## 3 Results
### Edxr  
The analyses performed using portable EDXRF spectroscopy on the original banknote by [PERSON] revealed a characteristic elemental composition about both the banknote substrate and the artist's chromatic palette (Table 4). A common matrix was detected across all analysed areas, primarily composed of titanium (Ti), silicon (Si), and iron (Fe), corresponding to metal associated with paper fibers and printing inks. In several locations, additional elements such as copper (Cu) and gold (Au) were detected, typical markers of integrated metallic security threads and watermark features embedded in the banknote's structure. The most distinctive chemical signal differentiating the painted areas from the unaltered substrate was an increase in silicon content. The areas painted with Posa acrylic markers showed significantly elevated silicon levels compared to the banknote surface, where silicon was present only in trace amounts. This difference is consistent with the formulation of many commercial acrylic markers, which include silica-based additives to \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Before**} & \multirow{2}{*}{**SD**} & \multicolumn{2}{c}{**After Ageing**} & \multirow{2}{*}{**SD**} \\  & & **Ageing (\(\upmu\)m)** & & & **(\(\upmu\)m)** \\ \hline Banknote used by & & & & \\ RichardHTT & coating & 935 & 102 & & \\ \hline Banknote used in & & & & \\ experimentation & No coating & 924 & 105 & & \\ \hline RichardHTT pictorial layer & No coating & 120 & 62 & & \\ \hline Banknote + red POSCA & & 1065 & 112 & 1062 & 115 \\  & with CS coating & 1770 & 60 & 1690 & 90 \\ \hline Banknote + blue POSCA & & 1023 & 116 & 1025 & 118 \\  & with CS/CNC3 coating & 2010 & 90 & 1940 & 120 \\ \hline Banknote + yellow POSCA & & 1061 & 122 & 1060 & 125 \\  & with CS/CNC6 coating & 2250 & 150 & 2200 & 190 \\ \hline Banknote + green POSCA & & 1099 & 118 & 1102 & 120 \\  & with CS/CNC1.5 coating & 2240 & 70 & 2010 & 110 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Thickness measurements before and after artificial ageing. enhance pigment dispersion, opacity, and film durability. In contrast, aluminium (Al), a major component of the substrate, was significantly reduced or undetected in the painted zones. The EDXRF analysis of the chromatic areas in the laboratory-prepared banknote confirmed elemental compositional consistency with the base substrate but also highlighted specific markers of the applied materials (Table 5). Elemental analysis on several colour applications--black, red, light blue, blue, white, yellow, green, and pink--revealed moderate variations in their elemental amount. Silicon (Si), titanium (Ti), and iron (Fe) were the most recurrent elements, with variable yet systematic presence across the spectrum. Trace elements including zinc (Zn) and copper (Cu) were occasionally detected, reflecting either impurities or additives. Notably, there was an absence of transition metals commonly associated with inorganic pigments, supporting the conclusion that the UniPosca markers used in the experimental setup rely on organic pigments/colourants rather than traditional mineral-based formulations. The general homogeneity in metal content across the various colours, along with the prevalence of light elements and silicon enrichment, aligns with findings from previous studies on modern water-based markers and acrylic paints reported in the bibliography [18; 19; 69; 70].