# Effect of Spruce Wood Density on Selected Fire-Technical Parameters during Thermal Loading
## 3 Results and Discussion
The maximum mass loss rate of the R1-LD samples was reached at a testing time of 50 s with a value of 0.158%\(\cdot\)s\({}^{-1}\), while the R1-HD samples had their highest mass loss rate at a testing time of 70 s with a value of 0.077%\(\cdot\)s\({}^{-1}\). However, differences in the mass loss rates were still observed up to a testing \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline Samples Treated with Retardant 1, Difference in Density 243.69 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 107.64 & 107.64 & 39.05 & 1.56 \(\times\) 10\({}^{-5}\) & Influence \\ Residuals & 15 & 41.34 & 2.76 & & & & \\ \hline \hline Samples Treated with Retardant 2, Difference in Density 50.65 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 0.424 & 0.4245 & 0.453 & 0.51 & No influence \\ Residuals & 16 & 14.982 & 0.9364 & & & \\ \hline \hline Samples Treated with Retardant 3, Difference in Density 8.44 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 0.012 & 0.0124 & 0.011 & 0.919 & No influence \\ Residuals & 13 & 15.175 & 1.1673 & & & \\ \hline \hline  & & & & & & \\ \end{tabular}
\end{table} 
Table 4: ANOVA of sample mass loss at 300 s testing time. \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline Samples Treated with Retardant 1, Difference in Density 243.69 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 82.23 & 82.23 & 28.38 & 8.46 \(\times\) 10\({}^{-5}\) & Strong \\ Residuals & 15 & 43.46 & 2.90 & & & \\ \hline \hline Samples Treated with Retardant 2, Difference in Density 50.65 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 0.011 & 0.0105 & 0.006 & 0.939 & No influence \\ Residuals & 16 & 27.743 & 1.7340 & & & \\ \hline Samples Treated with Retardant 3, Difference in Density 8.44 kg\(\cdot\)m\({}^{-3}\) & & & & & \\ \hline \hline  & Df & Sum Sq & Mean Sq & F value & Pr (\(>\)F) & Influence \\ Density (\(\rho\)) & 1 & 1.011 & 1.011 & 0.645 & 0.436 & No influence \\ Residuals & 13 & 20.372 & 1.567 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: ANOVA of sample mass loss at 600 s testing time. time of about 300 s (R1-LD samples had a noticeably higher one). After this time, the mass loss rates of both the higher- and lower-density samples were virtually identical due to the retardant treatment of the samples, which prevented them from spontaneous combustion and had a significant effect on the mass loss rate. Samples treated with retardant 2, which had a difference in densities of approximately 50 kg\(\cdot\)m\({}^{-3}\), and samples treated with retardant 3, with a difference in densities of about 8.5 kg\(\cdot\)m\({}^{-3}\), showed significantly lower variations in the mass loss rates (Figures 6 and 7), which were negligible. The differences primarily occurred in the maximum mass loss rate within the initial seconds, with a difference of 0.002%\(\cdot\)s\({}^{-1}\) for samples treated with retardant 2 and 0.010%\(\cdot\)s\({}^{-1}\) for samples treated with retardant 3. Consequently, the average mass loss rate of the higher- and lower-density samples was virtually identical throughout the experiment. These differences also had no significant effect on the total mass loss, as confirmed by Tables 4 and 5, where the dependence of the mass loss on the sample density was not evident for samples R2 and R3. Figure 5: Average mass loss rate of samples treated with retardant 1 over time. Figure 6: Average mass loss rate of samples treated with retardant 2 over time. From the point of view of fire spread, not only the maximum value of the mass loss rate was significant, but also the time to reach this value.