A research of the departments of Chemistry and Physics of the Polytechnic of Milan has uncovered that Vincent Van Gogh used a particular fluorescent white pigment in one of his watercolor paintings that gave this color a greater intensity.
The 1888 painting “Breton Women and Chlidren” was analyzed using particular techniques for measuring the spectre of reflectance and fluorescence, which has revealed an intense green fluorescence corresponding to the white areas. Researchers have developed an instrument called “multispectral imaging system” that allows them to detect the most subtle color shades in a painting and also to verify its stability when environmental conditions change monitoring it at different times.
This fluorescence was created using zinc oxide and traces of zinc sulfide or other metallic impurities that made the pigment assume the behavior of a semiconductor with the subsequent generation of this effect. It’s no coincidence that in the late nineteenth century and early decades of the twentieth century substances such as zinc sulfide were used in cathode ray tubes of various scientific instruments. These substances in fact generate a white-green light when they get excited by electron beams.
It’s known that Vincent Van Gogh experimented with various solutions in the creation of colors using the developments of chemistry at the end of the nineteenth century. Many pigments created with what were new technologies were less expensive and this was another reason to use them for an artist who was notoriously broke.
Now the researchers goal is to determine whether this fluorescent white was used only on this watercolor painting or if Vincent Van Gogh used it in other works. The interest in this research isn’t simply in the curiosity to know precisely the composition of the colors used by Van Gogh. The research also analyzed the stability of the fluorescent white to see if there’s a risk that this color is deteriorating.
Last February, a research on the alteration of the yellow color of Vincent Van Gogh’s famous sunflowers allowed the scientists to understand why that color is slowly turning brown, a key point to improve the conservation of some paintings. Clearly if we want to preserve those masterpieces of painting and at the same time we want to keep on exposing them to the admiration of the people we must also be sure that we can keep them in conditions that avoid their deterioration.