Study of materials and techniques in painted ceiling panels from a palace in Cremona (Italy, 15th century)

Background: This study concerns the analysis of four painted wooden panels from the second half of the 15th century which embellish the ceiling of a palace situated in Cremona (Northern Italy). This type of painting was generally used to decorate the top of the walls and the ceilings of the rooms in aristocratic palaces and they usually portray the owner’s ancestors, family members or important visitors. The paintings are of historical importance since they enable us to study the clothing and hair styles which were in fashionable in Italy during the Renaissance. These panels were heavily damaged and required a lot of restoration including the cleaning of the paint layers. This enabled us to carry out a thorough examination of the materials and techniques used for creating these paintings. Results: Various micro-samples were taken in order to distinguish the materials and, in particular: (i) to analyze the ground layer and study its function; (ii) to typify the organic binders and the pigments of the polychrome films. The stratigraphic sequence of micro-samples was analyzed using optical microscopy, the elemental composition was determined by means of the SEM-EDX technique while the organic binders were analyzed by means of μFT-IR spectroscopy. The main component of ground layer proved to be clay. The organic binder was probably composed of a protein-based material such as animal glue. This type of ground layer is similar to the traditional 15th century Flemish formula and seems to confirm the strong influence of that artistic technique in Northern Italy. Cross-section investigation showed a primer layer over the ground layer made of white lead pigment. In fact, a white primer was used to cover the ground layer of yellowish clay common in Central Europe. The importance of this research is also confirmed by the study of paint films, for which pigments such as azurite or cinnabar were used. Red lake pigment for painting the subjects’ complexions was emphasized. Conclusions: The analyses provide new detailed information concerning the materials used for painting the ceiling panels, the layer sequence of the paints and Northern Italian 15th century painting techniques.