Giotto Unveiled: New Developments in Imaging and Elemental Analysis Techniques for Cultural Heritage

The Giotto’s masterpiece God the Father with Angels, never investigated till now, was studied by our team of local researchers, involved in application of scientific methods for cultural heritage since many years. Exploiting the integration of different knowledges, technologies and resources of our team, we were able to provide data to understand the painting technique, the pigment used and the underdrawing of this Giotto’s painting. We performed the following non-invasive analyses: Macro-XRF scanning (MA-XRF), Fiber optic reflectance spectroscopy (FORS), high resolution IR scanning reflectography, infrared false color (IRFC). Only portable instrumentations were used, with operating times compatible with the opening hours of exhibition. In particular, the analytical campaign was the opportunity to test the portable IR scanning prototype based on a peculiar spherical scanning system characterized by light weight and low cost motorized head. The analytical results revealed a painting technique already used by Giotto and based on different superimposed pigment layers. By combining the effectiveness of scanning portable-XRF (pXRF) with the responsive of image spectroscopic analysis, we move step by step toward the discovery of Giotto’s palette, with particular attention to the flesh tones in God the Father with Angels. The imaging data support the hypothesis of a detailed underlying sketch that includes also a drawing characterized by larger brush signs; the use of patrones for the face of “God” was supposed thanks to comparison with other Giotto masterpieces.