Paint Delamination as a Result of Zinc Soap Formation in an Early Mondrian Painting

Abstract

The Evolution triptych by Piet Mondrian (1911, oil on canvas, Gemeentemuseum Den Haag) presents a case study of a painting that is seriously affected by zinc soap formation, which has resulted in paint delamination and paint loss, particularly in the cadmium yellow paint areas. The paint is extremely fragile, which makes the paintings vulnerable with regard to handling and treatment. This paper focuses on the analytical research of the painting using various state-of-the-art and novel macro- and micro-imaging techniques. Macro X-ray fluorescence scanning (MA-XRF) revealed the presence of cadmium (Cd) and zinc (Zn) in the affected yellow paints. Paint cross sections of both affected and intact paint areas were investigated using light microscopy, scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), attenuated total reflection Fourier transform infrared (ATR-FTIR) micro-imaging, and synchrotron photoluminescence (PL) micro-imaging. With the help of these techniques, the cadmium yellow pigment could be identified as a mixture of cadmium sulfide and cadmium oxalate. The presence of zinc white was established in areas where the yellow paint film is degraded, while the intact areas of yellow paint do not contain any zinc white. In samples of the degraded paints, it was demonstrated that high concentrations of zinc soaps have formed, accumulating at interfaces. This has caused local chemical and physical changes of the paint resulting in delamination between paint layers.