LASER CLEANING OF EPITAPHS IN SAINT ELISABETH’S CHURCH, WROCŁAW, 2018
The project consisted in removal of dirt and deposits which typically occur in a polluted urban atmosphere from four epitaphs made of various kinds of stone, namely the epitaph of MAŁGORZATA FRANZ (sandstone, marble), the epitaph of HEINRICH WRBSKY VON WRBY (marble), the epitaph of ANNA HEIDENREICH née LIBITZ (limestone), and the epitaph of TOBIASZ PLAKWITZ and his wife (marble).
As the deposits formed a thick and well-compacted crust which firmly adhered to the substrate, a decision was made to apply complementary methods for preliminary treatment in order to ensure integrity of the underlying original surfaces and to:
- avoid removal of natural protective patina,
- avoid any loss of original sculpted details or traces of original stone treatment,
- mitigate the risk of substrate discoloration.
The main treatment consisted of laser cleaning of the stone surfaces with a NdYAG Q-switched laser system with 1064 and 532 nm wavelengths and energy density adjusted according to the kind of stone treated and its condition.