## 3 Results and Discussion
### Colorimetric Investigation
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{8}{c}{**Water in Agarose**} & \multicolumn{2}{c}{**Tween 20 in Agarose**} & \multicolumn{2}{c}{**Velvesil TM Plus**} \\ \hline \multirow{4}{*}{SSw} & \multicolumn{2}{c}{**L\({}^{*}\)**} & **a\({}^{*}\)** & **b\({}^{*}\)** & **L\({}^{*}\)** & **a\({}^{*}\)** & **b\({}^{*}\)** & **L\({}^{*}\)** & **a\({}^{*}\)** & **b\({}^{*}\)** \\ \cline{3-11}  & \multirow{4}{*}{t\({}_{0}\)} & 65.04 \(\pm\) & 2.22 \(\pm\) & 40.65 \(\pm\) & 61.54 \(\pm\) & 2.43 \(\pm\) & 41.70 \(\pm\) & 61.55 \(\pm\) & 3.14 \(\pm\) & 42.82 \(\pm\) \\  & 1.18 & 0.14 & 1.30 & 1.55 & 0.19 & 1.58 & 2.37 & 0.36 & 3.04 \\  & 62.48 \(\pm\) & 2.52 \(\pm\) & 37.37 \(\pm\) & 63.87 \(\pm\) & 2.62 \(\pm\) & 39.74 \(\pm\) & 64.20 \(\pm\) & 2.93 \(\pm\) & 38.94 \(\pm\) \\  & 0.65 & 0.12 & 0.17 & 0.25 & 0.16 & 0.79 & 0.25 & 0.07 & 0.24 \\  & 63.79 \(\pm\) & 2.60 \(\pm\) & 41.49 \(\pm\) & 63.52 \(\pm\) & 2.68 \(\pm\) & 40.56 \(\pm\) & 62.28 \(\pm\) & 3.05 \(\pm\) & 40.57 \(\pm\) \\  & 0.36 & 0.05 & 0.18 & 0.40 & 0.06 & 0.21 & 0.13 & 0.02 & 1.26 \\  & t\({}_{3}\) & 64.85 \(\pm\) & 2.45 \(\pm\) & 40.11 \(\pm\) & 64.64 \(\pm\) & 1.92 \(\pm\) & 40.84 \(\pm\) & 64.02 \(\pm\) & 2.99 \(\pm\) & 38.99 \(\pm\) \\  & 0.35 & 0.023 & 0.13 & 0.06 & 0.10 & 0.52 & 1.17 & 0.25 & 0.63 \\  & 65.40 \(\pm\) & 2.64 \(\pm\) & 39.67 \(\pm\) & 64.35 \(\pm\) & 2.46 \(\pm\) & 39.11 \(\pm\) & 64.79 \(\pm\) & 2.44 \(\pm\) & 38.69 \(\pm\) \\  & 0.43 & 0.04 & 0.46 & 0.97 & 0.17 & 0.34 & 1.02 & 0.20 & 0.05 \\  & 64.81 \(\pm\) & 1.56 \(\pm\) & 50.78 \(\pm\) & 65.15 \(\pm\) & 1.56 \(\pm\) & 58.32 \(\pm\) & 64.21 \(\pm\) & 2.99 \(\pm\) & 58.15 \(\pm\) \\  & 0.58 & 0.18 & 2.75 & 0.34 & 0.15 & 0.98 & 0.40 & 0.50 & 2.82 \\  & 61.44 \(\pm\) & 1.44 \(\pm\) & 48.70 \(\pm\) & 62.25 \(\pm\) & 1.60 \(\pm\) & 54.33 \(\pm\) & 64.40 \(\pm\) & 2.05 \(\pm\) & 49.80 \(\pm\) \\  & 0.06 & 0.15 & 0.93 & 0.29 & 0.16 & 1.04 & 0.20 & 0.06 & 0.95 \\  & 61.10 \(\pm\) & 1.64 \(\pm\) & 49.86 \(\pm\) & 61.80 \(\pm\) & 1.33 \(\pm\) & 54.01 \(\pm\) & 64.32 \(\pm\) & 2.12 \(\pm\) & 47.89 \(\pm\) \\  & 0.42 & 0.14 & 0.47 & 0.29 & 0.02 & 0.04 & 1.26 & 0.20 & 3.25 \\  & 61.86 \(\pm\) & 1.56 \(\pm\) & 48.61 \(\pm\) & 61.73 \(\pm\) & 1.23 \(\pm\) & 53.97 \(\pm\) & 63.78 \(\pm\) & 2.25 \(\pm\) & 45.55 \(\pm\) \\  & 0.40 & 0.10 & 0.93 & 0.22 & 0.12 & 0.56 & 0.60 & 0.02 & 0.46 \\  & 61.40 \(\pm\) & 1.72 \(\pm\) & 47.40 \(\pm\) & 62.64 \(\pm\) & 1.16 \(\pm\) & 52.29 \(\pm\) & 63.17 \(\pm\) & 2.77 \(\pm\) & 41.24 \(\pm\) \\  & 0.05 & 0.03 & 1.17 & 0.39 & 0.03 & 0.40 & 1.33 & 0.03 & 0.08 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Color coordinates L\({}^{*}\), a\({}^{*}\), and b\({}^{*}\) measured before (t\({}_{0}\)), and after the cleaning tests (t\({}_{1}\), t\({}_{2}\), t\({}_{3}\), and t\({}_{4}\)). 48.12% and 33.84% of the variance, respectively for the PC1 and the PC2) are displayed in Figure 2a. Similar behavior was observed for the \(\Delta\)PCs referred to in the Sw area, except for 30 min of exposure, where an increase of the \(\Delta\)PC was observed (Figure 2b). An accurate reading of the loadings (Figure 2c) allowed us to explain these results: \(\Delta\)PC1 behavior was mainly driven by the L* variability, whereas the \(\Delta\)PC2 was influenced by the a* and b* variability, with a higher influence by the latter. The hypothesis about the effect of the water in the agarose test was strengthened. In fact, \(\Delta\)PC1 and \(\Delta\)PC2 were characterized by a drop of around 60 min, related to L* and b*, confirming what was observed by \(\Delta\)E* trends. There were no cases demonstrating the water in agarose cleaning effect. Indeed, the blue and light blue lines (\(\Delta\)PC1 and \(\Delta\)PC2 of the water in agarose test) did not rise back and exceed the starting point of the soiled dark surface.