## 3 Results and Discussion
### Monitoring the Effect of Selected Fungicidal Coatings on the Effectiveness of HRP  
The coating, Ferric phosphate-based HRP, reduced mass loss during heat loading of the wood surface (Figure 4). The requirements for wood products also specify the biodegradation of wood, so further research was focused on the effect of the combination of protective coatings (Table 4). Fungicide products were selected on the basis of their practical application. The procedure for treating wooden elements with fungicidal coatings was designed according to the manufacturers' requirements. The subsequent HRP surface treatment should increase the thermal stability of the samples (Figure 5). The results obtained (Table 4) demonstrate a reduction in the mass loss of the samples compared to a simple HRP treatment only. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Name** & **Untreated (\%)** & **FUN (\%)** & **BOCH FUN (\%)** & **BOCH (\%)** & **NAP (\%)** & **AQUA (\%)** \\ \hline SM & 0.06 \(\pm\) 0.0132 & 0.048 \(\pm\) 0.0132 & 0.038 \(\pm\) 0.0263 & 0.058 \(\pm\) 0.0172 & 0.042 \(\pm\) 0.0116 & 0.066 \(\pm\) 0.0089 \\ \hline SMR & 0.05 \(\pm\) 0.004 & 0.04 \(\pm\) 0.0109 & 0.052 \(\pm\) 0.0248 & 0.05 \(\pm\) 0.0063 & 0.051 \(\pm\) 0.0116 & 0.058 \(\pm\) 0.0074 \\ \hline BOR & 0.097 \(\pm\) 0.029 & 0.048 \(\pm\) 0.004 & 0.048 \(\pm\) 0.004 & 0.059 \(\pm\) 0.023 & 0.082 \(\pm\) 0.016 & 0.064 \(\pm\) 0.010 \\ \hline JAS & 0.096 \(\pm\) 0.008 & 0.085 \(\pm\) 0.012 & 0.088 \(\pm\) 0.018 & 0.078 \(\pm\) 0.007 & 0.092 \(\pm\) 0.016 & 0.088 \(\pm\) 0.009 \\ \hline BUK & 0.084 \(\pm\) 0.008 & 0.062 \(\pm\) 0.014 & 0.056 \(\pm\) 0.018 & 0.068 \(\pm\) 0.011 & 0.082 \(\pm\) 0.007 & 0.072 \(\pm\) 0.008 \\ \hline DUB & 0.066 \(\pm\) 0.010 & 0.046 \(\pm\) 0.004 & 0.054 \(\pm\) 0.008 & 0.056 \(\pm\) 0.014 & 0.07 \(\pm\) 0.022 & 0.058 \(\pm\) 0.021 \\ \hline \end{tabular}
\end{table} 
Table 4: Mass change of selected treated wood samples after 30 s of flame exposure. \begin{table}
\begin{tabular}{c c c c c} \hline
**Sample** & **N** & **Mean** & **Standard Deviation** & **Variance** & **Standard Error** \\ \hline Table 1\_2 & 30 & 0.0756666667 & 0.02269487764 & 0.000515057471 & 0.004143498808 \\ \hline Table 1\_3 & 30 & 6.61 & 1.12505938541 & 1.26575862069 & 0.205406801307 \\ \hline
**Source** & **DF** & **Sum of Squares** & **Mean Square** & **F Value** & **_p_ Value** \\ \hline Model & 1 & 640.462681667 & 640.4622681667 & 1011.570709733 & 2.100791912 \(\times\) 10\({}^{3}\) \\ \hline Error & 58 & 36.72193667 & 0.633136839081 & \\ \hline Total & 59 & 677.184618333 & \\ \hline \end{tabular}
\end{table} 
Table 3: One-way ANOVA analysis of the dependence of mass loss and flame spread on tree species. The experimental results were used to search for a significant dependence of the effect of fungicidal coatings on the retardant effectiveness. The variability of the obtained results was monitored by the QtiPlot software program [67]. The boxplot (Figure 6) indicated the variance of the mass-loss results in terms of fungicide-coating application. Boxplot 2 presents the mass loss of untreated samples by coatings, where the data are the highest (Table 4) and most scattered. It results from the variation in the type of wood samples specified in Figure 4. At the same time, the highest proportion of mass loss is observed for the untreated samples relative to the samples treated with fungicide coating. Based on the results, the influence of fungicidal coatings on the effectiveness of flame retardant can be accepted. Another large scatter of results can be seen in boxplot 6 (Figure 6), which presents the fungicide coating NAP (glucose and alcohol-based). A stable effect can be observed with the fungicidal coating BOCH, i.e., boxplot 4, where the mass-loss values are virtually identical. The FUN coating (boxplot 3, Figure 6) is comparable to the above results. Both coatings have N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine as the active ingredient. In terms of coating efficacy, regardless of the species, FUN has the most satisfactory result.