Zastosowanie najnowszych technik nieniszczących w badaniach tynków zabytkowych na przykładzie dekoracji sgraffitowej w Bożnowie

Skuteczność konsolidacji rozwarstwionych i osłabionych strukturalnie tynków zabytkowych wymaga zarówno doboru odpowiednich środków konserwatorskich jak i znajomości zakresu występującej destrukcji. W czasie prac konserwatorskich przy dekoracji sgraffitowej w Bożnowie (Polska), w celu określenia zakresu występujących zniszczeń tynków, po raz pierwszy wykorzystano równocześnie technikę termowizyjną i radarową. Badania nieniszczące zostały uzupełnione analizami pobranych próbek metodami petrograficznymi, mikrochemicznymi oraz spektroskopowymi. Badania termowizyjne i radarowe powtórzono po zakończeniu prac konserwatorskich, co pozwoliło na ocenę skuteczności wykonanych zabiegów.

The efficiency of consolidation of exfoliated and weakened historical plasters not only requires the choice of appropriate materials and careful examination of the range of destruction. In order to evaluate the deterioration of plasters of the sgraffito decoration in Bożnów (Poland) both thermovision and ground penetrating radar (GPR) techniques were applied jointly for the first time ever. Nondestructive testing was preceded by analysis of samples with petrographic, micro-chemical and spectroscopic methods. Thermovision and radar examination was repeated after the completion of restoration works, which allowed evaluating the efficiency of treatment performed. Sgraffito ornamentation on the northern wall of the western tower of the church in Bożnów was completed by Christoph Rutsch and his two assistants in 1609. The two-color technique was applied. Ornaments were scratched in moist, white lime paint applied on fresh lime plaster colored grey with charcoal. A collective character of the work is visible due to diversified workout of figures, ornaments and inscriptions. In the 19th century the sgraffito must have already been deteriorated and looked unattractive so it was punched with a hammer and covered with a layer of plaster. In 1931 the decoration was discovered by German scholars but it was plastered up again due to a poor state of preservation. It was uncovered again in 1972 and subjected to restoration treatment. For over 30 years the object was exposed to rainwater from the tower roof, which washed out lime paint and yield delamination and plaster losses. Except rainwater also capillary water was responsible for the deterioration of the ornament, as well as changing temperature and humidity conditions characteristic of outdoor exposure.