## 3 Results  
### Commercial Sprays  
The identification of Raman spectra is complex due to the large number of bands, the small differences between different compounds of a similar nature, and problems with obtaining quality spectra. Despite this, it was possible to identify the main pigments of all the commercial sprays by means of Raman spectroscopy, and even some of the bands related to the binders. Moreover, the elemental analysis, which is not so often used in spray characterizations, provided relevant information to better understand their composition. The results of the XRF analysis of the commercial sprays are collected in Table 1, and molecular information and the spectra obtained by Raman spectroscopy are collected in Table 2 and Figures 2-4. As can be seen in Table 1, most of the commercial sprays had titanium as a major element. This was usually present as titanium oxide in rutile form, a common compound used in sprays as an extenders and opacifier of paints [7,8]. However, it was evident that this pattern is not present in the \"Decor\" brand, in which titanium was not a major element. In fact, in general, in this brand the elemental composition of the spray was more complex. This could be related to the quality of the sprays, since the \"Titan\" and \"Montana\" are sprays generally used in street art [6]. Considering the above, the number of major elements was lower, which could indicate: (1) a simpler composition of the mixture; or (2) the use of organic compounds that cannot be analysed by XRF were used in conjunction with rutile as an additive. However, regarding the molecular analysis, it was striking that the identification of rutile [16], despite being the major component in many sprays, was only identified when it was used as pigment as in the case of \"White 566\" and \"Light Grey ZT113\", and in a pigment mixture in \"Arctic Blue\", in which the rutile was mixed with the PB15 phthalocyanine blue [15]. Another remarkable element observed in the XRF analysis was iron, present mostly in sprays of the red and yellow palette, and especially in the brown colours \"Druid Brown RV-246\" and \"Light Brown ZT120\". In these sprays, Raman spectroscopy revealed a mixture ofiron oxidem, hematite, and iron hydroxide, goethite [16]. Finally, the presence of copper was also significant due to its presence as major element in the \"Dark Blue RV-5005\" spray, which could indicate the use of a pigment based on this element that is usual in blue colours [19]. As was presumable by the elemental analysis results, the pigment PB15, a copper phthalocyanine, was identified by Raman spectroscopy [15]. Figure 3: Raman spectra of the commercial sprays of the Montana brand. Figure 2: Raman spectra of the commercial sprays of the Titan brand. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Brand** & **Pigment** & **Major Elements** & **Minor Elements** \\ \hline \multirow{4}{*}{Titan} & Orange (554) & Ti, Fe, Cl & Zn, Pb, Co, Zr, Ca \\ \cline{2-4}  & White (566) & Ti & – \\ \cline{2-4}  & Yellow (529) & Ti, Fe & Ca, Zr, Co, Cl, Zn \\ \hline \multirow{4}{*}{Montana} & Vivid Red (RV-3001) & Ti, Fe & Ca, Co, Zr, Zn \\ \cline{2-4}  & Artic Blue (RV-29) & Ti & – \\ \cline{2-4}  & Dark Blue (RV-5005) & Ti, Cu & Si, Ca, Fe \\ \cline{2-4}  & Druid Brown (RV-246) & Ti, Fe & Zr \\ \cline{2-4}  & Cologno N. Green (RV-237) & Ti, Fe & Cl, Ca, Cu, Si, Zr, Co \\ \hline \multirow{4}{*}{Decor Pintura} & Medium Yellow (ZT107) & Bi, V & Zr, Co, Zn, Ca, Ti, Cl \\ \cline{2-4}  & Light Grey (ZT113) & Ti & Fe, Si, Zr, Ca \\ \cline{2-4}  & May Green (ZT129) & Cl, Cu, Zr, Ca & Ti, Fe, Co \\ \cline{2-4}  & Light Brown (ZT120) & Fe & Zr, Si, Zn, Ca, Co \\ \cline{2-4}  & Violet (ZT131) & Ti, Fe, Zr & Ca, Co, Zn \\ \cline{2-4}  & Fuchsia (ZT134) & Ti & Fe, Zr, Cl, Co, Ca, Cr \\ \cline{2-4}  & Bordeaux (ZT148) & Cl, Fe, Ca, Si, Zr & Co, Ti, Zn \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Elements identified in the commercial sprays. The major elements were considered up to 10% of relative presence.