The painting technique of Konrad Witz: An example of experimentation with innovative materials in 15th century

Konrad Witz represents an artist of great interest having worked in a period (first half of 15th century) of experimentation of materials, in the field of painting. The four paintings on wooden panels, kept at the Musée d'Art et d'Histoire in Genève (Switzerland), are a clear example of the artist’s will to pay attention to detail, to the brilliance of colours and to shades. A multi-analytical approach was applied in order to obtain information about materials, the technique used by the artist and the state of conservation of the four paintings, with the perspective of a restoration work. This purpose was achieved thanks to the application of non-invasive techniques, i.e. in situ X-ray fluorescence (XRF) through portable instrument, and micro sampling for Scanning Electron Microscopy coupled to microanalysis (SEM-EDS), micro Fourier Transform Infrared Spectroscopy (FTIR) and Gas-Chromatography coupled to Mass Spectrometry (GC–MS) analyses. Results showed the presence of a mixed technique “grease tempera” and the artist’s research in the use of innovative materials and technique for that period, i.e. the presence of small glassy violet particles inside a red lacquer layer, made of silicon, aluminium, potassium, sodium and manganese, as revealed by XRF and SEM-EDS analyses