# Materials and Technique: The First Look at [PERSON]
## 3 Results and Discussion  
### Material Mapping, Retouching, and Remaking  
The UV fluorescence photography led to a preliminary mapping of the surfaces, which differentiated between the use of organic and inorganic materials; these presented with a characteristic fluorescence. First, it was possible to identify the presence of a significant quantity of zinc white, a pigment in use since the late eighteenth century, and therefore, associated with areas affected by pictorial retouching [33]. Indeed, the presence of zinc (Zn) was also detected by X-Ray fluorescence (XRF) in the punctual analyses of the restored areas [2]. Zinc white pigment is clearly visible due to its lemon-yellow fluorescence in the lower part of panel A, representing the betrayal of [PERSON]. It is also visible under the window, which appears as a bright blue color in the image due to a paper which served to shield the apse from the outdoor sunlight (Figure 2) [34]. In the upper part of the same panel, especially in the background, a light yellow fluorescence is visible; this could be associated with the azurite binder, a pigment which has been recognized in the blue areas via spectroscopic analyses with XRF due to the clear presence of copper (Cu) [2]. This same fluorescence can also be observed in panel 4, the last from the left side of the apse conch, where the resurrection of [PERSON] is represented (see Figure 3A). Areas that appear white in visible light show a faint light blue fluorescence (Figure 3B); this may be associated with calcium carbonate white, contrary to the hypothesis of the art historians that assumed that it was the use of lead white, used in the highlights of the paintings. A detail was acquired in panel 4 wherein some fluorescent lines were observed in the general view of the wall (Figure 3A). The image in Figure 3B shows how the rays that emanate from the angels are characterized by a yellow-orange fluorescence which could be due to the presence of organic material. In accordance with art historians, the presence of possible original gilding work was hypothesized, and therefore, the organic substance whose fluorescence is observed could be referred to as the so-called _missing_, which was used to make the adhesive for the gold. Optical microscopy revealed the presence of golden traces in the rays (Figure 3C); indeed, the X Ray Fluorescence analyses, performed after the first round of image analyses, confirmed the theory that gilding had taken place. In fact, XRF spectroscopy detected the presence of gold (Au) as a chemical element that characterized those same areas [2]. The glue used for gilding was generally made of siccative oil and terpene resin; therefore, the yellow fluorescence may be associated with the lipidic component of the _missing_[35, 36, 37]. Infrared Reflectography, together with the Infrared False Colors, allowed us to distinguish between the portions of the painting that were affected by pictorial restorations. Pigments appearing similar in visible light may exhibit a different response to infrared radiation, which is rendered at a different level of brightness in reflectographic images; this difference results in a different color response in the false color infrared images. An example is shown in panel A, in Figure 4B, in which the restoration areas in the green land are identifiable as spots with lighter levels of gray, compared with the surrounding areas. This restoration intervention is also confirmed in false color images (Figure 4C), in which the same spots exhibit a pinkish color that may be attributable to the original materials, unlike those exhibiting a green color. Once again, via the false color images, it was possible to recognize small portions of paintings in which different materials were used. Compared with most areas, which appeared chromatically similar to the naked eye, as in the case of the blue near the Virgin's head in the scene of the deposition (Figure 5C), a single fragment shows a pink-red response in the false color image.