The German Apsara Conservation Project
The German Apsara Conservation Project has been working on the conservation of the decaying sandstone reliefs at Angkor Wat since 1997 and has developed special techniques to face the unique and delicate problems posed by this site.
In order to organise a coherent and applicable approach to the conservation of this vast temple a risk map was prepared in order to prioritise the various problems and to enable the technicians to confront each damaged part of the temple in a logical and systematic way. The initial work was carried out on the apsara reliefs which were the most exposed and decayed carved elements of the temple, however as the work proceeded, and the level of risk of these parts was gradually reduced, so other parts of the site earned their place at the top of the priority list. By 2000 it was the turn of the reliefs in the galleries which though protected from the weather were suffering from serious decay from a variety of other factors, not least poorly executed conservation procedures and errors in the choice of conservation materials.
It was at this point that FOKCI approached the GACP with an offer of funding and it was decided that the most appropriate place for the focus of a FOKCI funded conservation operation would be the carved reliefs in the South West Pavilion of the third enclosure. These delicate and beautifully carved reliefs depicting various scenes from the Ramayana had been the object of a conservation operation in the 1980s which had filled the cracks with Portland cement and then sealed the surface of the stone with a dense acrylic resin in an attempt to protect the reliefs from the infiltration of water.
While it is certain that no water penetrated the surface as a result of this intervention, unfortunately the conservators had not foreseen the devastating effects of the penetration of moisture from other sources, and now that the surface was sealed the moisture continued to pass through the stone, dissolving the various soluble salts, in particular those new and dangerous ones added by the application of the Portland Cement, but was unable to pass through the sealed surface of the stone. The result of this was that the stone began to peel with devastating consequences for the reliefs on the surface. It was clear that it was of the utmost importance to remove this resin and to desalinate the stone as soon as possible if the reliefs were to be saved from inevitable loss.
The GACP team began testing methods and materials and was able to define a method that removed the resin without damaging the stone. The Portland Cement was also removed and desalination poultices were applied to reduce the salt load. This method was developed in collaboration with the Cambodian conservators of the GACP conservation team and soon they were able to carry out this work with reduced supervision from the international experts. The methods involved the application of a poultice composed of paper pulp and absorbent clay (Atapulgite) in which was suspended a mixture of butanon and acetone. This mixture was able to dissolve the resin and the process of evaporation then drew it in to the poultice allowing the conservators to remove it with relative ease. The stone was then cleaned with poultices mixed with deionised water which drew out the damaging salts. Finally the cracks and joints were filled with a special mortar bound with Ethyl Silicate; a system which had already been tried and tested by the team in earlier operations on the apsara reliefs.
The operations on the South West Pavilion have now been concluded successfully and not only have the reliefs been given a new lease of life but their legibility has also been significantly enhanced.
Now that work on the South West Pavilion has been concluded operations have moved to the North West Pavilion where the same problems are faced by the reliefs. This work is still in progress.