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This paper presents the results of a comprehensive diagnostic investigation carried out on five paintings (three wood panels and two paintings on canvas) by Lorenzo Lotto, one of the most significant artists of the Italian Renaissance in the first half of 16th century. The paintings considered belong to 1508-1522 period, corresponding to the most significant years of Lotto's evolution. A wide array of non-invasive (reflectance spectrometry and X-ray fluorescence) and micro-invasive analytical techniques (optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, micro-FTIR spectroscopy, micro-Raman spectroscopy, gas chromatography coupled with mass spectrometry and high performance liquid chromatography coupled with photodiode array detection and mass spectrometry) were applied in order to provide a large set of significant data, limiting as much as possible the sampling. This study has proved that Lotto's painting palette was typical of Venetian practice of that period, but some significant peculiarities emerged: the use of two kinds of red lakes, the addition of calcium carbonate and colourless powdered glass, the latter frequently found in pictorial and ground layers. Moreover, the integrated investigation showed that Lotto's technique was sometimes characterized by the use of coloured priming and multi-layer sequences with complex mixtures. Chromatographic analyses allowed to identify in all specimens: azelaic, palmitic and stearic acids, generally referring to the presence of drying oils. The extension of additional non-invasive examination to about 50 paintings by the same author, spanning from 1505 to around 1556, helped to verify the evolution in the use of some pigments, such as the yellow ones, where Pb-Sb yellow was used alongside Pb-Sn yellow.

During the last restoration (2008–2011) of the polychrome terracotta altarpiece called Coronation of Virgin between Saints Rocco, Sebastian, Peter martyr and Antonio abbot, located in the collegiate church of S. Maria Assunta in Montecassiano (Macerata, Italy), scientific investigations were carried out to acquire detailed information about the painting technique. The identification of materials allowed a correct restoration.\ud The altarpiece is almost entirely realized by Marco della Robbia (Fra Mattia), dates back to the first half of the XVI century and represents an interesting example of painted ter- racotta produced by using two different techniques: glazed polychrome terracotta and the “cold painting” technique.\ud The characterization of the samples’ material constituents was obtained by analysing the cross-sections and the frag- ments by different techniques (optical, SEM-EDS and ATR- FTIR microscopy as well as GC-MS), as the real nature of a component is often difficult to assess with one single tech- nique.\ud The optical microscope examination of paint cross- sections shows the presence of many layers, indicating the complexity of the paint stratigraphic morphologies. The original polychromy of della Robbia’s masterpiece is con- stituted of cinnabar, red lake, red lead, orpiment, red ochre, lead white, lead tin yellow, green earth and raw umber. Two different types of gilding technique have been distinguished. The first one presents a glue mordant, and the second one shows an oil mordant composed by a mixture of red lead, red ochre, cinnabar and orpiment. The GC-MS analysis al- lowed the characterisation of linseed oil and a mixture of an- imal glue and egg as binding media stratigraphically located by the use of ATR-FTIR mapping microscopy. The analyti- cal results of the painted terracotta integrated investigations show that original technique adopted is characterised by the application of pigments in an oil-binding medium directly applied on the substrates, probably treated with oil and ani- mal glue.\ud A large number of overpaintings above the original scheme of polychromy was found, which could be ascribed to almost three different interventions; the absence of mod- ern pigments suggests that they could be realized long ago

Dissemination of Della Robbia glazed terracotta in the Marche (Italy) region started from the third decade of the 16th century. Numerous altarpieces, some of which no longer exist, document this artistic production. The protagonists of this diffusion phase were two of Andrea Della Robbia's sons, Marco (Fra Mattia) and Francesco (Fra Ambrogio).\ud This paper shows the results of the scientific investigations carried out on constitutive materials of different altarpieces located in South Marche belonging to the Fra Mattia's production: the Coronation of Virgin between Saints Rocco, Sebastian, Peter martyr and Antonio abbot, dated back to 1527-30, located in the collegiate church of S. Maria Assunta in Montecassiano; the Annunciation, dated back to 1520, placed in the church of S. Maria del Soccorso in Arcevia; the fragmentary Crowned Madonna and saints altarpiece, probably realized after 1531, today preserved in Civic Museum of Ripatransone.\ud The first altarpiece was made in Montecassiano using two different assembling or production techniques: the external part of the lunette and the pillar strips are made of glazed polychrome terracotta, while the altar step and the internal part are an interesting and uncommon example of polychrome painted terracotta. The provenance of the glazed Arcevia altarpiece is not clear yet: some historians hypothesize a local manufacture of Fra Mattia and some others a Roman or Florentine production. The remaining parts of Ripatransone altarpiece are partially glazed and partially not coated perhaps because they were unfinished and not yet painted.\ud Clay body samples collected from the above mentioned altarpieces were investigated using different analytical techniques (OM, XRD, XRF, PIXE) to point out differences in chemical and mineralogical composition and to determine if the altarpieces were made by using local raw clay materials or other clays from Tuscany or Campania as in the Della Robbia previous production. A comparison has also been made with literature data on the Della Robbia terracotta masterpieces.\u2028From the chemical point of view, the clay bodies show a good compositional homogeneity and result calcium and iron-rich according with the raw local materials. The presence of gehlenite, pyroxenes, and hematite and the incomplete decomposition of clay minerals indicate that firing for all different terracotta parts occurred in a thermal range between 800 and 950° C, mostly in oxidizing conditions