## 3 Results and Discussion
### Monitoring the Effect of Selected Fungicidal Coatings on the Effectiveness of HRP
Its mass-loss values are the lowest. Figure 5: Presentation of wood samples after the experiment. The order of wood species is sorted from left to right as follows: 1 row—SM (spruce) and SMR (red spruce); 2 row—JAS (ash) and BOR (pine); 3 row—DUB (oak) and BUK (beech). A comparison of the mass losses with respect to the species (Figure 7) produces comparable results in terms of percent loss (0.04-0.09%). JAS wood can be considered the weakest wood sample where we observed the highest mass loss (Figure 7), and the value of mass loss of all fungicide coating samples is in the range of 0.08-0.09%. Ash is generally considered excellent wood with a constant energy value for heating all types of appliances [72]. The softwoods spruce and pine demonstrate the highest variance in mass loss in terms of the impact of fungicide coatings. Figure 6: Boxplot of the variance of mass loss for individual fungicide coatings. Legend: UN—untreated with fungicide coating, 2—untreated with fungicide coating, 3—Fun (red), 4—Boch Fun (green), 5—Boch (dark blue), 6—Nap (light blue), 7—Aqua (violet). Figure 7: Mass loss obtained by small flame test and comparison of flame spreads in 30 s.  
The theoretical assumption of NAP and AQUA samples, based on their chemical composition, as weaker fungicidal coatings relative to the others was confirmed. BOCH FUN has the highest amount of active fungicidal ingredients (Table 2) and achieves the most satisfactory results in terms of mass loss. At the same time, BOCH FUN wood samples present shorter flame-spread values than the other samples (Table 5 and Figure 7). The BOCH coating achieves the lowest flame-spread values (Figure 8). BOCH and BOCH FUN share a common active fungicidal ingredient: alkyl/benzyl (C12-16) dimethylbenzyl ammonium chloride (Table 2). BOCH has an additional retardant boric acid added to its structure (Table 2). Boric acid is also used in fire retardants [73; 74; 75; 76]. The presence of boric acid can enhance the retardant effect of HRP coating, manifested by slower flame spread (Figure 8). The aforementioned fact can also be seen in the boxplots that do not consider the influence of the wood species (Figure 8). this wood is a suitable fuel for boilers [77]. [PERSON] et al. [78] conducted experiments with thermally modified oak and fungicide coating. They confirmed the effect of thermally modified oak on increasing resistance to biological pests. This was also supported by the research of [PERSON] and [PERSON] [79]. They performed experiments on pine and oak in identical conditions but used fungicide preparation LAZ with the same chemical composition as NAP and AQUA. [PERSON] et al. [80] considered continuous mass loss measurement as the main evaluation criterion for retardant effectiveness. If a retardant indicated a mass loss of up to 5% within 60 s, it could be considered satisfactory. A mass loss of up to 5% represented the retardant decomposition and the wood did not burn. The second criterion was a total mass loss of up to 3 min. The experimental samples were beech and retardant coating, and the experiment time was 3 min. Our results, confronted with the requirements of [80], would meet the above criteria. However, extrapolation of the results from the 30 s to 60 s would not be possible because the mass loss for some samples with FUN and BOCH FUN coating would not reach 1%. The treated spruce samples demonstrate low values of mass loss, comparable to oak (Figure 7), but on the other hand, the highest values of flame spread (Figure 7). [PERSON] et al. [81] conducted research on the effectiveness of selected retardants applied to spruce samples. The samples were exposed to flame for 5 min. The selection of retardants was based on their composition (polyurethane--polyether polyol + nanosilica) and presented mass losses of 10%. [PERSON] et al. [82] performed a combination of surface treatment and thermal loading experiments in reverse order. First, the samples were thermally modified and then exposed to fungi.