Double Vision

X-ray fluorescence scanning is used to uncover the secrets of Thomas Wijck’s The Alchemist. (CHF Collections)

X-ray fluorescence scanning is used to uncover the secrets of Thomas Wijck’s The Alchemist. (CHF Collections)

When Thomas Wijck first stepped onto a London dock, probably in the early autumn of 1663, the city was in the midst of a booming alchemical renaissance. Wijck’s timing couldn’t have been better. The Dutch painter of alchemical workshops found himself in high demand at court; the new king, Charles II, was fascinated by alchemy. Apart from the Great Fire of London of 1666, which Wijck most likely saw firsthand, alchemists became the artist’s most famous subject.

Looking at The Alchemist, painted by Wijck and now part of CHF’s Eddleman Collection, we see a world where the lines between living space and laboratory space aren’t clearly defined. Wijck’s alchemist is “at home” with his work, while his wife deals with the household. This arrangement must have been as familiar to Wijck as it would have been to early chemists—for artists, too, usually worked in close proximity to their families.

These workshops—alchemical and artistic—were spaces filled with tools, experiments, and works in progress. Alchemists weren’t the only ones turning raw materials into precious goods: artists made wood and canvas, oil and chalk into objects of incredible beauty. Where alchemists worked to master nature, painters mimicked it, finding ways to dazzle the eye with texture or fool it with imitation gold and jewels. Painters also worked with raw materials—pigments—that needed to be rendered and purified. Printmakers used some of the same chemicals as alchemists: aqua fortis (“strong water,” or nitric acid), used to separate metals in alchemical recipes, was applied by etchers to produce copperplates.

Wijck was both a painter and an etcher, and he obviously felt more than a passing interest in his subject. Are the similarities between painters’ studios and the laboratories they paint more than coincidence? One way to answer such a question is to learn more about their materials. Many pigments could be made by hand in the studio but would have required expert knowledge. The brilliant red vermilion—a mercuric sulfide produced through sublimation—was highly prized at this time. Artists thought of vermilion as fundamentally alchemical in nature; in his 14th-century handbook the painter Cennino Cennini insisted that vermilion could be made only through alchemy.

The technology that can unlock the secrets held in Wijck’s pigments is called XRF, or X-ray fluorescence. XRF scanners “read” the surface of the painting and report the type and amount of elements present within the paint. We already know the makeup of many historical pigments, thanks to the work of art conservators in previous generations: so, for example, we know that the blue mineral pigment azurite contains a great deal of copper. High levels of copper in a blue area of the picture—perhaps a vibrant blue sky—would suggest that azurite was present. A team of researchers from the University of Delaware, with equipment on loan from the Winterthur Museum’s Scientific Research and Analysis Laboratory, recently gathered at CHF to scan a number of Wijck’s paintings using portable XRF technology. While their research continues, some early data shows exciting potential: Wijck’s The Alchemist does, in fact, contain vermilion. The presence of this alchemical pigment is yet another connection between the studio and the laboratory. It may be that Wijck is a kind of alchemist after all: one who can even centuries later transform our understanding of art and science.

While XRF technology enriches our understanding of artists’ materials, it wasn’t invented for art historians or conservators. It was developed for industrial purposes, to sort scrap metal and to identify minerals in geological surveys. An XRF scanning unit even went into space with the Apollo 15 mission to investigate the surface of the moon.