Paul Whitmore, director of Carnegie Mellon University’s Art Conservation Research Center (ACRC), has developed a portable device that can be used to determine how exposure to visible light and ultraviolet (UV) rays affect the colors on a work of art, providing vital information that can be used to better preserve the artwork.
The device, called a micro-fading tester, is based on technology developed by Whitmore in the mid-1990s. The tester uses a xenon lamp to deliver an intense beam of light through a fiber-optic and onto the artwork. Exposure to this bright spot of light causes fading at an accelerated pace, for the pinpoint-sized speck of the art receives many years’ worth of light in the span of only a few minutes. Another fiber-optic captures light reflected off of the art being tested and sends it to a spectrophotometer, and the color of the tested spot is calculated and recorded each second during the light exposure.
Testing how the color reacts to this brief dose of intense light indicates how the art would fade under normal viewing conditions over the course of decades. Knowing how the colors will react, caretakers of the artwork can then decide how best to exhibit it to minimize fading.
Through a grant from the National Center for Preservation Technology and Training (NCPTT, National Park Service), Whitmore was able to develop an enhanced version of his original micro-fading tester. The original version was only able to test the impact of visible light exposure. By modifying the device by using mirrors rather than lenses to focus the light from the xenon lamp, the new device can test the effects of exposure to a wider range of light wavelengths, including UV rays.
According to Whitmore, visible light is more likely to fade unstable colors – pigments that fade quickly. More stable colors, however, are much more susceptible to damage from UV light. Using the new micro-fading tester will allow predictions of color fading from UV exposure. The owners of the art would then know better whether the colors might be preserved by installing protective measures, like UV-absorbing coatings on windows or UV-absorbing glazing over framed works.
The new micro-fading tester is also much smaller than Whitmore’s previous model. Since the original was designed to be used in a laboratory setting, it was based on larger laboratory equipment that was difficult to transport. The new tester uses smaller, more portable equipment that fits into a case the size of a lunchbox. Whitmore hopes the reduction in size and the ability to determine the effects of UV light will encourage more people to use the tester in the field, taking it to anywhere art may be.