## 3 Results
### Control Specim Analysis and Experimental Data Processing
#### 3.2.1 Type 1 Test Specimens
The results (Table 2) correspond to our own experimental tests, which were adapted from [PERSON] method for the study of paper surfaces [45] and conducted under controlled laboratory conditions, and as such, they do not represent values certified by manufacturers. The pH behavior of the different filler materials (M1 to M9) was evaluated over four successive cycles, and in all cases, a clear downward trend in pH was observed, indicating a general acidification of the medium. Although all the materials exhibited a decrease in pH over the course of the aging cycles, some of them--such as M5, M6, and M2--maintained relatively stable values, with the final values near or above pH 6.5. This suggests lower chemical reactivity and greater resistance to degradation under thermo-hygrometric stress. In contrast, other materials, such as M4, M7, and M9, showed more pronounced pH drops, with the final values close to or below pH 6.0, indicating higher susceptibility to chemical alteration over time. Despite the observed acidification, materials M5 and M6 maintained a stable physicochemical profile during the aging cycles. This behavior can be attributed to their formulation: both are based on low-reactivity thermoplastic polymers (Beva(r)) combined with inorganic fillers--calcium sulfate (CaSO\({}_{4}\)) in M5 and vermiculite in M6. These components are chemically stable and hygroscopically inert, which likely reduces their susceptibility to hydrolysis or oxidative degradation under thermo-hygrometric stress. Supporting this interpretation, both fillers also showed minimal variation in Shore C hardness and exhibited the lowest adhesion variability across all materials, with CV values of 0.00%. Figure 6: Graph of contact angle measurements of tested fillers. Source: Authors’ own elaboration, DorART Project, 2025. 2 Mechanical studies
* **Adhesion tests on wood substrates. ** Adhesion tests were used determine the coating's resistance to detachment. The adhesion strength of the reintegration fillers was evaluated following the specifications of ISO 4624:2003 [46], which defines the pull-off test method for assessing the adhesion of coatings to rigid substrates. An electronic adhesion tester (KN-10, Neurtek) was used for this purpose. This device is specifically designed for measuring the adhesion strength of paint layers, coatings, and building materials to their respective substrates. For each material, three replicates were tested. The procedure involved bonding a 20 mm diameter dolly to the surface under study using Araldite@ epoxy adhesive. After the manufacturer's specified curing time had elapsed, the instrument was then positioned on the dolly, and a progressive pull-off force was applied. At the point of failure, the device digitally recorded the maximum force exerted. The equipment operates within a range of 5 to 1000 kgf (0.05 to 10.00 kN). **Results**. Regarding efficiency and compatibility (Table 3), M1 exhibited high initial adhesion strength (8.23 MPa) and showed increased internal cohesion after aging, maintaining cohesive failure throughout the cycles. Fillers M2, M3, and M9 demonstrated a progressive loss of internal cohesion across successive cycles. M2 initially showed high adhesion values (>7.94 MPa), but its adhesion evolved to exhibit partial cohesive failure (40-60%) and signs of structural degradation, including a sharp drop in adhesion during Cycle 3 (2.94 MPa). M3 maintained relatively stable adhesion values (ranging from 6 to 7.4 MPa), though with a shift toward adhesive-cohesive failure, reaching only 20% cohesive failure by Cycle 4. M9 presented stable mechanical behavior in the first cycles (5-5.39 MPa), with predominantly cohesive failures (75-100%), indicating a strong bond to the substrate, although a slight decline in adhesion and cohesion was observed in later cycles. The coefficients of variation (CV%) for adhesion values were calculated. Values > 15% were observed in some materials, notably M2 and M4, indicating heterogeneous internal cohesion or degradation trends under thermo-hygrometric cycles.