## 2 Materials and Methods  
### Experimental Samples  
The sample selection was based on the most frequent use of these wood species in the joinery and carpentry industry (Table 1). From each wood type, 30 samples were prepared with dimensions 250 \(\times\) 90 \(\times\) 20 mm. The moisture content of each sample was determined gravimetrically according to the recommendations of [43; 44]. The density of the wood samples was determined according to [45]. The group of softwood samples (spruce, red spruce, and pine) has similar applications, namely, in the production of fibreboards, particleboards, plywood, and veneers; it can be used as building and construction timber indoors and outdoors, as well as for ship and mast construction [46]. Hardwood is a feedstock for the furniture industry [47]. The experiments were conducted with 5 fungicide coatings from different manufacturers with different chemical compositions (Table 2) and the flame retardant HRP. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Chemical** & **Type** & **Appearance** & **Density (g-cm\({}^{-3}\))** & **Component** & **Amount (\%)** \\ \hline \multirow{6}{*}{FUN [48]} & fungicide & & & N-(3-aminopropyl)-N- & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } \\  & & & & dodecylpropane-1,3- & \\  & fungicide & & & diamine(molecular & \textless{}3 \\  & & & formula C\({}_{18}\)H\({}_{41}\)N\({}_{3}\)) & \\  & Colourless & & lactic acid & \textless{}3 \\  & transparent liquid & & 2,2\({}^{\prime}\)-oxydiethanol, amines, coco & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } \\  & & & alkyldimethyl, N-oxides & \textless{}2 \\  & & & propiconazole & \textless{}2 \\  & & & cypermethrin & \textless{}0.25 \\ \hline \multirow{6}{*}{BOCH FUN [49]} & fungicide & & alkyl(C12–16) dimethylbenzyl & \textless{}20 \\  & Colourless & & ammonium chloride & \textless{}2 \\  & transparent liquid & & 2-(2-butoxy)ethanol & \textless{}2 \\  & & & phosphoric acid & \textless{}0.5 \\  & & liquid & propiconazole, tebuconazole & \textless{}0.3 \\  & & & N-(3 aminopropyl)-N- & \textless{}0.25 \\  & & & dodecylpropane-1,3-diamine & \textless{}0.1 \\  & & & Cypermethrin & \textless{}0.1 \\ \hline \multirow{6}{*}{BOCH [50]} & fungicide & & alkyl/benzyl (C12–16) & \multirow{6}{*}{\begin{tabular}{} \end{tabular} } \\  & & Colourless & dimethylbenzyl & \textless{}5.3 \\  & & transparent liquid & ammonium chloride & \textless{}5.3 \\  & & & boric acid & \textless{}5.3 \\  & & & 2-aminoethanol & \textless{}2 \\ \hline \multirow{6}{*}{NAP [51]} & fungicide & \begin{tabular}{} \end{tabular} & 0.9–1.10 & \multirow{6}{*}{\begin{tabular}{} \end{tabular} } \\  & & of light yellow & & 2-(2-butoxyetoxy)ethanol & \multirow{6}{*}{\
\begin{tabular}{} \end{tabular} } \\  & & & leuconazole (ISO) & \\  & & & cyclohexanone oxime & & \\  & & & cypermethrin & & \\ \hline \multirow{6}{*}{AQUA [52]} & fungicide & & & D-glucose, oligomers, decyclooctyl & \multirow{6}{*}{
\begin{tabular}{} \end{tabular} } \\  & & & glycosyloides, mixture of 5-chloro-2- & \\  & & methyl-2H-isothiazol-3-one and & & \\  & & & methyl-2H-isothiazol-3-one & & \\  & & & propiconazole (ISO) & \textless{}1 \\  & & & 3-iodoprop-2-inylbutylcarbamate & \textless{}1 \\  & & & cypermethrin & \textless{}0.1 \\ \hline \multirow{6}{*}{HRP [53]} & flame retardant & & & ferric phosphate/Iron & \textless{} 30\% \\  & Light brown & & orthophosphate & \textless{}0.3\% \\  & odourless liquid & & citric acid & \textless{}1\% \\  & & octadecan-1-ol, ethoxylated & \textless{}0.5 & \\  & & reaction to fire & B-s1, d0 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Characteristics of fungicides and retardant coatings. The price of protective coatings varies depending on the seller and the size of the package. A 1 kg package of HRP costs around EUR 25-39, a 5 kg package of HRP costs around EUR 87-140. The price of fungicidal coatings is also very different, but they are cheaper than HRP. The prices of fungicidal coatings are approximately one-third the price of HRP.