# Authentication of a Painting by [PERSON] Using Modern Multi-Analytical Methods
## 3 Results and Discussions
### Analysis of Painting Materials
The yellow pigment (Figure 17e) in addition to the binder peaks has the 724 and 812 cm\({}^{-1}\) peaks characteristic of _Lithopone_[10; 26; 27; 28; 31; 32; 33; 34; 36]. The white pigment (Figure 17f) shows the peaks 3429, 3388, 2936, 2860, 2227, 2055, 1730, 1640, 1618, 1458, 1400, 1276, 870, 812, 724, 626 cm\({}^{-1}\) characteristic of the binder and the white zinc [10; 26; 27; 28; 31; 32; 33; 34; 37]. For the varnish, pictorial materials and support samples, representative areas were selected in the SEM images (Figure 16), which, in conjunction with their elemental EDX analysis (Table 1), allowed the evaluation of archaeometric characteristics, such as the porosity gradient of the varnish, colors and preparation, the degree of penetration of the colors in the varnish and of the varnish/colors by the oxidatively fouled superficial structures, and the chemometric ones, respectively: elemental stoichiometry reports: Si/Al, C/O, C/S, S/O, Zn/O, Zn/C, and Zn/S (Table 3), which allowed the estimation of the period of the painting elaboration around 1890. The data in Table 3 show a good correlation between the two archaeometric characteristics highlighted in the W4 samples (250 \(\upmu\)m for the gradient of the porosity of the colors and varnish, respectively, the degree of penetration of the colors in the varnish and of the fouled structures from the surface in the volume phase for the white colors, 130-260 \(\upmu\)m to blue, 50-130 \(\upmu\)m to red and yellow) and W5 (150 \(\upmu\)m depth of penetration of oxidatively fouled superficial structures, to white; 50-130 \(\upmu\)m to blue, red, and yellow). The two archaeometric characteristics correspond to a range of about 130 years (in white the rate is about 1.0-2.0 \(\upmu\)m/year; in blue 0.2-2.0 \(\upmu\)m/year; in red and yellow 0.5-1.0 \(\upmu\)m/year; in varnish 0.2-0.5 \(\upmu\)m/year), considering the constant storage conditions. Regarding the chemometric characteristics (columns 1-7 of Table 3), the evaluation is based on the stoichiometric ratio of the basic congruent, from the composition of the pictorial materials, namely: Si/Al (the caustic modulus of the earth colors), which varies between 0.589 and 1.084; C/O (of CO\({}_{3}\)2- ion) is 0.25; S/O (of SO\({}_{4}\)2- ion) is 0.5 and Zn/O (of zinc white-ZnO) is 4.063. The seven chemometric characteristics of the colors in Table 3 represent the deviations from these four stoichiometric ratios, due to oxidative processes in superficial structures or dilution by exogenous contamination with aluminate, silicate, carbonate, and sulphate anions, which occur during display or storage without display. As for the C/S, Zn/C, and Zn/S ratios, only the first one, which corresponds to the ratio between carbonate and sulfate anions, has a wide range of variation, which allows to evaluate the degree of mixing between colors when elaborating (enacting), and the others provide information on the degree of carbonation and the degree of sulfation that occur over time. These represent reports resulting from oxidative processes and impurification processes with anions from acid-basic and complexation processes. The first definite chemometric characteristic related to the increase of the porosity due to the fragility of the binder and the penetration of CO\({}_{2}\), respectively, of SO\({}_{2}\) in the presence of hygroscopic humidity (sequential processes of carbonation and sulfation), are given by the C/S and Zn/C ratios. The C/S ratio increases compared with the reference sample (W2), for the white samples between 0.08 (W5) and 3.8 (W1) times; in the blue ones, between 2.26 (B2) and 78.4 (B4) times, in the red ones between 1.00 and 1.50 times, and for yellow 5.3 times. These values correspond to deviations for about 130 years old.