## 3 Results and Discussion
The highest values were measured for the lowest temperature (200/20\({}_{\rm R}\)--68.2\({}^{\circ}\); 200/20\({}_{\rm T}\)--70.0\({}^{\circ}\)), the higher the temperature was used, the worse CA, which is in line with previous results [11], where contact heating was also used for the preparation. As a rule, the wettability of heat-treated wood decreases [7; 21; 30]. Heat treatment of beech blocks were performed by [PERSON] et al. (2005) in France, in a reactor placed in an oven, the wood surface started to be hydrophobic (CA > 90\({}^{\circ}\)) after 120 \({}^{\circ}\)C [21]. CA characterized on heat-treated beech wood at 240 \({}^{\circ}\)C in an industrial oven showed that the variation after and before processing (\(\Delta\theta_{\rm a}=16.2^{\circ}\)) was low compared with other species (spruce = 44.7\({}^{\circ}\), pine = 62.4\({}^{\circ}\) poplar = 85.8\({}^{\circ}\)) [28]. The value of \(\Delta\theta_{\rm a}\) for beech processed by contact heating for radial specimens (\(\Delta\theta_{\rm a}=200/20\)k--REF\({}_{\rm R}\)) was 24.0\({}^{\circ}\) and 5.6\({}^{\circ}\) for tangential (\(\Delta\theta_{\rm a}=200/20\)t--REF\({}_{\rm T}\)). The average value of \(\Delta\theta_{\rm a}\) corresponded to 14.8\({}^{\circ}\), which was more or less in the good agreement previous results [31]. The effect of processing direction is obvious. Characteristics of dynamic wetting process for two different heat-treated (max. 205 \({}^{\circ}\)C) North American wood species, white ash and soft map, in axial, radial and tangential directions were studied and CA values were in all cases were higher for heat-treated wood than for untreated [32], this is in line with our results. Nevertheless, these results suggest that the difference between the CA in radial and tangential directions are not significant. In contrast, the behavior of CA in tangential and radial beech samples shows large differences. The lowest contact angles were measured on the surfaces that were charred at the highest temperatures (400 \({}^{\circ}\)C). The charring increased the hydrophobic behavior more in radial specimens. The exception was sample 400/1\({}_{\rm R}\), where CA decreased much faster than in the others; after 7 s its CA results were worse than the reference. Tangential specimens  
Figure 3: Contact angle of the radial (**A**) and tangential (**B**) one-sided charred specimens. showed better values of CA than REFT at \(200/20\)T, \(250/4\)T and \(250/6\)T. The rest have CA values that are the same as the reference (\(300/4\)T and \(350/1\)T), or even worse (\(300/2\)T, \(350/2\)T, \(400/1\)T and \(400/0.5\)T). The sample REFT had a relatively high CA on average, but the standard deviation was 14.11 after 10 s and 16.04 after 150 s (the highest initial measured CA is \(87^{\circ}\) and the lowest \(32^{\circ}\)). The results suggest that the surface properties of the tangential samples varied considerably. Principally, the values of radial standard deviation increased quite steadily with increasing observation time; the higher the temperature and time of charring, the greater the increase in deviation (\(250/4\)R = 0.30; \(400/1\)R = 10.32). In contrast, tangential samples (except REFT) show standard deviation values that are very similar, regardless of the treatment method (\(250/4\)T = 0.55; \(400/1\)T = 2.69). In general, polymeric materials are semi-crystalline with co-existing amorphous and crystalline phases. They show a certain degree of structural order, expressed by a degree of crystallinity from 40% to 90% (100% is never possible in processing conditions). Most wood-derived cellulose is crystalline [3]; due to the effect of pyrolysis, the crystallinity increases. The higher hydrophobicity of heat-treated wood can be explained by degradation of the amorphous region and an increase in cellulose crystallinity with temperature since the sorption of water by amorphous region is higher than for crystalline cellulose.