# Analytical Evaluation of Laser Cleaning Effectiveness in the Context of Contemporary Muralism
## 3 Results
### Empirical Evaluation  
During the cleaning process, five parameters were identified to evaluate the effectiveness and safety of laser cleaning on different samples, allowing the construction of radar charts for direct assessment [31]. Each criterion is assessed by the same author who prepared all the samples and assisted in the cleaning process. The author assigns a score ranging from 1 to 9 for each criterion; a higher score indicates better performance. The five parameters are as follows:  
* Presence of residues, i.e., the presence of uncleaned residues assessed with the naked eye during the cleaning procedure and under an optical microscope;
* Roughness of the surface (topography integrity), i.e., the conservation state of the cleaned surface evaluated using grazing light photography;
* Color change, evaluated by the naked eye, comparing color changes before and after cleaning, and then further verified by colorimetric measurements;
* Cleaning effectiveness, i.e., the minimum cleaning cycles needed to achieve an acceptable result;
* Pigment pickup, assessed as the color of the bottom layer of paint absorbed onto the quartz fiber membrane during the cleaning process. This material is then analyzed by Py-GC/MS in a second stage.  
The first three criteria aim to evaluate the aesthetic appearance of the mock-up after each cleaning process, while the last two are intended to identify whether the cleaning process causes severe damage to the bottom layer. The empirical evaluation scale is established as follows: For the presence of residue, scores range from nine, indicating no visible residue, to one, indicating over 90% residue. Surface roughness is scored from nine if the surface remains unchanged after cleaning to one if the engraving reaches the substrate (mortar basement). Color change is evaluated with a score of nine if the color remains the same after cleaning, and one if the color is completely altered. Cleaning effectiveness is based on the number of cycles required, with a score of nine for one cycle, six for two cycles, and three for three cycles. Pigment pickup is scored nine if there is no trace of the bottom layer color on the quartz tissue, and one if the bottom layer color is highly saturated. All the empirical scores are listed in Table 5.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  
The total score was found to depend significantly on the binder type of the painting material. Samples containing a styrene-acrylic binder (StyY) generally received a lower overall valuation, while samples with a fluorescent blue layer (AcrFB) achieved higher total scores. The comparison between samples AcrY-AcrFB and StyY-AcrB, representing the highest and lowest global evaluations, respectively, is detailed in Table 6.  
Table 6 shows that within the same sample, the radar charts for QS and LQS laser instruments showed similar cleaning effects under both fresh and aged conditions. For example, the chart for sample AcrY-AcrFB exhibited a balanced result, with high scores for all five criteria. In contrast, the shape of the chart for sample StyY-AcrB was flatter, indicating significantly lower scores for parameters such as \"color\", \"residue\", and \"effectiveness\". Combining the results of all samples, as shown in the complete set of charts reported in the Supplementary Materials, it was observed that these are the three parameters that contributed the most to the evaluation of satisfaction with the cleaning process.