## 2 Materials and Methods  
### Samples  
Some of the materials typically used as binders and coatings in artworks--specifically, linseed oil (LO), mastic (M) (a triterpen resin) [10], and beeswax (BW)--were selected for the combined FL-Raman spectroscopy analysis. The materials were examined either in pure form or mixed with red iron oxide (IO) pigment or lampblack (LB) (a carbon-based pigment historically obtained from the soot of oil lamps [31]). The mixture with the pigment was intended to reproduce a simplified version of the patinas that were applied in the past on the surface of the artefacts for aesthetic and/or protective functions [32]. The material layers were spread on glass or on metallic support (bronze (B)) in order to evaluate the influence of the substrate on fluorescence intensity, FL lifetime, and Raman spectra. The complete list of samples with their description can be found in Table 1.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Samples Description**} & \multirow{2}{*}{**Acronym**} & \multicolumn{2}{c}{**Mean \(\tau\)-phase [ns]**} & \multirow{2}{*}{**Principal Raman Signals [cm\({}^{-1}\)]**} \\  & & & & 727w, 866m, 972w, 1024w, 1078m, 1268 ms, \\ \hline \multirow{2}{*}{Linseed oil} & LO & 2.44 (0.10) & 1302 ms, 1444s, 1658w, 2727w, 2885m, \\  & & & 2932w, 3017w \\ \hline \multirow{2}{*}{Mastic} & M & 2.26 (0.10) & 468w, 533w, 596m, 722m, 937m, 1200m, 127w, 1315w, 1441 ms, 1461 sh, 1653 ms, 1698h, 2884 sh, 2926m \\  & & & 1698h, 288 th, 2926m \\ \hline \multirow{2}{*}{Beeswax} & BW & 2.11 (0.10) & 889w, 1063s, 1131s, 1172w, 1296s, 1419m, 1441s, 1464m, 2726w, 2850m, 2929 sh \\  & & & 146w, 225s, 293 vs, 410s, 497m, 611 ms, 659 br, 1317 br \\ \hline \multirow{2}{*}{Lampblack} & LB & 3.28 (0.12) & 1315s,br; 1591s,br \\  & & & 225s, 293 vs, 411s, 498m, 612 ms, \\ \hline \multirow{2}{*}{Beeswax + iron oxide on glass} & BW + IO & 2.90 (0.17) & 671 br, 1062m, 1131m, 1321 br, 1439m, 1464 br, 2848w, 2883w \\  & & & 147w, 226s, 293 vs, 412s, 498m, \\  & & & 612 ms, 662 br, 1320 br, 1448 br, 1656w,br \\ \hline \multirow{2}{*}{Linseed oil + iron oxide on glass} & LO + IO & 2.36 (0.10) & 227s, 294 vs, 413s, 495m, 611m, \\  & & & 866m,br, 1085m, 1303 ms, 1441 ms, 1662 br, 1733 br \\ \hline \multirow{2}{*}{Mastic + lampblack on glass} & BW + LB & 2.97 (0.16) & 1315s,br '1597s,br * \\  & & & 1314s,br '1, 1445 br, 1588s,br '2, 880 br,sh, \\  & & & 2935 br \\ \hline \multirow{2}{*}{Linseed oil + lampblack on glass} & LO + LB & 2.34 (0.10) & 872 br, 1087w, 1313s, 1441s, 1596s, \\  & & & 1732 sh, 1856m, 2910m, 2936m \\ \hline \multirow{2}{*}{Linseed oil on bronze} & LO(b) & 2.26 (0.10) & 1064w, 1080w, 1305m, 1439 ms, 1654 br, 1723 br \\  & & & 1723 br \\ \hline \multirow{2}{*}{Oleoresin (Linseed oil + mastic  on bronze)} & OR(b) & 1.43 (0.10) & 1063w, 1085w,1308m, 1444m, 1647 br, 2863 br, 2934 br \\  & & & 227s, 293s, 413m, 465w, 612m,br ', \\  & & & 10632, 1134w, 1175w, 1296m, 1442s, 1461 sh, 1653w,br, 2852m, 2883m, 2938 br \\ \hline \hline \end{tabular}  
* only for samples containing more than one component: Raman peaks attributable to a pigment  
\end{table}
Table 1: List of the analyzed samples with mean \(\tau\)-phase and main Raman peaks.