I just want to add a few things to this discussion.

First. Light damage is accumulative and irreversible. The entire spectrum of light, visible, IR, and UV contains energy which can damage art and cultural objects. Conservators calculate light damage potential by plotting intensity vs. time. Both have to be managed to control light damage..

Second. Have a light survey done. Identify your good and bad areas before you spend lots of money on window treatments.

Third. Not every class of material has equally potential for light damage. A stone, metal, or high fired ceramic object can withstand more light than an object made from silk, containing fugitive dyes, photograph, paper, or a painting. So you can always take this into account when planning your gallery or exhibit.

Fourth. You also need to consider the interior lighting as well - to just focus on the windows is not enough. The best approaches involve a plan in which a lighting designer works with a conservator and exhibit designer to achieve a balanced lighting mise en scene where the overall lighting level is balanced with the light on the objects to achieve visual clarity while still providing the preventive preservation and care that we advocate for.

Finally be aware of the past. Historic houses had blinds and curtains - old book shelves had curtains - there are all kinds of historic methods for controlling light before electricity. Use them - a great point for interpretation!

Cheers!
Dave

David Harvey
Senior Conservator
Los Angeles, CA



On Thu, May 21, 2009 at 2:11 PM, carrie thomas <[log in to unmask]> wrote:
Hi Stacie - you will need to make sure that the bronze coloured plexi actually blocks the UV as well as the visible light.  It is the UV part of the spectrum (not visible) that causes the most damage to museum objects.  If you have a problem with you space heating up from direct sunlight, then you will need to determine if the product is blocking the infrared radiation (also not visible).

regards

2009/5/22 Stacie Petersen <[log in to unmask]>

We are looking at options to cover some of our single-pane windows in the original part of our building to block UV when we reinstall the gallery.  I was considering using UV film, but someone I have been consulting with said the the newer and better recommendation from conservators is to use Bronze-colored plexiglas that blocks 75-90% of visible light. 

I was wondering if any of you were familiar with the Bronze-colored plexi and have used it.  Does it change the color of light much, is it effective, is it difficult to install.  Also what manufacturers have you worked with.  These windows, which are up along the ceiling, provide much of the light for the gallery.  I would appreciate any comments.

Thanks in advance for all of your help.

Stacie

Stacie Petersen
Registrar


Roswell Museum
and Art Center

100 West 11th Street
Roswell, NM 88201
575-624-6744, ext. 13


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--
Carrie Thomas
Paintings Conservator


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