Hello Museum folk, With the strong emphasis on "green" technology these days there has been a movement towards the use of LED lighting in cases and galleries. As part of a recent discussion on this topic on the PACIN listserv a post by Dale Kronkright - head of conservation for the O'Keefe Museum and including a quote from Jim Druzik of the Getty Conservation Institute struck an alarming cord. With both individuals permission I would like to pass that post on to Museum-L folks. Those of you who are also on the RCAAM listserv may have seen it - if so my apologies for the repetition. Obviously there are previous posts about poor CRI ratings typical of LED and the important distinction between Color Temperature and Color Rendering (in the form of a light sources CRI - Color Rendering Index) that are not included here. For people whose jobs include the responsibility for making informed decisions concerning the safe handling, packing, crating, installation, and storage of cultural materials I would recommend taking advantage of the PACIN (Packing, Art handling, and Crating Information Network) website and listserv as a resource. Anyone interested can either join the listserv themselves or simply request that those individuals who are the hands-on preventive conservation practitioners within their institutions do so. Here is the post and some additional comments provided by Dale Kronkright: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ From: Dale Kronkright <[log in to unmask]> [Add to Address Book] To: [log in to unmask] Subject: Extreme caution urged when considering LED's for illumination of light-sensitive materials Date: Mar 24, 2010 8:46 AM Attachments: Hole burning potential of LEDs.pdf unknown-135 B Below is a letter sent to the Green Task Force of the American Institute for Conservation of Artistic and Historic Works, at their request, clarifying the potential problems of using LED’s to illuminate art cultural heritage materials. Members of the task force suggested we also post this email to the PACIN list serve. First let me say that LED’s present a low-energy-of-operation alternative for the illumination of non-light-sensitive museum materials where the color discrimination of the object is not critical to its appreciation or understanding and in offices and non-collection areas. I believe the existing reported data demonstrates that LEDs are a potentially damaging light source for light-sensitive museum materials and are deficient where accurate color discrimination within the human visible spectrum is required. The deficiencies of LED light sources, both for color rendering and for their narrow emission spectra, is not new information. The CIE data first explaining these deficiencies in detail was published in 2004. I believe the manufacturers are acutely aware of these deficiencies. Jim Druzik of the Getty Conservation Institute has just returned from an NIST meeting where the efforts of the manufacturers to overcome them was frequently discussed. Unless conservators ask very pointed and direct questions, my sense is that manufacturers have not initiated discussions that reveal the risks of LED light sources to light sensitive materials. The color rendering indexes of these light sources, when tested in independent studies, has been near 60% at best across the entire human visible spectrum. Experimenters have documented considerable human impairment with color discrimination with materials viewed under both 2-phosphor white LEDs and RGBA and RGB 4- and 3- source “white” LED sources. If exposing light-sensitive materials to damage within exhibitions is to severely limited, then certainly the few times they are exhibited ought to be done so that people can accurately discriminate between the colors we are so carefully trying to preserve. To expose them to damage AND prevent an accurate sense of their visual characteristics seems to be the biggest crime of all. I will attach copies of 2006 un-filtered MR-16 halogen incandescent lamp, a 2-phosphor white LED, a red, green, blue, amber white appearing LED and a red, green, blue “white” appearing LED, each taken off a standard spectralon tile at 660 lux. Each of the SPD’s has a heavy horizontal line at 0.01W·m−2·nm−1 , the highest power output of a broad, continuous incandescent lamp. Please note that the power of the narrow wave peaks produced by the LED’s is 20% to 400% higher than the halogen MR-16 at the same light level. Since it is well established that light-sensitive materials - typically illustrated by Japanese wood block prints, dyed textiles, watercolors, pastels, color photographic images, biological specimens etc - are damaged ( ie undergo color shift such as loss of coloration – fading -, darkening, yellowing or color-shift) by radiant energy WITHIN the human visible spectrum, any light-sensitive material whose damage spectra (within the absorption spectra as opposed to the reflection spectra) contains any of these isolated LED output peaks would undergo damage at 20% to 400% faster rates than if lit at the same light levels with an unfiltered MR 16. To this information, Jim Druzik, Senior Scientist with the Getty Conservation Institute and project leader for the joint O’Keeffe Museum – GCI – University of Texas El Paso light damage prevention project adds: “It has been demonstrated that some LED mixtures will accelerate damage more rapidly on natural yellow dyes. The SPD is useful for calculating gamut area mapping and CRI - so between those two metrics one can determine color rendering. But there are no damage-activation spectra of most dyes and pigments. Because so much is piled on to narrow bands in LEDs, the possibility of hole burning is very possible and trying to be "green" with so little knowledge is Russian Roulette and the LED green committee is playing with fire. At this time I don't think LEDs are ready for prime time both from the point of view of color rendering and conservation. Clearly two LEDs with a bridging phosphor is better than all LEDs but some manufacturers have driver problems, green is mismatched for optimal color rendering, and only one manufacturer hits the Energy Star specification. I know all this because I just came back from NIST which is a hotbed of research on LED lighting and that's most of what all the current research is about. The one Energy Star qualifier does achieve an amazing 65 lumens/Watt but I didn't see it turned on so I don't know how good its color is. As you know, it could be any CCT yet if displaced off the spectrum locus for blackbody illuminants, it'll still could be a disaster. I have it on my "To Do List" to buy a few of the Energy Star qualifiers and measure their spectrum. I just got a piece of NIST software which will display two sets of Munsell swatches according to their appearance side-by-side with a reference illuminant. That might be the way to go first.” We hope this clarifies the need for using extreme caution when considering LEDs for the illumination of light sensitive materials. To reiterate our earlier point, for non-light-sensitive materials where the color discrimination of the object is not critical to its appreciation and understanding and in offices and non-collection areas LED’s present a low-energy-of-operation alternative. For light sensitive museum materials, there is no existing data that demonstrates that they are either safe or effective at the 50 to 70 lux levels commonly used to extend the life of these materials during exhibition. Dale Kronkright Head of Conservation GeorgiaO'Keeffe Museum [log in to unmask] 505.946.1041 tel 505.946.1093 fax 217 Johnson Street Santa Fe, New Mexico 87501 USA In addition to the original post Mr. Kronkright adds: It is important to grasp the fundamental fact that 50 lux, 65 lux or any light level from an LED source is NOT the same as 50 lux, 65 lux, etc. from an incandescent source. The spectral power distributions are different. Guidelines for lighting light-sensitive museum materials are based upon the spectral power distribution of most halogen-incandescent sources (e.g. MR-16, Par 38 lamps) and their fading behaviors with materials of known sensitivities, the ISO Blue Wool Standards. Since light sensitive materials generally fade first as a result of exposure to the visible light spectrum, and since most museums are aware of the need to filter for UV and IR radiation, the fading and color-shifting behaviors of light sensitive materials may be significantly accelerated as a result of absorption of the elevated narrow energy bands within the visible spectrum delivered by LED sources. I will be reviewing the latest Federally confirmed data at the DOE Energy Efficiency and Renewable Energy testing laboratory and the Committee of Illuminating Engineering Society of North America, author of the RP-30 recommended practice for Lighting Museum and Art Galleries, over the next two weeks. We may find that there are sources that do less damage to light sensitive materials than the 2007 lamp data I site in my posting. If so, I will update the AIC-Green Task force, the PACIN listserv and the RCAAM listserv and post a link to any DOE-EERE-IES joint statement to museums. ========================================================= Important Subscriber Information: The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes). If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).