## 3 Results and Discussion  
### Degree of Checking  
#### 3.1.1 Board Cross-Section  
Mean values of number of observations and maximum depth of checks along or across growth rings on the pit side, bark side or in the core of 'exposed' control and TM boards are shown in Table 3. The table also shows percentage occurrence of boards with checks in the cross-section per sample, because boards with cross-sections free of checking were excluded when calculating mean values. Examples of checks across (white arrows) and along (orange arrows) growth rings in boards' cross-sections after weathering are shown in Figure 4. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{4}{c}{**Control**} & \multicolumn{4}{c}{**TM**} \\ \cline{2-10}  & **All** & **Pith up** & **Bark up** & **Edge** & **all** & **Pith up** & **Bark up** & **Edge** \\ \hline \multicolumn{10}{c}{ACROSS RINGS} \\ \hline \multirow{3}{*}{pith side} & 3 c  & 4  & 2 a  & 1 a  & 3 c  & 4 a  & 2 a  & 2 b  \\  & 4 a  & 6 a  & 2 a  & 7 a  & 8 a  \\  & (48\%) & (75\%) & (36\%) & (32\%) & (68\%) & (90\%) & (63\%) & (50\%) \\ \hline \multirow{3}{*}{bark side} & 3 & 5 a  & 4 a  & 3  & 2 a  \\  & 7 c  & 2 & 9 & 7 & 7 c  & 6 a  & 7 a  & 7 a  \\  & (88\%) & 5(79\%) & (86\%) & (100\%) & (98\%) & (97\%) & (100\%) & (96\%) \\ \hline \multirow{3}{*}{core} & 1 c  & 1 n/a  & 4 c  & 3 a  & 2 a  & 6 a  \\  & **17 c**  & **17 n/a ** & **17 n/a ** & **27 c**  & **24 a ** & **35 a ** & **25 a ** \\  & (1\%) & (4\%) & (4\%) & & (18\%) & (21\%) & (11\%) & (21\%) \\ \hline \multicolumn{10}{c}{ALONG RINGS} \\ \hline \multirow{3}{*}{pith side} & 3 & 3 a  & 2 a  & 4 a  & 4 [a  & 3 a  & 5 a  \\  & **3**  & 4 a  & **3 a ** & **10 a ** & **11 a ** \\  & (57\%) & (54\%) & (36\%) & (82\%) & (93\%) & (100\%) & (81\%) & (96\%) \\ \hline \multirow{3}{*}{bark side} & 2 c  & 2 n/a  & 2 n/a  & 2 c  \\  & 3 c  & 3 n/a  & 3 n/a  & 7 c  & 9 a  & 5 a  \\  & (5\%) & (0\%) & (4\%) & (11\%) & (39\%) & (31\%) & (37\%) & (50\%) \\ \hline \multirow{3}{*}{core} & 1 c  & & 1 n/a  & 3 c  & & & 3 n/a  \\  & **9 c**  & (0\%) & (0\%) & **9 n/a  & **25 c ** & (0\%) & (0\%) & **25 n/a ** \\  & (1\%) & & & & (4\%) & (1\%) & (3\%) & (3\%) & (50\%) \\ \hline \hline \end{tabular}  
* No significance difference (\(p>0.05\)) between groups (pith up, bark up or edgewise) within control and TM boards is indicated with the same letter (Kruskal–Wallis test). c No significant difference (\(p>0.05\)) between ‘all’ exposed control and TM boards is indicated with the same letter (Wilcoxon rank sum test). n/a Not applicable.  
\end{table} 
Table 3: Checks in cross-section of ‘exposed’ control and TM boards for all boards and per group: mean values of number of observations [no.] and maximum depth [mm] (in bold), and percentage [%] in parenthesis. Figure 4: Examples of checks across (white arrows) and along (orange arrows) growth rings in crosscuts of ‘exposed’ boards after weathering: (**a**) control board with checks across rings on bark side, (**b**) TM board with internal checks across rings and (**c**) TM board with checks along and across annual rings on pith and bark side. Checks across growth rings occurred more often in TM boards than control boards and were more common on the bark side than on the pith side (Table 3). This is consistent with a previous study wherein surface checking of spruce and pine TMT was evaluated after 3 wetting cycles [49]. The maximum depth of checks across rings was equal between TM and control boards on the bark side, but on the pith side, checks were significantly deeper for TM than control boards (Table 3). Twenty seven percent (27%) of the TM boards enclosed pith within the cross-section, whereas this was only 6% for control boards. This may explain why checks across rings on pith sides occurred more often and were larger for TM boards, since checking is more severe when pith is present [46; 47]. Table 3 also shows that, in contrast to control boards, approximately 20% of the TM boards had internal checks across growth rings.