Preserving archaeological discoveries requires as much care as unearthing them. The army of terracotta soldiers uncovered at Xi'an, China, is a wonder to behold but shows the dangers of poor conservation arrangements. After several years of public display and exposure to air, the terracotta is drying out and the figures are crumbling. The curators cannot reverse the deterioration and many now regret the original excavations.
Leaving discoveries in situ now appears more and more attractive to archaeologists. But this approach brings its own problems. Isolated sites may not benefit from the specialised buildings and on-site expertise that museums have and each case is different.
"Working with EUREKA had two major advantages: we found that the set up times for projects which involve governments were shorter than usual and we are benefiting from the publicity for our work that EUREKA is able to provide."
Milan Kovac Arkitektkontor AB
Milan Kovac, a Slovene-Swedish architect, has spent most of his working life developing techniques and technology which can preserve ancient objects and monuments in near perfect condition at their site of discovery. He led the Swedish and Slovenien project partners in the EUROCARE ARCH IN-SITU project aimed at developing techniques to assess the needs of different sites and find customised solutions to the individual problems. The project brought together an array of experts including archaeologists, lighting engineers, materials scientists and microbiologists to tackle problems ranging from climate and weather through pollutants such as acid rain to careless tourists.
One of the outcomes has been a better understanding of how to design protection shields using multilayer glass to cover the site of the discoveries, in combination with careful ventilation and light filtering. The construction supporting the glass plays a key role in stabilizing the area and protecting it against vibrations.
Laminated glass plays an essential role as it can be partly load-bearing where support for the artefacts is necessary. The glass is usually thermoglazed and contains a membrane that, when connected to an electrical supply, gives out just enough heat to counteract the effects of condensation. Careful adjustments are made to ensure that no heat is reflected towards the artefact and air-cooling and ventilation keep stable the temperature and humidity within the preservation chamber.
This expertise has now been deployed at Crnomelj in Slovenia. Work on a new building there uncovered the remains of an Iron Age settlement, a Roman defence wall and tower and a medieval settlement with two city walls. Kovac's team has redesigned the original plans for the building so that construction has continued on the upper floors, leaving the ground floor and basement as a museum. The excavated flooring has been preserved by a glazed and sealed floor and the basement walls are also protected by extensive glazing. Artefacts found on the site are displayed where they were found during the excavation. The technique has also been used for the in-situ protection of Robba's fountain in Ljubljana.
"In the future, we hope to be able to set up a team of glass producers, heating and lighting companies and consultants, to advise and set up preservation projects all over the world. We want to help save the heritage of future generations," says Kovac.