Past posts of The Art Doctor have explored the field of art conservation as a combination of art history, craftsmanship, and science. On Saturday, March 25, Colby College and the Jackson Laboratory hosted the Maine State Science Fair. As part of the STEAM (Science, Technology, Engineering, Art, and Mathematics) initiative, the Colby College Museum of Art hosted three sessions on the synergy between art and science. As art conservation forms a natural bridge between the sciences and art, Nina Roth-Wells (aka The Art Doctor) taught a workshop to high-school students and their teachers focused on using the electromagnetic spectrum to examine works of art from Colby’s collection. In this installment of The Art Doctor, Roth-Wells shares some highlights from this exciting workshop.
While many of us may not be familiar with the technical terminology of the electromagnetic spectrum, we all experience electromagnetic waves constantly in the form of light, colors, radio waves, microwaves, and heat. What separates these waves is their wavelength.
Color is a key part of what we see when we look at works of art. When we see a color, it is the function of a particular wavelength of light being reflected back at our eyes. When we see something that looks red to us, that is because that material absorbs all the wavelengths except the wavelengths at 700 nanometers, and those wavelengths of light are reflected back into our eyes. We experience the wavelengths from 400 to 700nm as visible light and those wavelengths are responsible for all the colors we see. Waves, however, can also exist beyond the visible spectrum. At longer wavelengths above 700nm we experience infrared radiation as heat. Below 400nm exist ultraviolet wavelengths. Some animals like bees can see ultraviolet light; humans can see fluorescent materials in UV light. For example, both white fabrics and tooth whiteners have florescent materials in them, which is why your teeth and shirt looks so bright when you dance under a black light at a disco. We also physically experience UV radiation from sunlight and, as you’re probably painfully aware, overexposure to UV radiation can cause sunburn.
In examining works of art, we can use the electromagnetic spectrum to our advantage.
X-rays, one of the longer categories of electromagnetic waves, can reveal underlying layers that are not visible on the surface of a painting, as was the case with the Museum’s Portrait of Catherine Margaret (Kitty) James by Ezra Ames. X-rays only work, however, if these layers are X-ray opaque, meaning that they block X-rays. In a medical X-ray, for example, bone, visible in the scans, is an X-ray opaque material, while skin is an X-ray transparent material, through which the X-rays pass. X-ray opaque pigments are generally nonorganic, such as those made from metals and minerals. In this detail from the X-ray of Kitty James, white lead, an X-ray opaque pigment, appears as white details.
Infrared light can penetrate between surface and support to reveal underdrawings by entering the uppermost paint layers. Below see graphite inscription in this sample painting that I created for teaching purposes and grid lines across the face of Variation on “La Vachere” by Theodore Robinson, evidence that helps us reconstruct the artist’s process.
Both the students and teachers who participated in the workshops were impressed with the integration of science and the arts. One of the chemistry teachers was particularly thrilled with such practical and observable ways for students to participate and experience the electromagnetic spectrum, a topic typically taught through abstract concepts in the classroom. This visit was able to provide a much more hands-on approach.