## 3 Results and Discussion
### Case Study 1: Paintings
#### 3.1.2 Multispectral Imaging Investigations  
Figure 4 compares the IRR and UVF images of Painting 1 and Painting 2. The IRR investigation did not reveal any traces of _penttimenti_, carbonaceous underdrawings, or underlying pictorial brushstrokes corresponding with the original area of the paintings, nor traces of the original frame or tensioning. This last aspect further confirms that the fragments were extracted from large artworks and that they were not close to the original frame.  
In the case of Painting 1 (Figure 4A-C), the results suggest the presence of superficial retouching or pictorial integrations identifiable as dark grey in the IR images and as darker areas in the spectral response of the protective varnish under UV.  
The dark areas did not show any UVF, highlighting the extensive areas of reconstruction (in the upper and lower bands) and the retouching of certain details (in the original portion of the work). Ultraviolet fluorescence observation made it possible to differentiate the original portion of the _putto_'s face, which was of a higher quality than the part of the face attributable to subsequent restoration procedures.  
The bright whitish fluorescence response of the flesh tones and clouds, limited to the original portions, is typically attributable to lead white in oil medium [27], the identification of which was confirmed by the chemical analysis reported below. In addition, in the IR  
Figure 4: Photograph of Painting 1 and Painting 2 (**A,D**) and related 950 nm IR (**B,E**) and UV (**C,F**) images. In the IR images, the areas affected by repainting appear to be of a darker grey tone than the original pictorial layer of the same color in the visible range. The same pictorial areas appear devoid of visible fluorescence under a UV source (dark areas), confirming the mapping of pictorial retouchings overlapped onto the original surfaces.  
range, the perimeter of the original portion of the painting was visible in the central part of the current support.  
The upper and lower areas showed a different IR spectral response. In particular, greater IR absorption was observed, detectable by the darker shade of grey in the reflectographic image. This suggests that those areas indicate a remake, partially superimposed on the original painted area due to the resizing of the initial fragment [28].  
In Painting 2, the greater IR absorption (darker areas) suggests pictorial retouching of the original painting.  
Pictorial brushstrokes and remakes prevail in the brown background. This was probably necessary to harmonize the original area to the new support, both aesthetically and dimensionally. Indeed, the original pictorial surfaces are characterized by lower absorption in IR compared with the repainted area, the tones of which have darker gray tones than the original layers.  
Moreover, in the case of Painting 2, the images obtained by UVF (Figure 4D,E) highlight the presence of a surface layer of protective paint characterized by a bluish response (typical of an aged synthetic paint). This varnished layer makes it less possible to observe the behavior under UV of the underlying pictorial layer. Small differences are observable between the varnish applied to the original pictorial layer (limited to figurative subjects) and the brown remade layer (in the lower and upper bands of the painting).  
In the lower portion, the absence of fluorescence is observable, corresponding with an area that lacks the original support and it is of interest also because of the integration of the preparation layer (see the back of canvas support in Figure 1). The perimeter of this area corresponds with the anomaly observable on the back of the support.  
In both paintings, although the IR images indicate clearly the presence of a thick layer of altered protective varnish, it was possible to obtain a better reading of the illustrations and painted figures.