Fluorescent lighting for exhibitions

It has been suggested that in order to give an industrial look to an
upcoming exhibition of works of art and documents on paper, we
suspend banks of fluorescent light from the ceilings of our
galleries rather than using the existing incandescent lighting
system.  We have, on one occasion in the past, used fluorescent
light in a small exhibition of black and white photographs.  In that
case we protected the works from UV light by using fluorescent tubes
with a fairly low UV output and by putting UV filter sleeves on the
tubes and UV filtering plexi over the objects.  (This may have been
overkill.)  We reduced visible light levels using a dimmer switch
and a double layer of neutral filters.  Still, visible light levels
were higher than usual (about 150 to 200 lux) during that
exhibition.  This was acceptable, however, since it was a short
exhibition of light-stable modern silver gelatine photographs which
were in good condition.

For the upcoming exhibition, however, we must reduce light levels to
50 lux. According to my previous research, we can only reduce light
levels emitted by the fluorescent tubes by up to 40% using a dimmer
switch--if we attempt to lower the levels any further the lights
will flicker.  And, based on the experience of our previous
exhibition, use of a dimmer switch plus a double layer of neutral
filtering on the UV tubes will NOT be nearly enough to reduce the
light levels to 50 lux unless we can find UV tubes that are very low
in intensity.

Do such low intensity UV lights exist?  Has anyone else tackled this
problem - lighting a gallery at only 50 lux using banks of
fluorescent lights?  If so, could you please tell me what  type of
fluorescent fixtures you used and how you succeeded in reducing
light levels sufficiently.  Can we get light levels down to 50 lux
using low intensity tubes, dimmers, neutral filters, deflectors and
diffusers?  The distance from the lights to the objects will vary
since in some galleries works of art will be hung from floor to
ceiling--hence it may be very difficult to get even lighting, as
well.

I would appreciate receiving information, ideas and anecdotes on the
use of fluorescent lights in exhibitions.

Karen Potje
Chef du Service de la conservation/restauration
Head, Conservation/Preservation
Centre Canadien d'Architecture
1920, rue Baile
Montreal, Quebec, H3H 2S6


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                  Conservation DistList Instance 17:2
                  Distributed: Thursday, June 19, 2003
                        Message Id: cdl-17-2-020
                                  ***