Comments on: Seeing Artwork in a New Light http://blogs.getty.edu/iris/seeing-artwork-in-a-new-light/ The online magazine of the Getty Fri, 24 May 2013 20:59:49 +0000 hourly 1 By: Lisa http://blogs.getty.edu/iris/seeing-artwork-in-a-new-light/#comment-675392 Lisa Sat, 02 Feb 2013 13:55:56 +0000 http://blogs.getty.edu/iris/?p=4510#comment-675392 Dear Jim, I hopoe you don't mind me asking some questions. I was interested to read about your studies on albumen photograph dyes. Did the LED's have any effect on the albumen of the photographs? 1. Is a lux reading for LED lights the same as for other forms of light. Do we need to look at LED's differently when taking loght readings? 2. Even if an LED light does not emit UV, does it still have the same light damaging effects on paper such as bleaching and or yellowing that other light forms have on paper. 3. Some lighting people say that one can use LED's to display light sensitive media where one could not have done that in the past, but correct me if I am wrong but cutting out UV does not stop paper deteriorating? 4. What are the long term effects of LED light sources on cellulosic material, does it have the same long term effects as other light sources? Thanks Lisa Dear Jim,
I hopoe you don’t mind me asking some questions. I was interested to read about your studies on albumen photograph dyes. Did the LED’s have any effect on the albumen of the photographs?

1. Is a lux reading for LED lights the same as for other forms of light. Do we need to look at LED’s differently when taking loght readings?

2. Even if an LED light does not emit UV, does it still have the same light damaging effects on paper such as bleaching and or yellowing that other light forms have on paper.

3. Some lighting people say that one can use LED’s to display light sensitive media where one could not have done that in the past, but correct me if I am wrong but cutting out UV does not stop paper deteriorating?

4. What are the long term effects of LED light sources on cellulosic material, does it have the same long term effects as other light sources?

Thanks

Lisa

]]> By: Melissa Abraham http://blogs.getty.edu/iris/seeing-artwork-in-a-new-light/#comment-64543 Melissa Abraham Fri, 30 Sep 2011 15:57:26 +0000 http://blogs.getty.edu/iris/?p=4510#comment-64543 Hi, Andy - Thanks for your comment and interesting question! Jim Druzik had this answer: "At the present time all white LEDs used in museums, or being contemplated for that purpose, utilize a blue LED in conjunction with a broadband white phosphor. The color rendering index for these types of lamps generally range from the mid-80s to mid-90s. The excitation of fluorescence using an LED chip with significant UV are not used in museums. Multiband LEDs like RGB and RAGB do not have the color rendering of white LEDs. They tend to be particularly poor at rendering yellows as well as the light sources they would be replacing indoors. That is not to say that some day they may be competitive. The most common forms of white phosphor LEDs in museums not have little, if any, light below 420-440 nm and drop off beyond 660 nm, making them negligible sources of both UV and IR." Hi, Andy –
Thanks for your comment and interesting question! Jim Druzik had this answer:

“At the present time all white LEDs used in museums, or being contemplated for that purpose, utilize a blue LED in conjunction with a broadband white phosphor. The color rendering index for these types of lamps generally range from the mid-80s to mid-90s.

The excitation of fluorescence using an LED chip with significant UV are not used in museums. Multiband LEDs like RGB and RAGB do not have the color rendering of white LEDs. They tend to be particularly poor at rendering yellows as well as the light sources they would be replacing indoors. That is not to say that some day they may be competitive. The most common forms of white phosphor LEDs in museums not have little, if any, light below 420-440 nm and drop off beyond 660 nm, making them negligible sources of both UV and IR.”

]]> By: Andy Drews http://blogs.getty.edu/iris/seeing-artwork-in-a-new-light/#comment-61350 Andy Drews Mon, 19 Sep 2011 22:51:48 +0000 http://blogs.getty.edu/iris/?p=4510#comment-61350 LEDs seem like the clear path forward as the article indicates. Since "white" sources can be made without the production of UV light (mixing of three or four color LEDs), it should be possible to sharply curtail the degradation by UV that fluorescent or "daylight" incandescent lights produce. However, some "white" LEDs use a UV emitter in conjunction with a phosphor - how much leakage of UV occurs compared to conventional fluorescent bulbs? For three and four color visible LEDs, how do the degradation rates compare? LEDs seem like the clear path forward as the article indicates. Since “white” sources can be made without the production of UV light (mixing of three or four color LEDs), it should be possible to sharply curtail the degradation by UV that fluorescent or “daylight” incandescent lights produce. However, some “white” LEDs use a UV emitter in conjunction with a phosphor – how much leakage of UV occurs compared to conventional fluorescent bulbs? For three and four color visible LEDs, how do the degradation rates compare?

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