Joel Orosz writes:
Old-style tube fluorescent lights emit damaging levels of ultraviolet radiation, which will discolor paper. I do not know whether the newer compact fluorescent bulbs emit UV, or if so, at what level, but it would seem likely that they emit at least some UV radiation.
Jon Radel writes:
I believe the short answer is: Yes, fluorescent lights put out more ultraviolet (UV) light than incandescent lights, but if you've got windows in your library, even indirect sunlight is probably doing considerably more damage than fluorescent lights will ever do. Particularly if you turn the lights off when you don't need them.
To be a bit more precise, GE likes to reference a NEMA (National Electrical Manufacturers Association) study that found the UV exposure at typical office fluorescent light levels for 8 hours was the same as slightly over a minute of sunlight on a clear July day in Washington DC.
Since this is a problem that's been around for a long time (particularly the issue with sunlight), and not everyone likes living in a cave with black-out paint on the all the windows, there are products for filtering out UV light. As an example, if you go to www.universityproducts.com and search for "light filters" you'll find UV filters for full-sized fluorescent light tubes; I have no idea how well they'd trim to fit compact bulbs but I suspect it's not very practical. If you search for "uv filter" you'll find film to be applied to windows, which blocks 95%+ of the UV light. It looks like it may be the same stuff I can get for slightly less money at my local Home Depot.
I'll also note that another up-and-coming replacement for incandescent bulbs are lights based on using multiple super-bright LEDs. I understand that these can have very low UV output, though the details appear to depend on the technology used to make the "white" LEDs.
P.S. While I usually find spelling flames a waste of time, I'll note that while "florescent" passes the spellchecker test, it actually means something quite different than "fluorescent" and leads to musings about verdant plants living under spectrum-balanced fluorescent lights--but that may just be me.
Sorry I missed that one!
Chris Salmon writes:
A few thoughts regarding the question of fluorescent lights, ultraviolet radiation, and damage to books:
I have been extremely concerned about fluorescent lighting and fading of various collectibles, including books, because uncovered fluorescent lights are a source of UVA (ultraviolet light of a certain spectrum). Fortunately, I've learned that covered or filtered fluorescent bulbs should help block much of the emitted UV light.
When considering the care of rare books and other collectibles susceptible to damage from fading and photoaging (furniture, photographs, prints, documents, rugs, etc.) it's useful to bear in mind that UV light only accounts for about 40% of fading. Heat accounts for about 25%, visible light about 25%, and miscellaneous other factors (including humidity) about 10%. A cool, dark environment with a low relative humidity is ideal. The best range of temperatures is 60-70 degrees.
Controlled humidity is extremely helpful. Relative humidity of 45-60% has been recommended, although the track record of low humidity in Egypt in preserving fourth century papyri--and even older mummies--is obviously extremely impressive. Effective preservation of mummies along the arid coastal plain of Peru is also well documented.
Keep vulnerable collectibles such as artwork and books out of direct sunlight. Of course, window treatments (opaque curtains or shutters) are helpful. Window film (e.g., from 3M or Huper Optik) can block up to 99.9% of UV light, much heat, and significantly reduce electric bills. Some films are designed to protect against shattering, and can reduce glare on computer monitors/laptops or TVs. I've done some recent research on film and am having it placed on all of the windows of my Arizona home. Even with the film in place I will keep fragile objects out of direct sunlight and limit artificial light to a reasonable minimum in sensitive areas. I carefully control temperature year round. High humidity is not an issue for us here!
To read the earlier E-Sylum article, see:
QUERY: IS FLORESCENT LIGHTING HARMFUL TO BOOKS?
Wayne Homren, Editor
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