Diane,

Thanks for throwing my hat in the ring!

You need to be concerned about the total electromagnetic spectrum
produced by light energy. UV is the most damaging but the other
components of the light spectrum incur damage as well.

Simply put, light damage is cumulative and irreversible. It isn't only
the intensity but also the duration. So just cutting down on UV or on
the total amount of light energy helps alot but not if you leave those
lights on ALL the time.

There is a formula for calculating light damage - I think it is still
available on the CCI web site (Candian Conservation Institute)

Damage not only happens to paintings and prints, textiles,  and other
sensitive decorated media, but also very often to furniture in
historic houses as well. Finishes can be literally blasted and
"bleached" by harsh direct sunlight.

People two hundred years ago were well aware of light damage - many
historic housekkeping books recommend closing blinds, covering
furniture, and having curtains within bookcases, to mitigate the
damaging effects of the sun. Those are ALL simple things that you can
do in your historic house and that activitiy is a great opportunity
for public interpretation and education.

Survey your house, site, or gallery for the the worst sources of light
and potential damage and throw your efforts and resources and planning
there. So if you have east or west facing windows, guess what? Maybe
you don't put the painting on the wall opposite that window!

In galleries and traditional museums there are a wealth of strategies
that work well to manage light sensitive collections, their exhibition
and storage. And it all does not have to be all high-tech and
expensive. Just understand the issues and develop a sensible plan to
preserve your collections as best you can within your resoruces.
Believe me - if you do a little label or even an exhibit panel on
light damage to explain to visitors they will truly appreciate it.

Cheers!
Dave

David Harvey
Conservator
Los Angeles, California

On 10/14/06, Diane Gutenkauf <[log in to unmask]> wrote:
> I would caution you not to confuse UV with visible light. You can't measure UV
> output with a standard light meter and, as I'm not a physicist, I don't know if
> reducing the amount of visible light (footcandles) will also diminish UV. I
> suspect it won't make any difference, given the wavelenghts of UV rays vs.
> visible light rays. You don't mention how you know that the UV filters don't
> reduce output enough. The tubes sold by Light Impressions claim to reduce UV
> by 92%. That seems pretty good to me. Perhaps the only way to reduce it
> completely is to switch away from light bulbs that emit UV. Then your only
> worry is light level in the visible spectrum.
>
> Check with the standard sources (University Products, Gaylord, Light
> Impressions, etc.) for flourescent tubes with built in UV protection. I can't say
> I've ever seen any.
>
> (Hey Dave, any ideas?)
>
>
> Diane Gutenkauf
> [log in to unmask]
> Director
> Robert R. McCormick Museum
> Wheaton, IL
>
>
> On Fri, 13 Oct 2006 12:27:26 -0400, Jamie Smith
> <[log in to unmask]> wrote:
>
> >Hi all,
> >We are trying to find better light bulbs for our exhibit cases. Has anyone
> >come across light bulbs that put out less UV than using florescent bulbs
> >with UV filters?
> >We are trying to find something that might fit our existing light fixtures
> >which are four feet and use T-12 bulbs. Any leads on vendors that might
> have
> >something that would work for us would be appreciated.
> >
> >Many Thanks,
> >Jamie Smith
> >FASNY Museum of Firefighting
> >=========================
>
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