fluorescent afterglow

["Stan Patz" <skp113@xxxxxxxxxxx>]

To Ken, Andy and the group,

Back in March we had a brief exchange about the fogging potential of 
fluorescent lights in the darkroom. I conceded that the afterglow may be a 
problem, but it had not affected any of my film in the last 25 years.

Anyhow, I decided to run some tests and see if I was harming my film.  In 
the last few months, I  tested 4x5 TMX sheets (100 EI) whenever I had some 
empty slots in my processing reel. The results surprised me.

Even though I could still see a faint glow in the 8' cool white tubes, film 
left on my counter 5 or 6 feet from the tubes were unaffected - after five 
minutes! I then started pre-exposing the film to make it more sensitive. No 
fog. Then I hung film ON THE TUBE for five minutes, and still got nothing.  
It was weird, because I could almost see the tube in the dark, and when I 
pulled the tape off the glass, there was a pronounce static(?) flash.

Today,  I tested a sheet of TMY (400 EI), pre-exposed, and I hung it on the 
fluorescent fixture next to the tube for about seven minutes. Success! I got 
a little bit of density in the clear areas.

Conclusion? Here in New York City, in my darkroom, the afterglow from 
fluorescents pose no practical fogging threat to film.


Stan Patz   NYC


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