## 3 Results and Discussion
### Effect of the Filler on the Abrasion Resistance Properties of the Coatings  
The effect of the wax-based additive on abrasion resistance properties was assessed using a scrub test, with results depicted in Figure 13. The graph shows the evolution of the loss in coating mass per unit area, defined as L, and calculated according to the formula:  
\[\text{L}=(\text{m}_{0}-\text{m}_{\text{n}})/\text{A} \tag{2}\]  
where m\({}_{0}\) and m\({}_{\text{n}}\) represent the weight of the sample before the test and after the nth cycle of scrubbing, respectively, while A denotes the surface area affected by the abrasion caused by the movement of the abrasive sponge. Since the test simulates mild scrubbing processes like repetitive surface cleaning rather than aggressive abrasion, initial distinctions among sample results become discernible only after the first 250 cycles, gradually magnifying as the test progresses. Indeed, it is evident that the mass lost during the test by sample G0 consistently exceeds that of the three composite coatings. This outcome underscores the effective protective function provided by the wax-based filler. By the conclusion of the test, the enhancement achieved by the 5 wt.%  
Figure 13: Evolution of the mass loss per unit area L during the scrub test. \begin{table}
\begin{tabular}{c c} \hline \hline
**Sample** & \(\boldsymbol{\Theta}\) (\({}^{\circ}\)) \\ \hline G0 & \(51.6\pm 2.2\) \\ G5 & \(59.9\pm 2.9\) \\ G10 & \(63.4\pm 3.2\) \\ G10U & \(61.8\pm 3.5\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of the contact angle measurements (\(\theta\)). and 10 wt.% of wax, in terms of reducing mass loss compared to the reference sample G0, equated to about 13% and 19%, respectively. Similar findings have been previously documented in studies examining the protective function of wax-based fillers in wood paints [32; 34]. However, other literature on the utilization of bio-based additives has not consistently exhibited such reinforcing effects. For instance, polyamide 11 powders show less conspicuous contributions [68], while cellulose fibers may even diminish protective performances due to agglomeration issues of the additive [35]. Consequently, wax-based powders emerge as promising reinforcing fillers [86], often showcasing superior protective performances compared to other bio-based additives for wood paints available in the market [3]. In conclusion, the UV absorber does not demonstrate any notable impact on abrasion resistance. The performance of sample G10U remains comparable to that of samples G5 and G10, indicating that the presence of the UV absorber does not significantly alter the abrasion resistance properties observed in the coatings. Certainly, the abrasive processes can impact the aesthetic qualities of the coatings. Therefore, the color and gloss consistency of the samples were monitored throughout the scrub test. Figure 14a illustrates the progression of color change in the samples. Given the notably low values observed, it can be concluded that the abrasive phenomenon does not significantly influence the color of the bio-based additive, which retains its green-yellow hue consistently throughout the test. The abrasive process does indeed influence the reflectance properties, as evidenced by the graph depicting the evolution of gloss in Figure 14b. The acrylic matrix experiences a reduction in reflectance (as observed in sample G0), whereas the composite coatings demonstrate a slight increase in gloss throughout the abrasive test. This phenomenon is less pronounced in samples G10 and G10U, where the high concentration of wax-based filler maintains strong opacity, thereby mitigating the effects on gloss. These phenomena can be elucidated by the morphological changes induced by the abrasion process of the scrub sponge, as indicated by the surface roughness measurements depicted in Figure 14c. The graph illustrates the progression of roughness values both parallel (Ra //) and perpendicular (Ra \(\perp\)) to the fibers of the wooden substrate.