Diving into colours: A multi-analytical approach to a 16th century drawing by Gherardo Cibo

This paper gives account the first physical-chemical investigation of a drawing by Gherardo Cibo, one of the most autonomous and original Italian artists of the 16th century. A dilettante botanist, chemist, and draughtsman, Cibo developed the new visual practice of colour landscape drawing and left a series of notes devoted colour making theory and practices. In this study, one of Cibo's most refined coloured landscapes on paper was analysed with a multi-technique approach involving several non-destructive analyses, such as preliminary macroscopic and microscopic observations, X-ray fluorescence (XRF), mu-Raman, and mu-Fourier Transform Infrared (FTIR) spectroscopies. The analysis evidenced the presence of a preparatory layer made of lead white and a colour palette composed of both inorganic and natural organic pigments. Anglesite was identified in different colours, suggesting a generalized alteration process of the artwork associated to lead pigments, while the identification of lead chromate in some of the brown shades can be interpreted as a later retouching. Finally, some organic compounds were identified: Arabic gum, connected to the iron gall ink; collagen, probably adopted as a binder for some pigments; a fatty acid substance, possibly a wax; and a paint varnish mastic, most likely a surface finishing/pigment fixing or a late preservation treatment/retouching. These results, combined with historical and artistic information, allow a new understanding of the artist's drawing practices and techniques.