As we can see in the damaged areas with a lower layer of a coarser arriccio and an upper layer consisting of a finer intonaco, the mural was painted on at least two layers of plaster. The separation between the two is not always clear. The XRD analysis of the crushed plaster has revealed a high quartz and low calcite content, while feldspars, illite/muscovite, pyrite, and dolomite are also present. The latter can be both in the binder and the aggregate. The plaster is thus dominated by the aggregate, with modest binder content, which is why it is rather brittle. The samples’ cross-sections also show densely distributed angular and varicoloured grains in a small amount of lime (Figs. 7–8). There are many translucent angular grains, probably quartz, while the angular shape of the grains also suggests the use of crushed sand. In all three samples, another layer can be found between the plaster and the colour layer. It has been impossible to determine whether this is limewash or a very thin plaster made of lime and crushed marble or calcite/dolomite. In one of the samples, the layer in question is more like an extremely thin plaster (Fig. 7), which is unusual and has only been detected in the mural on the chancel side of the triumphal arch wall in the succursal church of the Virgin Mary on Kamen in Vuzenica. The specificity of this element could suggest that the same workshop worked at both locations, but unfortunately, we do not have enough samples to confirm this assumption. Due to the fragmentary preservation of the mural, which is largely covered by a more recent painting, we do not know whether the plaster was applied according to the system of giornate.