Comparative study of the speckles syndrome affecting four Magritte’s oil paintings from 1927

In the frame of the on-going research project Magritte on practice, the sixty-three paintings from the Magritte Museum collection (Royal Museums of Fine Arts of Belgium) are systematically investigated through complementary analytical and imaging methods. On this occasion, the presence of dark round stains looking like speckles, has been noticed on the paint surface of four 1927 oil paintings, namely La voleuse, Le démon de la perversité, L’homme du large and Le joueur secret. When observed under digital microscope, those appear as dark micro-cracks forming concentric cobweb-like networks, with dark accretions and with or without whitish protrusions. The proliferation of such dark stains appears as a typical visual damage, occurring in Magritte oil paintings dating from 1927. Indeed, further 1927 Magritte’s oils on canvas, for instance, L’assassin menacé from the MoMA (New York) and Le sens de la nuit from The Menil Collection (Houston), exhibit the same visually disturbing alterations, referred here as speckles syndrome. Duffy et al. [1] have pointed out the probable linkage between the visual damages observed on L’assassin menace, and the aggregates of metal soaps formed at the painting surface.
In the present study, La voleuse, Le démon de la perversité, L’homme du large and Le joueur secret, have been investigated in parallel and in the same experimental conditions, by means of non-invasive imaging and analytical methods, including digital microscopy, UV and Vis high-resolution imagery, FTIR, RS, pXRF and MA-XRF techniques. The objective of this research was to collect technical and compositional information, sufficiently abundant and significant, to formulate substantiated conclusions about the painting materials and the mechanisms involved in the speckles syndrome. The comparison of the acquired analytical data and images allowed highlighting several common denominators between the four damaged paintings. For example, the speckled surfaces always contains Ca- and P-based black pigment (bone or ivory black), unidentified chlorinated compound(s) and lead white and/or zinc white. Interestingly, the FTIR spectra recorded from speckled areas and from unaffected surfaces tend to evidence the presence of metal soaps in both cases.