Nature and origin of black spots found on Miró paintings: a non-invasive study Original Research Article

The degradation mechanism of cadmium pigments in an oil painting by Joan Miró is determined and reproduced. All possible chemical reactions leading to the observed alteration are checked in laboratory conditions. The behaviour of the different materials (support, pigments and binding medium) are determined. The study of the reaction and products is made using optical microscopy, scanning electron microscopy (SEM) with an energy dispersive X-ray detector, Fourier transform infrared spectroscopy and X-ray diffraction.