>A home I use a bank of 6 FL bulbs as a light source. Last semester I
>constructed a bank of 8 bulbs (same bulbs, same manufacturer, same
wattage, etc) for use by my students.
[snip]
>exposure times I said that I had been using exposures of 30-90 minutes at
home
>but to run some test strips. To my surprise the test strips and the
subsequent
>prints they made suggested that exposure times of 1/2 to 2 minutes were
>correct.
[snip]
Here's something you might try: get an accurate voltmeter for AC (there is
one that goes from 100 to 130 volts which would be ideal) and check the
voltages at your home and at school. I'll be willing to wager there is a 5
to 10 volt difference in the locations. Fluorescents (like incandescents)
go into the blue/violet range to a greater degree when run at a higher
voltage. (Are you old enough to remember Photofloods? These were 64 volt
bulbs overdriven at 120 volts to provide highly actinic light. Didn't last
long, but were great while they lasted!)
My voltage here normally varies from 115 to 125 volts; I have a constant
voltage transformer on my enlarger that provides 120 volts so results can
be consistent. If your school voltage is 125 volts (very possible during
periods of low overall usage) and your home voltage is 115 volts, this
could make the difference in exposure time. You have other variables, too,
so you might check them out, one by one. But I think "the voltage done it!"
Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net