## 3 Results and Discussion
### Wooden Material
These domains of IR contain the most relevant \"fingerprints\" bands for attesting the nature of lime wood support [39] as previously reported in [40; 41; 42] on one hand and for identifying the major decay products on the other. After carefully analyzing the wood spectra illustrated in Figure 7, it can be remarked that almost all \"fingerprints\" bands in the IR bands mentioned before are present in all three types of lime wood, e.g., fresh, dry, and sampled from iconostasis, but with different amplitudes depending on the degree of alteration; see Table 1 and the comments below. Figure 7: FTIR spectra of reference fresh, dry, and iconostasis wooden material. According to [43], between 3600 and 2800 cm\({}^{-1}\), there are valence vibrations assigned to the cellulose skeleton corresponding to (**i**). \(\
u\)O-H, which is slightly moved from 3337 cm\({}^{-1}\) intense in fresh wood to 3345 cm\({}^{-1}\) medium in dried wood and to 3338 cm\({}^{-1}\) weak in iconostasis wood (Figure 7); (**ii**). aliphatic chains \(\
u\)C-H at 2900 cm\({}^{-1}\) medium with a shoulder at 2800 cm\({}^{-1}\) in fresh wood and 2850 cm\({}^{-1}\) weak and large in dried wood, while the 2800 cm\({}^{-1}\) line becomes very weak and flattened in the iconostasis (Figure 7). These changes could be attributed to water loss in the case of dried wood or through the action of the microclimate, where the poly-condensation reactions take place between the OH groups grafted on the cellulosic chains. Consequently, the orderly arrangement of the polymer chains is destroyed, so the smaller the number of OH groups, the lower the amplitude of corresponding infrared bands, which significantly diminishes in the case of iconostasis wood (Figure 7). All of these changes that denote significant damage to the cellulose chains of the decayed iconostasis wood are also evidenced in Table 1.  
Moreover, between 1800 and 600 cm\({}^{-1}\), we have observed a similar behavior of more specific lines attributed to (**i**). \(\
u\)C=O in unconjugated hemicelluloses at 1735 cm\({}^{-1}\); (**ii**). the \(\delta\)H-O-H line of absorbed water molecules on the cellulose chains at 1624 cm\({}^{-1}\) is completely absent in the case of iconostasis wood, suggesting a drastic dehydration compared with the dried wood; (**iii**). \(\
u\)C=O embedded in the aromatic skeleton of the lignin line at 1593 cm\({}^{-1}\) is significantly attenuated in the case of iconostasis wood, most probably related to a decrease in the lignin amount; (**iv**). the valence vibration assigned to \(\omega\)-CH- cellulose at 1319 cm\({}^{-1}\) shows the same tendency of a major decrease in the cellulose and hemicelluloses amount; (**v**). \(\
u\)C=O lignin belongs to acetyl in the carboxylic moiety of xylan at 1234 cm\({}^{-1}\), testifying also the degradation of the lignin skeleton (Table 1). The significant loss of cellulose and hemicellulose and the deterioration of the lignin matrix, as well as the presence of black stains, could be related to bacteria and mold attacks, which feed themselves by the consumption of cellulose and lignin, respectively [37]. For this reason, it is most plausible that the released metabolites are responsible for the gray and black stains, which can be remarked on in the wood samples illustrated in Figures 3a and 5c. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline  
In this regard, the FTIR spectra of the iconostasis wood (Figure 7) did not show the presence of infrared bands corresponding to \(\
u\)C=O carbonyl compounds, as well as those of \(\
u\)C-OH and \(\
u\)COOH, all of them properly corresponding to carboxylic acids related to the oxidative aging decaying product reactions according to Equations (2) and (3). Complementary to FTIR, SEM furnished high-resolution images of wood fibers and their alteration, such as the loss of cell wall components or their decay (Figure 8), as well as traces of foreign material, most possibly fragments of gesso due to former restorations (Figure 8a,c).