Ms. Maltby,
Perhaps you can help me with a question that has been bugging me lately.
Why do we measure UV as micro watts per lumen in museums?  Is it just
because the first affordable UV meters measured in those units?  I have
noticed that the price of UV meters has come down enormously in the last
few years, but the price of meters that measure mW/lumen is still very
high.  The mW/lumen measurement seems strange to me because you can get
an "acceptable" measurement simply by increasing the amount of visible
light (which would, of course, be damaging to most museum objects).  We
have standards for visible light measurements--why don't we have
standards for the direct amount of UV rather than a proportion of UV to
visible light?

Thanks for your help,
John

-----Original Message-----
From: Museum discussion list [mailto:[log in to unmask]] On
Behalf Of Susan L. Maltby
Sent: Wednesday, July 20, 2005 7:53 AM
To: [log in to unmask]
Subject: UV Meter

Regarding the request for UV meters.  It is important to look for a
meter that 
gives the results in micro watts per lumen.  This is how we measure UV
in 
museums.  There are a number of UV meters out there that will measure UV
but 
not give you the answer in this form.  In order to get the results in 
microwatts/lumen you need to combine the results with a visible light
meter - 
too much math for me & likely most folks :).  Elsec makes a very nice
meter 
which measures UV, visible light, RH & temperature.

Susan Maltby, Conservator
Maltby & Associates Inc.
Adjunct Professor, Museum Studies Programme
University of Toronto

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