> I spent last week at a BTZS workshop with Phil Davis who I'm sure
> some of you know or know of. Besides myself, there were 2 other pt/pd
> Phil said that he had made a bank
> of fluorescent tubes using regular cool white bulbs which were
> comparable in printing time to black light bulbs.
>
Hi Keith and all,
Having survived a heartwarming family thanksgiving, I'm ready for
anything -- even (dare I say it?) contradicting Phil Davis. Here are my
findings with electricity from NY's Con Edison:
"Regular" cool white fluorescents took 50 minutes to make a paler tone
than so-called "black light" fluorescents made in 10 minutes -- in the SAME
fixture.
The "black light" fluorescents (labelled "BL") peak at about 360
nanometers and cost from $10 to $15 each in 20-watt, 24-inch lengths. Lit,
they show a pale pink or blue light; unlit, they look much like "regular"
fluorescents.
The "Black light blue" fluorescents (labelled "BLB") peak at about the
same 360 nm, but are covered with a dark blue glass that blocks all but
certain UV light. Lit, they show an eerie purplish glow. They have uses in
industry (and discos) but are pointless for our purposes since the glass
is expensive, the bulbs cost about $30 each, and the light is less.
(Tested against BL bulbs, the BLBs are about 20% slower.)
My tests were made using cyanotype and it is not beyond the realm of
possibility that other processes would respond differently. However, the
charts I've seen suggest ANY equivalence between BL bulbs & "regular"
fluorescents would be highly unlikely....
Judy