## 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  
The total linear and volumetric swelling and shrinkage coefficients are presented in Table 2 and graphically illustrated by the box plots in Figure 4.  
It could be observed that, generally, higher total swelling and shrinking coefficients were determined for SO compared to NO. The average values of the total swelling coefficients determined for the different SO assortments varied in the ranges 20.9-32.4% (\(V\)), 6.4-9.4% (\(Ra\)) and 10.7-19.5% (\(Tg\)), with maximum values for the SO_S2b samples, which also presented the higher density. The corresponding values for NO were 20.0% (\(V\)), 5.4% (\(Ra\)) and 13.4% (\(Tg\)), respectively. The smaller tangential swelling and shrinkage coefficients for the SO_S1 assortment compared to recent oak NO must be also noted, which might be correlated with the higher density of the NO wood specimens investigated in this research. The total swelling and shrinkage coefficients of AO samples were close to those for recent oak. The values of total shrinkage obtained in this research, higher for SO compared to NO, as similarly reported in the literature, e.g., [2; 3; 4; 13], were situated in the characteristic intervals presented in [38] for subfossil oak and new oak. Some exceptions could be noted: slightly lower values of radial and tangential shrinkage for new oak and a single higher value of longitudinal shrinkage for SO. A remark has to be made on the high longitudinal swelling and shrinking coefficients of SO, especially the assortments SO_S2b (\(\alpha_{L\max}=1.2\), \(\beta_{L\max}=0.9\)) and SO_S2a (\(\alpha_{L\max}=1.0\), \(\beta_{L\max}=0.7\)), compared to NO (\(\alpha_{L\max}=0.5\), \(\beta_{L\max}=0.4\)). They might indicate the presence of tension wood [41]. The direct relationships between anatomical pattern, density and local swelling of oak wood were demonstrated [42]. The increased swelling of SO compared to recent oak could probably be due to the \"leaching of degradation products or inorganic compounds stored in wood during the fossilization process\" and chemical analysis of leaching water would be necessary in order to find out which compounds are responsible for the distinct swelling if subfossil oak is immersed in water [4]. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Wood**} & \multicolumn{4}{c}{**Total Swelling**} & \multicolumn{4}{c}{**Total Shrinkage**} \\ \cline{2-9}  & \(\sigma_{L\max}\) & \(\alpha_{Ra\max}\) & \(\alpha_{Tg\max}\), & \(\alpha_{V\max}\) & \(\beta_{L\max}\) & \(\beta_{Ra\max}\), & \(\beta_{Tg\max}\), & \(\beta_{V\max}\), \\  & \% & \% & \% & \% & \% & \% & \% & \% \\ \hline
**SO\_S1** & 0.7 \(\pm\) 0.3 & 8.4 \(\pm\) 1.5 & 10.7 \(\pm\) 1.3 & 20.9 \(\pm\) 1.4 & 0.7 \(\pm\) 0.4 & 7.6 \(\pm\) 1.2 & 9.0 \(\pm\) 1.2 & 16.4 \(\pm\) 1.0 \\ \hline
**SO\_S2a** & 1.0 \(\pm\) 0.3 & 8.5 \(\pm\) 1.0 & 18.4 \(\pm\) 1.2 & 29.6 \(\pm\) 1.8 & 0.7 \(\pm\) 0.3 & 8.0 \(\pm\) 0.7 & 14.3 \(\pm\) 0.8 & 21.7 \(\pm\) 1.1 \\ \hline
**SO\_S2b** & 1.2 \(\pm\) 0.7 & 9.4 \(\pm\) 0.7 & 19.5 \(\pm\) 0.8 & 32.4 \(\pm\) 1.7 & 0.9 \(\pm\) 0.6 & 8.9 \(\pm\) 0.5 & 14.4 \(\pm\) 0.6 & 22.7 \(\pm\) 1.0 \\ \hline
**SO\_S3** & 0.6 \(\pm\) 0.3 & 6.4 \(\pm\) 0.6 & 15.4 \(\pm\) 2.1 & 23.6 \(\pm\) 1.8 & 0.7 \(\pm\) 0.2 & 6.4 \(\pm\) 0.6 & 11.9 \(\pm\) 0.5 & 18.0 \(\pm\) 0.9 \\ \hline
**AO\_C1\_C2** & 0.3 \(\pm\) 0.1 & 6.1 \(\pm\) 1.3 & 10.5 \(\pm\) 1.5 & 17.6 \(\pm\) 1.4 & 0.2 \(\pm\) 0.1 & 6.5 \(\pm\) 0.9 & 9.7 \(\pm\) 0.9 & 15.6 \(\pm\) 0.7 \\ \hline
**AO\_C3** & 0.7 \(\pm\) 0.2 & 5.5 \(\pm\) 0.4 & 10.3 \(\pm\) 0.6 & 17.1 \(\pm\) 0.8 & 0.5 \(\pm\) 0.3 & 5.6 \(\pm\) 0.4 & 9.7 \(\pm\) 0.7 & 15.1 \(\pm\) 0.8 \\ \hline
**NO** & 0.5 \(\pm\) 0.3 & 5.4 \(\pm\) 0.9 & 13.4 \(\pm\) 1.0 & 20.0 \(\pm\) 1.4 & 0.4 \(\pm\) 0.4 & 5.4 \(\pm\) 0.8 & 10.2 \(\pm\) 1.3 & 15.3 \(\pm\) 1.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparative values of total swelling and total shrinkage coefficients of subfossil oak (SO), aged oak (AO_C), and new oak (NO)—average values and standard deviations.