# Degradation Products Assessment of the Wooden Painted Surfaces from a XVIIth Heritage Monastery
## 3 Results and Discussion
The presence of silica (Si), aluminum (Al), magnesium (Mg) and iron (Fe) suggests the use of green earth in the first layers of paint [45]. This could be partially responsible for the bluish-green color of the paint layer, along with the presence of chromium (Cr), which could be attributed to either green chromium oxide, vriidian (hydrated chromium (III) oxide) [46]. The presence of magnesium, silica, and calcium, may indicate calcium and magnesium silicates in all blue pasts. Iron oxide pigments were also used to produce the red shades [47]. Iron oxide paints are durable and resistant to light and weather. The intensity of their color depends on the amount of the present chromophore: hematite (red), hydrohematite (mummy or red-brown), goethite (yellow), etc. The brown and red-brown paints were found to contain impurities of baryta white. The black pigment is most likely bone black, with such a finding being indicated by the presence not only of carbon, but also of magnesium and calcium phosphates [48]. Depending on the ratio of the components involved, for blue colors the hues vary from blue-green to violet, which, when mixed with white pigments, emit hues ranging \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{3}{c}{**Sample**} \\ \cline{2-4}  & **Green** & **Red** & **Blue** \\ \hline
**C** & 43.43 \(\pm\) 0.21 & 25.25 \(\pm\) 0.13 & 38.26 \(\pm\) 0.19 \\ \hline
**O** & 42.17 \(\pm\) 0.73 & 49.21 \(\pm\) 0.25 & 39.15 \(\pm\) 0.56 \\ \hline
**Na** & & 0.34 \(\pm\) 0.01 & \\ \hline
**Mg** & 0.20 \(\pm\) 0.01 & 0.03 \(\pm\) 0.01 & 0.25 \(\pm\) 0.01 \\ \hline
**Al** & 0.56 \(\pm\) 0.01 & 0.13 \(\pm\) 0.01 & 0.64 \(\pm\) 0.01 \\ \hline
**Si** & 1.09 \(\pm\) 0.01 & 0.28 \(\pm\) 0.01 & 1.35 \(\pm\) 0.01 \\ \hline
**P** & 0.35 \(\pm\) 0.01 & & 0.74 \(\pm\) 0.01 \\ \hline
**S** & 1.09 \(\pm\) 0.01 & 11.31 \(\pm\) 0.04 & 1.60 \(\pm\) 0.01 \\ \hline
**Cl** & 0.19 \(\pm\) 0.01 & 0.19 \(\pm\) 0.01 & 0.14 \(\pm\) 0.01 \\ \hline
**K** & 0.14 \(\pm\) 0.01 & 0.18 \(\pm\) 0.01 & 0.15 \(\pm\) 0.01 \\ \hline
**Ca** & 6.84 \(\pm\) 0.03 & 11.10 \(\pm\) 0.05 & 5.17 \(\pm\) 0.03 \\ \hline
**Ti** & 0.32 \(\pm\) 0.02 & & 0.05 \(\pm\) 0.01 \\ \hline
**Cr** & 0.70 \(\pm\) 0.02 & & 0.15 \(\pm\) 0.01 \\ \hline
**Fe** & 1.68 \(\pm\) 0.03 & 0.17 \(\pm\) 0.01 & 4.83 \(\pm\) 0.04 \\ \hline
**Zn** & 0.73 \(\pm\) 0.05 & & 7.54 \(\pm\) 0.07 \\ \hline
**Ba** & & 1.92 \(\pm\) 0.05 & 0.44 \(\pm\) 0.02 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The elemental analysis (WDXRF) of the investigated pictural layers. Figure 7: The presence of gypsum on painting layer. from pale blue (paleo) to grey-blue [49]. In this context could be the L*a*b* value for each color collected and measured from the icons (Table 1). At temperatures above 250 \({}^{\circ}\)C (candlelight), the pigment may darken, sometimes acquiring a greenish tint. The aspects of FTIR spectra of the main components that could be identified for all the present pigments from both icons, are shown in Figure 8.  
The red layer displayed a pronounced broad band between 990 and 1290 cm\({}^{-1}\). Such spectral regions host features compatible with those of a sulfate (983, 1087, 1116, and 1182 cm\({}^{-1}\)), probably barite (BaSO\({}_{4}\)), to which the two uncertain peaks at 611 and 638 cm\({}^{-1}\) also appear to be assigned. Barite could be present as a natural impurity, since its identification as an artist's pigment occurred long after the making of this icon [50; 51; 52; 53]. Small amounts of anhydrite (CaSO\({}_{4}\)) and arcanite (K\({}_{2}\)SO\({}_{4}\)) were detected, and their presence can be attributed to interactions with environmental pollutants. The presence of hematite supports the EDS results, through Fe content. Additionally, calcite could be identified by the bands from 1440, 875, 712 cm\({}^{-1}\), because usually calcite is used as mix or as substrate for painting [54; 55].