# Degradation Products Assessment of the Wooden Painted Surfaces from a XVIIth Heritage Monastery
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c} \hline
**Sampling Site** & **Sampling Point** & **Sample Name, Description and Analysis** \\ \hline St. Nichifor and St. Dimitrie Icon 1 (L*= 48.12; a* = 5.15; b* = 27.67) & Green decoration \\  & & FTIR, SEM-EDS, OM, GC-MS, colorimetry \\  & & \\ \end{tabular}
\end{table} 
Table 1: The description of the samples collected from Techirghiol church (Church Naos–eastern part). Figure 3: The optical microscopy of the efflorescence generated by blue pigments. In the case of optical microscopy, whitish points and small fragments of metallic soap or varnish are visible in all the investigated fragments, as a sign of the metallic soaps generation or subsequent conservation procedures, Figure 5. A fractally aggregated distribution of the metallic soaps is visible and these images are a conclusive image of the damage propagation. It is known that the zinc oxide is a pigment that readily reacts with fatty acids in oil-based paints to form zinc carboxylates. Zinc stearate and zinc palmitate aggregates are associated with deterioration in late 19 th and 20 th century paintings, following the fractal aggregation theories [40]. In this context, for a better visualization, SEM images are used to identify the material structure aspect, degradation processes, or conservation additions. Effects such as porous  
Figure 4: Stereomicroscopy of blue pigment with white deposit (**A,B**) images and SEM images of blue pigment (**C**) and of the white deposit (**D**). Figure 5: The optical microscopy of the metallic soap generated by the pigments. film, cracks and an irregular surface, holes in and under the surface, and overlapping layers of paint could be observed. Further, the additional white area is seen in Figure 6, attributed to the plaster used to cover the holes, or missing part of this icon. SEM images show that the soap exhibits several small (semi-)crystalline domains, each with a coordinated layered structure of 50-100 nm in size, without a specific orientation. The newly formed structures are organized in successive layers that formed a 3D flower-like structure generated by the initial precipitation of the zinc soaps. The distribution of these domains is quite homogeneous, thus confirming the hypothesis that the nucleation processes take place in the binding environment and not at the level of the pigment particles [41]. This finding suggests that zinc soaps can be present as amorphous zinc carboxylates, bound to the network of oxidized, cross-linked oil, as well as crystalline zinc soaps, generated by paint degradation [42]. The WDXRF analysis, of the pigments Table 2, reveals that the common contributing elements detected in the red layer were Fe, Ca, Al, and Si (EDS analysis display similar semi-quantitative results). Additionally, Ba is present, but not P, which could mean that black bone has not been used. It is suggestive of a Fe-based pigment such as an ochre possibly mixed with calcium carbonate or sulphate (sulphur has a high concentration), possibly from the gypsum identified on the restored part of the painting, Figure 7.  
The EDS analysis reveals the presence of sulfur (S), which can be bound to both calcium (Ca) and barium (Ba). Barium is generally present in the paint layers as barium sulfate (BaSO4), a white thinner commonly used for pigments, or as lithopone (BaSO4 and ZnS). Indeed, synthetic barium sulfate was developed in the early 19 th century. Lithopone is a white pigment produced since 1874 and widely used in soil layers or as filler [43]. The calcium could be related to the presence of calcium sulfate (gypsum, CaSO4), which was commonly used as a preparation layer from early medieval times to modern times [44]. The analysis also highlighted the presence of zinc in the primer layer, confirming the use of zinc oxide (Zinc White). Gypsum (CaSO4 2H2O) was rarely found and used alone or in combination with ZnO. Figure 6: SEM images of green, red and blue colored samples (from left to right).