completely covered by a layer of volcanic ash. Cleaning work was undertaken immediately, and also received funding from Germany. However, the question subsequently arose of how harmful the volcanic ash was for the precious reliefs. In order to answer this and other questions, the Cultural Preservation Programme of the Federal Foreign Office has been funding a UNESCO stone conservation research project since 2011, which is being carried out in cooperation with the Borobudur Conservation Office (BCO) and the Indonesian Ministry of Education and Culture.

Borobudur Temple was built under the Sailendra dynasty during the eighth and ninth centuries. Its design and stone reliefs make it one of the most impressive World Heritage sites. Six square terraces with 1460 reliefs depicting scenes from Buddhist mythology, niches with countless sculptures of the seated Buddha, a further 72 statues of the Buddha in bell-shaped stupas on circular terraces, and the main temple at the top of the monument were built in the fertile Kedu Plain, the Garden of Java. The foundation, a natural hill formed by aggradation, already proved to be unstable at the beginning of construction work. The volcanic building stones andesite and basalt were not extracted from quarries, but rather from the rivers.

The first large-scale restoration project was carried out between 1907 and 1911 and coordinated by Theodore van Erp. The walls were at risk of collapsing, and water was shooting out of the relief walls. During the restoration, the walls were stabilised and the drainage system was improved. The next major restoration phase took place between 1973 and 1983. This UNESCO project was run by Caesar Voute from the Netherlands. All of the relief walls and galleries were dismantled and rebuilt (anastylosis), while stabilising concrete platforms and an internal drainage system were integrated into the monument.

The complex internal drainage system created new problems. The magnificent reliefs remain exposed to destructive moisture penetration and frequent leaks. Another threat to the reliefs is posed by ongoing crust formation and flaking on the stones, as well as by salts that damage the structure. The great range of features in the building stones mean that the degree of damage varies among the reliefs.

Apart from providing scientific documentation and analysis of the weathering process, experts are developing a wide range of methods and materials to conserve the reliefs. As part of the cooperation, the BCO’s researchers and restorers are receiving further training in modern analysis and conservation techniques.

Project: Prof. Hans Leisen and Dr. Esther von Plehwe-Leisen, Project managers, Cologne University of Applied Sciences

Promoted byCultural Preservation Programme of The Federal Foreign Office

Source: Worlds of Culture, Ed. Federal Foreign Office