Colour - as an optical phenomenon - was and is of paramount importance to the art of Augusto Giacometti (1877-1947). This makes it even more worrying that the colours of many of his paintings, particularly those from the Florentine period, have drastically changed and continue to change.
The fact that degradation and discoloration processes of paint layers can lead to changes in colour tones has long been known in the field of art technology and cultural heritage analysis, but such processes are still not fully understood.
In a previous study, SIK-ISEA was able to obtain some initial information about the tube colours used in Giacometti's works showing discolouration and the possible causes of these changes. Investigations will continue as part of the research project launched in 2024, with a focus on lead-containing pigments, which appear to play a key role in the discolouration of the paint layers. The starting point for the project is the work ‘Farbkreis’ (Colour Wheel, c. 1907, oil paint on prepared canvas), the Colour Wheel that Giacometti used as a tool to compose with colours, where the phenomenon of discolouration is highly visible.