Matthew, as it happens, I have a fair bit of information about light control in my files, including discussions on this listserve dating back a number of years. I don't mind updating some of what I have offered before.
Without knowing the details of your building, I would encourage you to install light control measures that will give you ultraviolet-filtering at all times, with options for reducing the visible light further. Filming the windows is handy, because once it is installed, you don't have to concern yourself with it again. Well, in truth, it does not last forever, and eventually you or someone else will have to try and remove it from the glass, a thankless task, I have been assured by those who have done it (or attempted to do it). I used it on one small gallery window, and on a dozen very large acrylic panels mounted outside some original (bronze-framed leaded glass windows; we anticipated the outdoor acrylic and film would last about seven years, but it held up for ten (in a seaside location). Then in recent years we were able to install bronze-framed, architectural glass protective windows -- quite costly, but suitable for the building, and as close to "permanent" as we could find.
There are many permutations to be considered, from architectural glass to filtering and screening shades of many kinds. The latter are the least costly and the most flexible, in my experience. In one of our museum buildings we have used: mylar filtering shades; woven light-reducing shades; mylar filtering panels (without shade rollers); acrylic filtering panels; drapes and curtains; temporary blackout panels; ultraviolet-filtering storm windows; and blackout shades. It's a big building, with many different kinds of spaces. In another building that has wooden sash windows, we used panels of UF3 acrylic, UV-filtering and visible-light-reducing; the panels were hung on each sash with small brass screws.
I assume that you would like to maintain a view to the outdoors, and so I suggest one thing to try is a double installation of shades, with transparent mylar filtering shades closest to the glass. Choose the darkest tint that people find acceptable, because visible light is damaging to delicate materials, though not to the extent that UV can be. On the inside, try mesh shades, to reduce the incoming light level even more. It might be wise to try an installation on a single window, although some people may see the result as "too dark". I can tell you with some certainty that a full installation is seldom seen as too dark, because the illumination in the space is then fairly even, without any bright spots. If you would like to look at a vendor for this sort of thing, try Solar-Screen (solar-screen.com); they can furnish you with brackets for hanging double shades. I think that curtains and acrylic panels were the only things we did not obtain from Solar-Screen.
It would be difficult for me to tell you what worked the best, because we seemed to have good results in different contexts. If you have had difficulties with people saying it was too dark, you might want to consider mylar panels, or acrylic panels, which are not intended to be easily removed without tools, once they are mounted. And I would hope that if you were able to control the light everywhere, the idea that it is "too dark" will be less of an issue, because the light would be even everywhere, without distracting bright spots. Perhaps I have been particularly fortunate, but in my own and clients' museums, I never received any complaints that control of natural light was too extreme. One of my best days included a trustees' walk-through in our largest building, and one elderly trustee asked whether a room might be too bright -- this was after we had installed all the filtering, darkening shades, without mentioning it beforehand.
Please feel free to contact me if I may be of help.
Bruce
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Bruce MacLeish
Curator Emeritus, Newport Restoration Foundation
Cooperstown NY
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Original Message:
Sent: 01-15-2021 11:28 AM
From: Matthew Young
Subject: Protecting Art from UV Light
Hi, I'm new to the group. I manage a 7,500 sq/ft art gallery in Lake Charles, Louisiana. Our historic property was badly damaged during Hurricanes Laura and Delta this past fall. Prior to the storms, we used blackout fabric in the windows (combined with wooden blinds) to reduce harmful UV rays in the galleries. I'm hoping to find another option that will help filter light without ENTIRELY blocking out the windows. Do any of you use Solar Control Tint as a way to do this? Or would you recommend a better alternative. We're renovating the property beginning in February, and your thoughts are appreciated.
Thank you in advance.
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Matthew Young
Director of Cultural Affairs
Lake Charles, LA
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