Laser cleaning applied in the restoration of a medieval wooden panel chamber at Pirna

This contribution presents, as a first result of thorough investigations concerning the effect of laser irradiation on wood, the laser cleaning applied in restoration and conservation of 600 years old wooden panels in an historically important building at Pirna. They were uncovered during archaeological examinations in 1994. In one room of that building the work of restoration revealed fully preserved wooden panels on walls and ceiling. Most panels on the walls are severely damaged and covered with multiple paint layers. Aim of the work is to remove the multiple paint layer (lime, casein paint) from the severely damaged wooden panels. Conventional cleaning tests showed that none of the methods known to restorers met the requirements. Therefore laser cleaning was tried. Investigations, like thermal measurements and SEM-images show that there is no damage due to laser cleaning. The ablation rate of laser cleaning depends on grade of decay and on thickness of paint layers. This presentati on shows that ablation with short pulsed Nd:YAG-laser could be a new method for restoration of damaged wood surfaces.