Jennifer,

This is a very complex question that involves many variables, such as
the object media, the size of the space, color of the walls and
casework, other sources of light such as windows, doors, or skylights,
and the ambient lights within the space, and the sort of exhibit that
a visitor might encounter.  A conservator will recommend light and UV
level guidelines for preservation, an exhibit designer will want a
lighting plan that will illuminate not only the casework but other
elements of the design such as wall panels and labels, and a lighting
designer will want to highlight the exhibit with lights both in an
overall visual impact when a visitor enters each room and up close in
the detail of each object.

In general, since it takes time for the human eye to adjust from
bright to dark (especially in middle-aged to senior visitors), you
want to gently transition lighting levels from the moment visitors
enter the door, so that they aren't going from a very bright space
into a very dark one. Think of the difference in perception between a
room with white walls and 5 Lux light on an object verses a room with
black walls and 5 lux light on the object. I have seen stunning
exhibits with light levels set to conservation standards and
absolutely terrible ones at those same levels. You also want a color
temperature that most accurately parallels how the human eye perceives
color in sunlight - have you ever seen art or objects under
fluorescent lights? One issue I constantly deal with as a professional
objects conservator is to match any fills or color compensation in a
surface to the light that the object will be seen in - my careful
matching can turn out awful if I don't ask that question of the
curator or client. I work on some objects in corporate collections
where they'll look awful unless they are inpainted under fluorescent
lights, because that is where they reside in the various lobbies and
offices.

Since light damage is permanent and irreversible the most sensitive
media should always be the most protected, with strategies of reducing
light exposure and duration to a minimum, and having a very proactive
approach to the rotation of those objects very frequently back into
storage. This should be true for your own exhibits as well as anything
that is light sensitive that goes out on loan. Write those standards
and rotation schedule into your loan agreements. The Canadian
Conservation Institute has made available for years a light damage
calculator where you can formulate the light exposures for different
objects and media - it might even be available online now. Toby
Raphael of the conservation department of the National Park Service
has been working aggressively to do very thorough research on exhibit
guidelines that incorporate conservation into a cost-effective
strategy for smaller museums in the NPS system, and integrating both
case design and lighting standards has been one of the elements of
that. They also have that information available on CD for those who
want to purchase it. My own expertise in lighting came with the
conservation and electrification of metal chandeliers for historic
houses  (to replace the use of candles) and I contributed a paper to
the 1999 APT Bulletin that consisted on the proceedings of a
conference on Lighting in Historic Structures. There are some
excellent papers in that volume.

I would advise that if you are not going to use a skilled lighting
designer and are going to try to do this in-house, then get someone on
staff into an exhibit lighting design workshop so that someone has the
training to approach the complex issues involved.

Cheers!
Dave

David Harvey
Conservator
Los Angeles, California, USA

On 10/5/05, Jennifer Hall <[log in to unmask]> wrote:
>
> HI, I was wondering what lighting techniques or solutions anyone has for the
> proper conservation of artifacts on exhibit but also allowing visitors to be
> able to see the objects.  Thank you.
>
> Sincerely,
> Jennifer Hall
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