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Here, the X‐ray fluorescence technique is used to determine the thickness of a coating layer as well as to analyze the surface of objects. Four metals (Ag, Cu, Fe, Pb) were covered with increasing thicknesses of gold. The measurements were performed with a commercial handheld instrument, X‐SORT (Spectro). In double layers, the thickness of the covering layer was assessed by (a) the ratio between the most intense fluorescence lines of the covered element, (b) a cross‐ratio between two lines of the elements in the two layers, and (c) the ordinary partial least squares (PLS) regression method. In all cases, the curves obtained could be used for the quantitative determination of the thickness. The experimental data followed the theoretical trend even though the values of the attenuation parameters were not always in agreement with the theoretical ones. Comparisons and discussion of the results of the different approaches and also with models in the literature are made. The methods studied were applied to determine the nature of the coating layers of some gilded objects and proved to be suitable for estimating the thickness of gold by providing results that were in good agreement with each other.

Two paintings by the Neapolitan Renaissance painter Colantonio were studied with two non-invasive techniques to enrich the technical–scientific documentation. Infrared reflectography (IR) and x-ray fluorescence (XRF) analyses were performed on Saint Jerome in the studio and Saint Francis delivering the Rule, paintings preserved in the Museo e Real Bosco di Capodimonte. The IR scanning was performed to look beyond the visible layers of the paint for the preparatory drawings and pentimenti, or changes made during the painting process. The XRF technique was applied in many points to determine the elemental composition and enable the identification of pigments and materials used in paint and in the preparatory layers. Elemental XRF mapping was also carried out on a region of particular interest. Results provide an initial overview and hypothesis of color palette and techniques used by the artist.

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Diagnostic analyses on a contemporary painting on canvas were performed with X-ray fluorescence (XRF), multispectral imaging and scanning electron microscope/energy dispersive spectroscopy (SEM/EDS). The results of each method provided complementary information to deepen the knowledge of the pictorial technique. Multispectral imaging provided insight into the topmost layers. XRF analysis made it possible to characterize the chemical composition of some materials and pigments used by the artist. Additional information such as that relating to canvas preparation emerged with the SEM/EDS technique. The results reveal (i) the use of pre-treated industrial canvas; (ii) the preparatory layer consists of plaster covered with a primer with titanium white, zinc and lithopone; (iii) a layer of cadmium yellow ground was inserted to give depth and three-dimensionality to the painting; (iv) the absence of underlying design; (v) the characterized pigments are all contemporary and (vi) a fixative spray covers the paint.