Re: Is light unit after-glow a problem?
wmlaven@well.com
Sun, 1 Dec 1996 16:56:48 -0800 (PST)
>I'm going to put on my physicist hat and say that "after-glow" is
>not harmful. What you are observing is phospheresence. The light is
>coming from the coating on the inside of the tube. Very little if any
>UV comes from the coating. The UV comes from the arc itself. BTW you can
>see this effect right after you switch off your TV in a dark room. Also
>some darkroom timers have phospherescent markings.
>Speaking of UV. One of my colleagues in the Art Department is using a
>carbon arc for photo silkscreen. I told him I thought is was dangerous
>both in terms of the UV leakage and the gas produced. It is an open arc
>enclosed on the side and back by a tin box which is open in front. There
>is no ventilation. Is anyone out there using one of these things?
>
>Bob Schramm
For a year or so I used an open carbon-arc lamp which had to be manually
adjusted (ie I had to look at the arc ocasionally and as it diminished had
to turn a knob to move the carbon rods closer together). I invited a friend
of mine over who was interested in Pt/Pd printing and also happened to be a
doctor. After he reeled off a laundry list of how the unit was hurting me
-- lung problems from inhaling glass and particulate matter, serious risk
to retinas from looking at UV source, etc -- I got rid of it and built my
first of many florescent UV boxes. They belong in museums, not darkrooms.
Bill