## 3 Results
### Control Specim Analysis and Experimental Data Processing
#### 3.2.2 Type 2 Test Specimens  
1. Physicochemical studies  
All samples were analyzed using optical microscopy, which revealed aspects related to efficiency and compatibility in the test specimens. Three surfaces were studied, putty, matte gold, and glossy gold, allowing for a comparison of the morphology of the different putties and their microscopic behavior after the aging cycles. Gloss measurements were also carried out on the gilded surfaces to assess changes in surface sheen. * **Gloss. ** Gloss measurements were also carried out on the gilded surfaces of Type 2 specimens, allowing for the evaluation of optical efficiency and compatibility with the burnished metal leaf. The variation in gloss was assessed using a KONICA MINOLTA(r) Multi Gloss 268A portable glossmeter (Konica Minolta(r), Inc., Tokio, Japan), which features three reflectometer geometries (20\({}^{\circ}\), 60\({}^{\circ}\), and 85\({}^{\circ}\)) and complies with ISO 2813 [48]. The measurement window of the device was positioned to ensure full contact with the specimen surface, and five readings were taken per sample. **Results**. Analysis of the data revealed notable differences in the ability of certain fillers to maintain or enhance surface gloss. Most materials exhibited gloss values between 83 and 97 gloss units (GU). However, two fillers displayed markedly distinct behavior: M3 showed the highest gloss level, exceeding 110 GU, suggesting that the surface of this filler interacted favorably with the gold leaf, possibly due to its texture and composition. In contrast, M4 stood out for its low gloss value (~60 GU), indicating that its surface may not be suitable for applications requiring a high-luster gold finish. This may be related to factors such as porosity, bole absorption, or the chemical composition of the filler. These results suggest that when using this base material, additional surface treatments may be necessary to improve optical performance. Figure 8: Graph of variations in Shore C hardness measurements of tested fillers. Source: Authors’ own elaboration, DorART Project, 2025. 2 Mechanical studies
* **Abrasion of the fine gold layer and stability of the water gilding on the tested materials. ** The efficiency and compatibility of the materials were assessed by evaluating their abrasion resistance using a Taber(r) 5750 Linear Abraser (North Tonawanda, New York, US), in accordance with the UNE-EN ISO 7784-3 standard [49]. The tests were carried out under controlled conditions, with an abrasion path length of 1.27 cm and a speed of 60 cycles per minute. An H-10 hardness wearaser tip was used to simulate surface wear on the specimens. **Results**. Burnished gilding demonstrated greater mechanical stability and better resistance to abrasion, whereas matte gilding proved more vulnerable under the same test conditions. These differences are clearly illustrated in Table 4, which presents surface micrographs of M6 specimens across aging cycles after abrasion testing. The specimens that showed the best resistance to abrasion were M2, M4, M8, and M9. In these cases, the wear was mostly limited to the gold leaf, exposing the underlying bole layer. Occasional losses of bole were observed, but the base material (putty) remained intact, indicating that these fillers provided higher mechanical stability and stronger adhesion between layers. Conversely, specimens M1, M3, M5, M6, and M7 exhibited less favorable performance, with significant losses affecting not only the gold leaf but also the bole layer and, in some cases, the base material. M1 exhibited the most pronounced deterioration, suggesting a lower mechanical strength of both the gilded surface and the overall system. M5, although initially resistant to abrasion, began to show greater degradation from the third cycle onward, possibly due to a progressive loss of internal cohesion or reduced adhesion between layers.