LED Lighting: Fact and Fiction

Thanks to conservators Paul Himmelstein and David Goist for sharing their expertise on lighting and light filtering at the North Carolina Museums Council’s annual conference last week.

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Fact:

• LED lights do not emit ultra violet light. Consequently, they are safer for collections preservation than fluorescent lights.
• LED lights generate much less heat than incandescent bulbs—another preservation advantage.
• LED lights will save institutions money in electric bills and institutional labor costs. Because they emit less heat than incandescent lights, their use will decrease the need for cooling energy.

Fiction:

Several news articles published early in 2013 asserted that LED lighting was “the culprit” behind the fading of the fugitive yellow pigment in Van Gogh’s works, “Sunflowers” being the most renowned

Correction:

Flaws in both the research and the reports of it mistakenly marred the reputation of LEDs. An LED manufacturer quickly responded to the Huffington Post’s article and asserted that the lights used in the research were not LED at all but another type of lighting (xenon) that emits ultra violet light. The recent articles also neglected to discuss that the fading yellow pigments in Van Gogh’s works were old news, predating the switch to LED lights.

Last month the Smithsonian American Art Museum Lunder Conservation Center responded with the program “Gallery Illumination: LED Lighting in Today’s Museums.” Two conservators, a lighting engineer, and a lighting designer presented on the claims about LED effects on Van Gogh pigments. Excerpts follow from the presentation printed on the PACCIN listserv:

In 2012 a team of European scientists and conservators published the results of their work on chrome yellow pigments used by Vincent Van Gogh…Unfortunately, the research team also made the very strong, but substantially untested, assertion in a press release that the pigments in question are likely to be selectively sensitive to the white LEDs increasingly used in museums. Significantly, they did not draw this conclusion in their peer-reviewed publications, possibly because it was based on highly unrealistic accelerated light exposure test using a test illuminant completely unlike an LED. In fact the accelerated aging light source is unlike any other museum lighting short of displaying the paintings outdoors, without glazing, in the sun…Astonishingly, given the importance of the issue they have raised, they did not actually test or even model the damage potential of…LED, nor did they compare its putative effect with conventional tungsten lighting, which they neglected to explain, must in principle also affect the pigments to a similar degree.

Finally, to compound the misinformation…the press release included an LED spectrum with the label “[e]mission spectrum of a typical ‘white’ LED, containing a substantial portion of harmful blue light”. The spectrum shown in fact is not typical of – nor even recommended for – any light-sensitive artifacts. They also omitted the important qualifier that in order to render the colors of these paintings satisfactorily any illuminant must contain a proportion of “harmful blue light”, not just LEDs. For works of art on paper, textiles, decorative arts, and paintings with known sensitivity issues, the types of LED recommended by conservation scientists are those that most closely resemble the visible portion of the spectrum of tungsten lighting that, for the most part, have been used for the last century to illuminate museums. These LEDs…represent no greater risk than the lighting they replace; indeed there is some research indicating that they are marginally safer.

We believe it is wrong both in principle and on the available evidence to characterize contemporary LED lighting in general as less safe than the traditional alternatives; and it is irresponsible to publicly imply that museums have begun to phase them in without considering their relative damage potential. In view of the energy and many other advantages that LED lighting offers, and the availability of a wide range of white light LEDs with virtually identical spectral properties to tungsten lighting, it would be better argued that museums would be foolish not to consider their adoption.

 Have you considered the investment of switching to LED lighting in your institution?