Complementary MA‐XRF and μ‐Raman results on two Leonardo da Vinci drawings

In 2018 all of Leonardo's drawings and manuscripts belonging to the Biblioteca Reale di Torino were moved to ICRCPAL for a complete scientific characterisation in preparation for the celebrations of the 500th anniversary of the artist's death. Except for the famous Autoritratto that was already studied twice in this manner (2012, 2015), the other drawings and documents had never been subjected to scientific investigations. This paper reports the results of the non-destructive analysis of two drawings: Studi di gambe virili and Autoritratto. The use of three complementary techniques, namely macro-X Ray Fluorescence (MA-XRF), μ-Raman spectroscopy and Atomic Force Microscopy (AFM), that have different penetration into the material, allowed for the complete chemical characterisation of the artworks. The analyses evidenced the artist's versatility and his mastery in the use of metal points, even unusual ones, such as the pure copper-point described in literature but never previously revealed in Leonardo's drawings and, to the knowledge of the authors, also in other artists of the 15th century. MA-XRF also showed the presence of pentimenti in the Studi di gambe virili and highlighted that the Autoritratto was drawn without a metal point preparatory sketch. AFM topographies also revealed that the Autoritratto urgently requires chemical stabilisation. The data collected underline the need to reconsider and reassess the historic-artistic descriptions of the drawings and that further investigation of other works by Leonardo is necessary to obtain more information supported by scientific studies on the artist's techniques and materials.