First of all, with relation to the UV issue:
So far as I know, Alistair is correct about incandescents not having an
appreciable UV component. However I do cringe at his statement that the
Infra-red aspect is "harmless". It's all relative. If your incandescent
source is too close to your object, or especially if it is in an enclosed
space with your object (like a case), then the IR becomes very important as
it will heat up your object which will hasten deterioration. Any case with
a light source in it, particularly when it is incandescent or halogen, needs
to be properly ventilated to prevent heat build-up. The sensitivity of your
object to heat and its proximity to the light source also need to be
considered. Ventilation will only prevent convective heating (when the bulb
heats up the air around it, which then circulates in the space). It will
not prevent radiant heating (when the IR energy heats the object directly).
In addition, the radiant heating will only occur on the side facing the
light source, and the uneven heating will cause warping stresses which may
lead to further indirect damage.
Next, with relation to the issue of copying photographs and copyright
issues:
Someone on this list said that providing a copy of a photograph to someone
is not giving them copyright. True, the possession of the photo itself does
not grant any rights, but if that photo is for use in an exhibit or
publication, then you are, in fact, granting a limited use, non-exclusive
copyright. What you are not granting is the ability for that person to
extend the copyright to someone else. A technicality for non-lawyers (such
as myself), I suppose, but if you have to work around copyrights, I think
it's important to be aware of. Also: Modern copyright law does not
consider a single "right" to a work, but rather a bundle of rights
concerning such things as: performance/display, reproduction,
modification.... With the modification of copyright law to bring US law
into agreement with European law, artists now retain more residual control
over their creations, even after they are sold/donated.
(Necessary?) Disclaimers:
I am neither a conservator, nor a lawyer, but both of the above issues were
heavily stressed in my coursework. As with all advice, contact a trusted
expert for specifics on your case!!
Larry Burke
Historical Society of Western Pennsylvania
-----Original Message-----
From: Alistair Kwan [mailto:[log in to unmask]]
Sent: Friday, January 19, 2001 11:41 PM
To: [log in to unmask]
Subject: Re: museum lighting
Gloucester County Historical Society wrote:
>
> I am director of a museum that's currently being rewired. I am
> familiar with plastic sleeves put over florescent lights to cut down
> on UV. How can I filter UV from light coming from incandescent
> lights? I mean table lamps, track lighting, chandeliers, etc. There
> is new UV blocking film on the museum's windows, too. Thanks for your
> advice.
Before investing in filters, have you calculated whether there is an
appreciable UV component to worry about? For common incandescent
filaments, the UV component is very small, and can be lessened by
running them at lower temperatures (e.g. by using lower voltage
supplies.) In fact, if you analyse the spectrum of common incandescent
light, you'll find that most of it is invisible and harmless infra-red.
So it might be worth checking whether the filaments in use do in fact
present a problem.
If you have a pre-determined standard threshold for tolerable UV
exposure, then it would probably not be very difficult to calculate a
sufficiently accurate estimate of whether the threshold is exceeded. A
good student of 2nd-year university physics should be able to do this
with little difficulty, given some spatial data about your museum.
----------------------------------------------------τΏτ-
Alistair Kwan -
[log in to unmask] / [log in to unmask]
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