## 3 Results
### Contact Angle
The type of varnish used clearly influences the formation of the contact angle between the basecoating with a mean of 82.28\({}^{\circ}\) (1-7a) and the topcoating with a mean of 87.11\({}^{\circ}\) (1-14a), (\(p\)-value 0.0103271). Additionally, it was stated that line speed has equal importance on the formation of the contact angle with the same power of lamp. For example, the mean of 63.60\({}^{\circ}\) for 1-3d at 40 m/min in comparison to 70.85\({}^{\circ}\) for 1-3a at 25 m/min (\(p\)-value 0.0000077) or the mean of 77.23\({}^{\circ}\) for 1-7d at 40 m/min in comparison to 82.28\({}^{\circ}\) for 1-7a at 25 m/min (\(p\)-value 0.0058). The samples stay under the lamps longer, which affects the density of energy supplied to the process. Based on the value of the contact angle, a parameter characterizing the wetting process of the substrate (\(\gamma_{\mathrm{S}}\)) with the varnish products and the interlayer interaction was calculated. It indicates the possibility of systems with compatible relations between the individual layers. Preliminary analysis of the values of surface free energy influencing the adsorption, wetting, and adhesion processes to the most significant extent, being at the same time the effect of intermolecular interactions, indicates that the tested systems exhibited \(\gamma_{\mathrm{S}}\) values in the range of 32-51 m\(\mathrm{J}\)/m\({}^{2}\) (Figure 5). Regarding the theoretical assumptions of the adsorption theory of polymer adhesion to the substrate, the \(\gamma_{\mathrm{S}}\) value of the refined surface should be higher than that of the consolidated varnish. In the evaluated relations, this requirement was fulfilled. Based on literature data, for the HDF board, the values for beech wood (_Fagus sylvatica_ L.) of \(\gamma_{\mathrm{S}}\) = 67.6 m\(\mathrm{J}\)/m\({}^{2}\), \(\gamma_{\mathrm{S}}\)\({}^{\mathrm{d}}\) = 24.7 m\(\mathrm{J}\)/m\({}^{2}\), and \(\gamma_{\mathrm{S}}\)\({}^{\mathrm{P}}\) = 42.9 m\(\mathrm{J}\)/m\({}^{2}\)[16], on which the HDF board was based, were adopted. This allowed an indirect inference about the \(\gamma_{\mathrm{S}}\) value of the HDF board despite the use of adhesive and hydrophobic agents in its production. The obtained \(\gamma_{\mathrm{S}}\) values exceeded the relevant data determined for the varnish coatings under consideration. When evaluating the relations between the applied products, interlayer coatings were characterized by higher \(\gamma_{\mathrm{S}}\) values. The primer coatings can therefore be regarded as a  
Figure 5: Results of the surface free energy. typically intermediate factor in shaping the final adhesion. The application of topcoats resulted in a decreased surface energy. A clear influence of the dispersion component on the formation of \(\gamma_{\mathrm{S}}\) values was found. After the phase transformation of the products into solidified layers, the resulting varnish coatings were characterized by favorable interlayer adhesion and substrate adhesion. Unevenness and porosity increase the effective interaction surface between the surface forces of the substrate and varnish products and, therefore, increase the value of the work of adhesion of the varnish to the board compared to the work of adhesion and spreading of the varnish on a smooth surface. The work of adhesion (Wa) in the HDF-coat varnish system had a higher value (91.80-93.78 mJ/m\({}^{2}\)) than the work of adhesion of the topcoats to the primers (75.79 to 87.82 mJ/m\({}^{2}\)). The primer coatings can, therefore, be regarded as a factor typically facilitating the formation of the final adhesion. Considering the values of the dispersion component of the work of adhesion (Wad) for the systems under consideration, it was found that they were quite similar at 65 mJ/m\({}^{2}\), while the polar component of the work of adhesion (WaP) varied considerably.