## 2 Methodology  
These samples represent both softwood and hardwood (Table 1 and Figure 1a). The selection of samples was targeted. Two coniferous (spruce and red spruce) and two deciduous (oak and cherry) trees were selected. They were also chosen as representatives of softwood (spruce and red spruce) and hardwood (cherry and oak). The choice was also based on availability: the most abundant in the environment are spruce and oak, while the relatively poorly represented trees are red spruce and cherry. \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Parameters**} & \multicolumn{2}{c}{**Soft Wood**} & \multicolumn{2}{c}{**Hard Wood**} \\ \cline{2-5}  & **Spruce** & **Red Spruce** & **Cherry** & **Oak** \\ \hline Mass (g) & 84.19 \(\pm\) 3.22 & 130.05 \(\pm\) 1.81 & 121.11 \(\pm\) 7.24 & 131.37 \(\pm\) 3.17 \\ \hline Moisture (\%) & 6.64 \(\pm\) 0.78 & 7.24 \(\pm\) 0.55 & 7.10 \(\pm\) 2.17 & 7.51 \(\pm\) 0.69 \\ \hline Density (kg\(\cdot\)m\({}^{-3}\)) & 421 \(\pm\) 15.89 & 650 \(\pm\) 8.64 & 605.67 \(\pm\) 30.93 & 656.67 \(\pm\) 15.32 \\ \hline \end{tabular}
\end{table} 
Table 1: Basic parameters of experimental wood samples. Figure 1: (**a**) Experimental samples of oak (1D, 2D, 3D); of spruce (1S, 2S, 3S); of red spruce (1 CS, 2 CS, 3 CS) and cherry (1C, 2C, 3C) be front of experiment; (**b**) hot-plate device. Spruce is the most commonly used wood in our environment. Red spruce lumber is traditionally used mainly outdoors. Oak is the hardest wood in our environment with wide use. Cherry is a very popular wood in the furniture industry. Norway spruce (_Picea abies_ L.) is naturally widespread in Northern and Central Europe. In Slovakia, it was originally widespread in mountainous areas, predominantly on poorer soils above an altitude of 800 to 900 m [36]. Spruce wood has the widest application due to its excellent technical properties, superb workability, and large domestic resources [37; 38]. It is the most important wood for sawmill processing [39]. Spruce is mainly used in the production of furniture, as a raw material to produce plywood, slats, fiberboard, chipboard, etc. Additionally, spruce is a traditional and important raw material for the paper and pulp industry [40]. Red spruce (_Picea rubens_ [PERSON]), also called larch deciduous, is widely used [41], as it is well adapted to humid, cool climatic conditions [42; 43], but there are justified concerns about its future existence [44]. The main advantages of larch wood include its high hardness, longevity, resistance to water and moisture, and, most importantly, its resistance to alternating wet and dry conditions [45]. It is a durable construction timber [46]. Cherry (_Prunus avium_ L.) is a representative of fruit trees. It was historically used in Slovak sacral architecture [47]. Sweet cherry (_Prunus avium_ L.) is a tree widely cultivated in temperate regions for its tasty and healing fruits [48; 49; 50; 51]. Oak (_Quercus alba_) is a representative of high-density hardwoods [52] and the second most abundant deciduous species in Slovakia [53]. It is known for its extensive utilization in various applications [54]. The selected experimental wood samples were cut to a size of 100 \(\times\) 100 \(\times\) 20 mm and were treated at an initial temperature of 21 \({}^{\circ}\)C and a pressure of 100.56 kPa, either placed directly on the heating plate or on metal rings of 12 mm and 32 mm thickness. The experiments were part of a research task, and the sample sizes were the same for multiple experimental measures. The choice of the distance of the sample from the hot-plate surface was based on the technical possibilities of the test equipment. Wood is a thermal insulator. By placing wood on a hot plate, it is possible to observe the processes of thermal conductivity that take place on the surface of the sample. Subsequently, the choice of separation distance offers the possibility of spreading radiant heat. The choice of rings as extensions was deliberate.