## 3 Results and Discussion  
The values of initial and final moisture contents, density in an absolutely dry state and drying times for individual wood species and drying modes are shown in Table 3.  
The initial moisture content of the samples in both trees ranged from 66% to 70%. The required final moisture content was reached by hot-air drying at a temperature of 60 \({}^{\circ}\)C (Figure 1). The drying time of the maple samples was 48 h shorter than that of hornbeam. During high-temperature drying (120 \({}^{\circ}\)C), the final moisture contents were remarkably lower than the required values for both wood species. This was due to a very rapid loss of moisture in the area below the fiber saturation point (Figure 2) when the drying temperature was raised to 120 \({}^{\circ}\)C. In this drying mode, the final time was not affected by the wood. Figures 1 and 2 show the drying curves for the individual wood species and drying modes. \begin{table}
\begin{tabular}{l l l} \hline \(\Delta E^{*}<0.2\) & No visible difference \\ \(2>\Delta E^{*}>0.2\) & Small difference \\ \(3>\Delta E^{*}>2\) & Color difference visible with high-quality screen \\ \(6>\Delta E^{*}>3\) & Color difference visible with medium-quality screen \\ \(12>\Delta E^{*}>6\) & High color difference \\ \(\Delta E^{*}>12\) & Different colors \\ \hline \end{tabular}
\end{table} 
Table 2: The scale of \(\Delta E^{*}\)[24]. \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**Drying Mode**} & \multirow{2}{*}{**Samples**} & \multirow{2}{*}{\
\begin{tabular}{c} **Initial Moisture** \\ **Content** \(MC_{i}\) **(\%)** \\ \end{tabular} } & \multicolumn{2}{c}{**Final Moisture**} & \multirow{2}{*}{
\begin{tabular}{c} **Density in Absolutely** \\ **Dry State** **(kg\(\cdot\)m\({}^{-3}\))** \\ \end{tabular} } & \multirow{2}{*}{**Drying Time (h)**} \\ \cline{3-3} \cline{5-6}  & Hornbeam & 66.25 \(\pm\) 0.43 & 9.00 \(\pm\) 0.28 & 795.50 \(\pm\) 3.42 & 384 \\  & Maple & 65.54 \(\pm\) 0.64 & 9.36 \(\pm\) 1.46 & 579.92 \(\pm\) 4.81 & 336 \\ \hline \multirow{2}{*}{**120**} & Hornbeam & 68.14 \(\pm\) 0.22 & 1.71 \(\pm\) 0.14 & 799.10 \(\pm\) 2.90 & 168 \\  & Maple & 69.59 \(\pm\) 0.31 & 2.19 \(\pm\) 0.07 & 574.99 \(\pm\) 3.11 & 168 \\ \hline \end{tabular}
\end{table} 
Table 3: Data about drying modes, initial and final moisture contents, density in absolutely dry state and drying times. When comparing the drying curves between wood species, it can be seen that the maple samples dried faster than the hornbeam. According to [20], it could be that moisture losses are affected by different factors. According to the equation used to determine the moisture conductivity coefficient, density is the most influential factor, alongside the wood's structure and temperature. Therefore, the wood's density along with the treatment temperature, influence the drying curve. As the wood density increases, its moisture content conductivity decreases due to the relative reduction in the volume of the capillaries. This is the main reason for the slower drying of hornbeam. In high-temperature drying, this effect is compensated for by the increased drying temperature [20]. During hot-air drying (Figure 1), a difference was visible in both the area of free water and in the area of bound water. However, when the moisture content of the samples dropped below 50%, the differences in moisture losses between the wood species increased. Figure 1: Drying curves for hot-air drying mode (60 \({}^{\circ}\)C). Figure 2: Drying curves for high-temperature drying mode (120 \({}^{\circ}\)C). During hot-air drying (Figure 3), the largest changes in color coordinates occurred during the first 24 h. According to the values of the color difference in both wood species, a high color difference was found (Table 2). That is, the color changes were visible to the naked eye. For maple, the brightness value (\(L^{*}\)) decreased remarkably and the samples darkened most significantly up to 144 h of drying. After this point, the brightness did not change.