The wall paintings excavated in the 1960s to 1980s had been consolidated in a makeshift way and some had been extensively restored. Now they exhibit many different patterns of damage. These include gaps and cracks that to various degrees cross through all layers of the plasterwork, especially salt efflorescences. The salts originate from the restoration materials among other things that were used during the temporary securing. Lime and partially gypsum rich mineral crusts are located on the material surfaces and they developed on surfaces during the long floor storage; this is mainly an aesthetic issue. On some places there is also microbial growth.
Approach and method
Before the actual restoration measures begin, a comprehensive photographic documentation of the actual condition takes place and all surfaces are freed from dust and dirt with a dry and/or wet cleaning. The safeguarding of severely endangered plaster areas is part of the first steps in the process. Here the hollow spaces are filled with a lime-based injection mortar in order to establish a connection with the underlying layers. Open edges are closed with batterings of lime mortar. Structurally damaged areas of the coarse or fine plaster are consolidated with lime-based firming agents. The removal of mineral crusts is carried out depending on the type of crust mechanically with the scalpel or chemically by ion exchange resins or ammonium carbonate dressing. If a desalination is necessary this is carried out with dressings and deionized water. The cement mortar added during earlier restorations and emergency safeguarding was gradually removed and replaced by more appropriate consolidation agents.
All measures are carried out under strict observation of the material. It is very important that all visible furnishing phases and also all destruction traces remain legible.
In order to document and subsequently be able to evaluate and interpret the climate conditions within the protective construction climate measurements have been taken since 2014 using data loggers. Here the temperature and relative humidity is measured throughout the year. The generated data will provide a fundamental overview and monitor the climatic situation and will provide insight into possible problematic areas or fluctuations. When necessary, on this basis measures can be taken in line with preventive conservation. The creation of appropriate conservation conditions is one of the mainstays in the development of a concept for the long-term preservation of the wall paintings in addition to their practical conservation and restoration.