## 3 Experimental Results
### Physical Properties of Subfossil Oak in Comparation with Aged Oak from Construction and Recent Oak
#### 3.1.2 Swelling and Shrinkage, Anisotropy and FSP
Figure 4: Box plots of total swelling (**a1**–**a4**) and total shrinkage coefficients (**b1**–**b4**), illustrating the variation in these values among the different assortments of oak wood and dispersion of data in each group. Note: Box plots include median value line, mean (average) value (red point), whiskers for minimum and maximum values and outliers (*). The coefficient of anisotropy calculated as ratios between the total tangential and radial swelling were situated in the range of 1.3-2.4 for the SO assortments and 1.7-1.9 for AO_C assortments, being slightly lower than the value of 2.5 calculated for the NO employed in this research. The same trend was observed for shrinking. To conclude, the experimental data in this research indicate that increased swelling and shrinking could be expected for SO compared to NO, though the anisotropy of dimensional changes might be slightly reduced. These aspects are important in the design of furniture and other wood products. The values of FSP calculated based on Equation (3) and swelling and shrinking coefficients for 1% variation in the MC, calculated based on the total swelling and shrinking coefficients and corresponding FSP values, are cumulated in Table 3.  
It can be observed that SO presents higher FSP values (34-45%) compared to NO (27) and AO (24-25). The variation in this property for all the studied assortments and variability and dispersion of individual data within each group is highlighted by the boxplots in Figure 5.  
Figure 5: Box plots of FSP values, illustrating the variation in this property among the different assortments of oak wood and dispersion of data in each group. Note: Box plots include median value line, mean (average) value (brown point), whiskers for minimum and maximum values and outliers (*). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Wood Material**} & \multirow{2}{*}{**FSP,**} & \multicolumn{3}{c}{**Swelling Coefficients**} & \multicolumn{3}{c}{**Shrinkage Coefficients**} \\  & & & **for 1\% W Variation** & & **for 1\% W Variation** & \\ \cline{2-9}  & & \(K_{\alpha,\alpha\prime}\) **\%** & \(K_{\alpha,\gamma\prime}\) **\%** & \(K_{\beta,\alpha\prime}\) **\%** & \(K_{\beta,\alpha\prime}\) **\%** & \(K_{\beta,\alpha\prime}\) **\%** & \(K_{\beta,\gamma\prime}\) **\%** \\ \hline
**SO\_S1** & 34 & 0.25 & 0.31 & 0.61 & 0.02 & 0.22 & 0.26 & 0.48 \\ \hline
**SO\_S2a** & 45 & 0.19 & 0.41 & 0.66 & 0.02 & 0.18 & 0.32 & 0.48 \\ \hline
**SO\_S2b** & 43 & 0.22 & 0.45 & 0.75 & 0.02 & 0.21 & 0.33 & 0.53 \\ \hline
**SO\_S3** & 34 & 0.19 & 0.45 & 0.69 & 0.02 & 0.19 & 0.35 & 0.53 \\ \hline
**AO\_C1\_C2** & 24 & 0.25 & 0.44 & 0.73 & 0.01 & 0.27 & 0.40 & 0.65 \\ \hline
**AO\_C3** & 25 & 0.22 & 0.41 & 0.68 & 0.02 & 0.22 & 0.38 & 0.60 \\ \hline
**NO** & 27 & 0.20 & 0.50 & 0.75 & 0.01 & 0.20 & 0.38 & 0.58 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Fibre saturation point, swelling and shrinkage coefficients for 1% moisture content (W) variation, \(K_{\alpha}\), \(K_{\beta}\). According to [3; 4] and literature cited herein, an increase in affinity to water might be attributed to a higher amount of the amorphous part of cellulose in subfossil oak and \"freer bonding sites in cellulose\" due to hydrolysis of hemicelluloses. FTIR investigations of our samples (not included in this paper) highlighted the prevalent degradation of hemicelluloses in subfossil wood so the above explanation might apply. However, it has to be highlighted that the calculation method employed was conceived for recent wood and might not be fully applicable for subfossil or aged woods due to the chemical changes in the cell walls.