## 3 Results  
Before the phasor lifetime analysis, fluorescence spectra of the individual materials were acquired using the same excitation wavelength used for FL measurements. The fluorescence bands of all spectra (Figure 1a) fell in the spectral range 450-650 nm, thus ensuring the suitability of the detection filter (510 \(\pm\) 42 nm; light blue rectangle in Figure 1a) used to collect the FL signal. The shape and the central wavelength (\(\approx\)525-540 nm) of the emission bands are in accordance with what can be found in the literature for these materials [5; 35]. Raman analysis of the pure materials (Figure 1b,c) confirms the chemical composition of the probed materials, revealing the main peaks associated with them (see Table 1). The binding materials belonged to three different groups: drying oil (linesed oil), natural wax (beeswax), and triterpen resin (mastic). In the Raman range analyzed, the spectra showed a background that varied according to the material. For mastic resin and beeswax, a stronger background competing with the characteristic Raman signals was observed. In the linseed oil, the background was lower and, therefore, the peaks were better resolved. The most intense peak in linseed oil (dried for 48 h, at room conditions) was at 1658 cm\({}^{-1}\), associated with the stretching vibration of a cis dialkyl C=C double bond in linoleic acid [36; 37]. As to the mastic resin, the main Raman signals were revealed at 1441 cm\({}^{-1}\)--with a shoulder at 1461 cm\({}^{-1}\)--and 1652 cm\({}^{-1}\), corresponding to \(\delta\)(CH\({}_{2}\)),v(CH\({}_{2}\)), and v(C=C), respectively [38; 39; 40; 41]. No bands associated with C=C vibrations were detected in the Raman spectrum of beeswax. The characteristic Raman bands at 1131 v\({}_{\text{as}}\)(C-C), 1172 v(C-C), and 1419 \(\delta\)(CH\({}_{3}\)) [36; 41] allowed the differentiation of beeswax from the other two binding materials. Regarding the pigments, the Raman spectrum of the red pigment clearly shows the characteristic peaks of iron oxide at 225 cm\({}^{-1}\), 293 cm\({}^{-1}\), 410 cm\({}^{-1}\), 497 cm\({}^{-1}\), 611 cm\({}^{-1}\), 1317 cm\({}^{-1}\), assigned to v\({}_{\text{s}}\)(Fe-O), \(\delta_{\text{s}}\)(Fe-O), and v\({}_{\text{as}}\)(Fe-OH) [42; 43]. An additional peak at 659 cm\({}^{-1}\) may belong to iron impurity in the form of magnetite, or to a disorder band in the crystalline structure of hematite, caused by exposure to a high temperature during burning [44; 45]. On the other hand, the lampblack pigment is characterized by the two broad bands of amorphous carbon--at 1315 cm\({}^{-1}\) and 1591 cm\({}^{-1}\)--assigned to the D- and G-bands of CC, respectively [46; 47]. FL measurements were performed on each sample using both single-point and imaging modes. Data were processed using the phasor method and, for all measurements, the \(\tau\)-phase was calculated as an average over 3000 acquisition points with 20 ms integration time each in the imaging mode, and 20 points with 15 s integration time for each decay in the single-point mode. The uncertainty for each \(\tau\)-phase value (reported in brackets in Table 1) is given by the maximum value between the standard deviation of the mean and the HWHM of the instrument response function (IRF) of 0.1 ns, measured as instrumental response to a laser pulse. Comparison of data provided by the two acquisition modalities showed that for most samples the imaging mode provides a more dispersed distribution of values than the single-point acquisition over the same region. A representative example is the linseed oil (LO) sample shown in Figure 2. The FL map (Figure 2b) is described by the color-scale distribution of \(g\) and \(s\) values in the phasor plot (Figure 2d), reported together with the values obtained via the single-point measurements (black circles in the diagram). The color scale of the density map corresponds to the number of decays with the same \(g\) and \(s\) values.