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Question asked 2023-01-20 01:04:53 ...
Most recent comment 2024-03-29 13:42:45
Art Conservation Topics
ASTM
Drawing Materials
Environment
Matting, Framing, and Glazing
Oil Paint
Other
Pastel
Pigments
Varnishes
Watercolor
Dear MITRA folks,
To make a long story short, a solo show space that I have been offered consists of a long wall on one side of a wide corridor/lobby where art is installed, and a long window opposite that allows light to hit the art wall all year long, with distracting shadow patterns of branches for good measure. When I voiced my concerns, I was told that there is a tint on the windows with "5% transmission" that cuts out 99% of the UV light rays. Would that be sufficient to keep any sunlight damage from happening over the course of a two-month period exhibit? Under normal conditions with brief periods of light coming in at only a certain time of day I would think so, but this window allows sunlight in all day long.
I could help mitigate the risk by using varnish with UV protection where applicable or frame with UV protection glass where glass will be used, but I am wondering if oil, watercolor, or pastel should be out of the question for this show and that charcoal drawings might be a "safer" option? (My largest body of charcoal drawings were executed with non-traditional, homemade charcoal, if that makes a difference.)
All of my materials are professional quality, and for the most part I use lightfast pigments -- all the oils are lightfast ASTM rating I -- though occassionally the watercolors made with natural pigments and crushed gemstones are graded ASTM II.
Many thanks in advance for your guidance!
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Moderator Answer
(gmarcus)
Hi! One question I have is about the light level - I'm guessing from your description that it is quite high, but without measurement it will be difficult to guess. The amount of light exposure your object will receive is cumulative, so things like the time of year (and therefore the hours of light exposure per day), and whether the light is direct or indirect, will make a difference. I'm happy to hear that the gallery has UV filtration on the windows, but you're right that visible light can still cause damage. A guideline we use for museum exhibition is no more than three months of exposure at 5 footcandles or less every five years, for things like watercolor or pastel, but this is somewhat arbitrary and would be difficult to apply in a gallery setting.
There are a few ways to approach this - either acceptance, or rotating objects on and off exhibition (so objects might be up for a month before being switched out with something else), or choosing charcoal and varnished oils or other (comparatively) less lightfast media. Two months in winter or early spring would also mean much less light than two months in mid-summer, so maybe the timing of the show can be considered.
Best wishes,
Gillian
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Moderator Answer
(koo schadler)
To clarify, the UV protection in varnishes does not protect artwork from UV light; rather it's there to protect the varnish so it doesn't degrade as quickly. There are many types of framing glass with varying levels of UV protection - from 45% to 99% UV light filtered out. The best, Museum Glass, can cost twice as much as regular glass. Finally, there is some question how lightfast modern, organic, synthesized pigments actually are, even those rated ASTM I. Testing is needed; see this article: https://www.naturalpigments.com/artist-materials/pigments-artists-paint-lightfast
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Moderator Answer
(gwatson@goldenpaints.com)
Just wanted to follow up to mention that while UV light stabilizers definately help protect the binder in the varnish itself, we have many examples of UVLS containing varnishes that have also protected the colors and materials below. If you are using artist grade pigments, rated LF1, they will already have good stability and additional of a varnish with UVLS should exponentially increase the resistance to change.
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Moderator Answer
(brian baade)
Really when you take everything into account, UVLS varnishes
do protect the pigments. Varnishes absorb much of the UV radiation. This is why
natural resins degraded so abruptly and also why more fully coated pigments in
oil fare better than the more sparsely coated pigments in watercolor. In
essence, the surface organic materials take the brunt of the radiation.
So if this is true AND the UVLS is protecting the varnish
from deterioration, it is also protecting the pigments and binder proper. It
may be round-about but it is practically the case as well.
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Moderator Answer
(koo schadler)
Thanks, Brian and Greg, for the clarification regarding UV protection in varnishes.
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Moderator Answer
(brian baade)
A turbid curtain may not filter out all of the UV but it would remove a
large proportion as well and some of the visible light.
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