EN
Prior to conservation completed in 1994, the bas relief material was subjected to specialist examination in order to determine its mineral composition, and torecreate upon this base the original composition. Samples taken from the original bas relief, dating from the end o f the seventeenth century, and repairs conducted in the inter-war and postwar period, were examined. Research was carried out by means o f the following methods: X-ray and thermal analysis, macroscopic and microscopic observation with a scanning electron microscope, and auxiliary chemical assay. The obtained results made it possible to ascertain that the bas relief was made of plaster mortar with an addition o f lime. In the initial composition o f the mortar, the ratio o f the dry binder to the mass of the filler totalled 1:2,4. The binder was semihydrate calcium sulfate and lime. The contents o f the former was much larger than that of the lime. The filler was high-silica sand in which the dominating size o f grains oscillated from 0,1 to 0,4 mm. An almost identical composition and structure belonged to material originating from inter-war repairs. A markedly different composition and structure were found in samples which came from postwar conservation carried out with lime mortar, with a distinctly smaller part played by the binder; consequently, the samples differed not only as regards the type but also the amount of binder in comparison to original seventeenth-century mortar.