Meg Geiss-Mooney writes:

>You must also be concerned on how these UV light fixtures are oriented in
relation to the viewers. UV light is very damaging to eyes. When we
conservators are using them to examine artifacts (the lamps are pointed at
the object briefly), we were protective goggles.>

in reply to:

>>Hello all, We have a group of people that would like to donate some UV
light fixtures to illuminate some extremely large paintings that will
floresce (no idea how to spell that) when lit.  I am concerned about
prolonged exposure to UV light, even if the paintings were "meant" to be
displayed in that light.>>

It is important that you determine whether the UV light fixtures emit
short-wave or long-wave ultraviolet radiation.  Go to
http://www.uvminerals.org/spectrum.htm to read about short-wave and
long-wave UV.

Some materials absorb UV radiation, which excites electrons, making them
unstable.  This absorbed energy can cause chemical bonds to break, is
converted to heat, or is converted to light as phosphoresence or
fluorescence.  The time interval between absorption and fluorescence is
measured in millionths of a second.  Visible fluorescence can be seen by
humans; ultraviolet radiation cannot.

Short-wave UV is used in many natural history collections -- behind glass --
to excite fluorescence of mineral specimens, but should never be used to
illuminate works of art or in public spaces because exposure can cause
(sometimes irreversible) damage to organic materials like paint, paper,
textiles, zoological and plant specimens, skin, eyes, etc.  (see
http://www.ftc.gov/bcp/conline/pubs/health/indootan.htm).

Long-wave UV is used by conservators to examine and photograph visible
fluorescence of coatings, pigments, and other materials comprising works of
art.  (Long-wave UV also is used to illuminate black-light posters in
novelty shops and teenagers' bedrooms.)  Some organic materials are
vulnerable to long-wave UV, so prolonged exposure to long-wave UV radiation
could cause discernable and sometimes irreversible damage.  For this reason,
conservators often recommend that exterior windows and fluorescent lights
should be covered with UV absorbing film or sleeves, respectively.

Long-wave UV radiation can cause eye discomfort for museum visitors,
especially when works are viewed in a darkened room because pupils dilate to
take in more light, or, as Meg pointed out, when visitors can look directly
at lamps.

The potential for damage to the paintings in question (and architectural
materials such as wall paint and carpet) would depend on the materials
comprising the paintings (and architectural materials), the wavelengths and
intensity of UV radiation emitted by the fixtures, proximity to the
fixtures, and exposure time.

Before ruling out the installation, consider that works of art are
vulnerable to many environmental variables (temperature, moisture, air
quality), housing and framing, vandalism, and inherent vice of component
materials.  With careful planning and testing it may be possible to design
an installation that balances short-term exhibition objectives against
long-term conservation goals and visitor comfort.

James Martin
Conservation Scientist
Orion Analytical, LLC
www.orionanalytical.com
413-458-0233

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