## 3 Results and Discussion
### Results of Cleaning Tests on Mock-Ups
\end{table}
Table 4: _Cont._The tests have been successful in identifying both advantages and disadvantages for each cleaning method when applied to the paint stratigraphy, so how to suitably combine different kinds of solvents, gelling systems and cleaning tools. Test 13 was carried out to investigate the high performance of rigid agar gels to incorporate into their mesh any particles dissolved, reducing any after treatment on the surface to remove the residues. The test has also verified that polysaccharide-based gel is able to control how the solvent is delivered and its solubility action during application. By using an emulsion water-in-oil, the advantage is that the two phases (water and benzyl alcohol) coexist but are distinct. This aspect is crucial in cleaning treatment to avoid an uncontrolled and non-selective action of a solvent mixture on paint materials. The final effect of Test 13 on the surface appears good in visible and UV light, but cross-section analysis shows that the thin shellac film under the ketone varnish has been partially altered (Figure 5). Due to its aromatic component and its polarity, benzyl alcohol can induce shellac and natural resin swellings, as observed in our test. Despite the effectiveness of the rigid gel, the high degree of retention and the medium volatility of the solvent may not be suitable for the underlying paint layer's safety. In the case of PVA-borax gel-based tests (T9; T12), it is difficult to control the gradual release of the solvent loaded, although the gel shows a high ability to adapt to uneven surfaces. The fast dispersion of polar solvent on the mock-up causes varnish marks and bleaching surface, especially along the edge of the gel application. By adding a paper layer between the painting surface and the gel, the effect is more even and satisfactory but not sufficiently controllable. However, the nanostructured gel-based series shows good performances in dissolving the thin layer of varnish without affecting the underlying pictorial materials. To assess their effective capacity to incorporate swollen paint materials when applied on the surface, Dry and Peggy gels were further evaluated under the same conditions, including the same solvent loaded and application times (Polar Coating B, application time of 3\({}^{\prime}\)). Results are shown in Figure 6. Through UV light imaging, it is possible to clearly identify that the Dry gels were significantly more effective in removing the softened ketone varnish compared to Peggy gels. Moreover, the advantage of these gels' transparency allows the monitoring of solvent action during application. These findings highlight the potential of these gels in applications requiring effective paint removal. Figure 5: Some steps of the cleaning test with benzyl alcohol loaded in agar gel: (**a**) application of the rigid gel on the surface by interposing a paper layer; (**b**) particles of the swollen varnish migrated into the agar mesh; (**c**) cross-section under UV light that shows the transition between a treated (on the left side of the dotted line) and an untreated area (on the right side). Numbers describe the layer stratigraphy: (1) paint layer; (2) natural resin film; (3) ketone-based varnish. The arrow highlights the edge between the treated and the untreated areas. In general, all tests involving nanostructured gels on the samples yielded satisfactory results by visual control. However, a comparison of the cross sections from Test 8 and Test 14 reveals a notable difference in outcomes (Figure 7). In Test 8, it appears that the solvent was absorbed to such an extent that it led to the alteration of the underlying shellac layer. This indicates that the cleaning method might have affected not only the varnish film but also the integrity of the layers beneath it. In contrast, Test 14 exhibited highly satisfactory results. The paint was effectively thinned without causing damage to the underlying paint layers.