From: Greg Schmitz (gws1@columbia.edu)
Date: 02/23/01-03:41:16 AM Z
Judy, exposure for purposes of calculating pigment exposure is similar
to that of film.
E = I x T
where E = exposure
I = intensity
T = time
A meter reading taken at my studio desk with overhead fluorescent bulbs
shows that aprox. 143 lux are striking the surface. Thus, for example,
143 lux * (10 hours * 60 minutes * 60 seconds) = 5148000 lux seconds
(15.45 LOG EXPOSURE). That 10 hour exposure would be the same as
pointing a light source emitting 5,148,000 lux at your artwork for 1
second or an 85,800 lux source for 1 minute or a 14,300 lux source for
1 hour.
UV has been considered a culprit in fading because, I believe, it
carries more energy than the longer wavelengths. That said I think
conservators have become even more conservative in recent years,
treating any and all light exposure as damaging to artwork over the
long hall. Somewhere I saw a calculation of how much energy the Mona
Lisa would be exposed to if every other person who looked at it over
the course of a year took a flash picture of it. I don't remember the
final calculation but it was equivalent to leaving the painting out in
the sun for a considerable length of time.
-greg
On Fri, 23 Feb 2001, Judy Seigel wrote:
> Bob, do you mean that in ordinary home situation, that is, not museum lit
> all day, but interior with some artificial light, pigments that have top
> rating fade? I have fluorescent ceiling light over computer MANY hours a
> day, at press time maybe 16 or so -- a small painting in this light for,
> probably 25 years... hasn't faded that I NOTICED, and not under glass.
>
> ????????????????????????????
>
> Judy
>
----------
Hope for the best, but be prepared for the worst.
US ARMY SURVIVAL MANUAL
----------
This archive was generated by hypermail 2b30 : 03/06/01-04:55:40 PM Z CST