Short-wave infrared hyperspectral imaging for organic media classification and mapping in paintings: the case of Willi Baumeister

Hyperspectral imaging has become an increasingly valuable non-invasive technique in heritage science, particularly for the documentation and classification of pigments. However, the classification of organic binding media remains less explored. This study presents a workflow for the mapping of binding media using short-wave infrared hyperspectral imaging (1000–2500 nm), supported by a reference spectral library of pure binding media films. To assess the reliability of the hyperspectral imaging system, spectral data were compared with measurements obtained using a benchtop spectrophotometer. A tailored data pre-processing and classification pipeline was developed and applied to two paintings by the German modernist Willi Baumeister. The results demonstrate successful spatial mapping of linseed oil and cellulose nitrate. This research underscores both the capabilities and limitations of short-wave infrared hyperspectral imaging as a non-invasive screening method to inform targeted sampling strategies. At the same time, it complements existing knowledge and contributes to a deeper understanding of the artist’s working methods.