However a few comments seem to be in order about what kind of bulbs you
can coat emulsion by, which was the origin of this thread. I doubt many of
us have halogen in the workroom (?). In fact my own experience of halogen
around the house (other people's houses) is that it's largely a marketing
device -- for 200% more money you can get 15% more light in a bulb that
burns so hot it vaporizes plaster. And I, tin-eyed creature that I am,
have never discerned the "beauty" of halogen light.
However, there's a very easy way to test your set-up for sure, and not
have to depend on the "experts" in books who have (I bet) not made the
tests themselves, but simply copied what they have read elsewhere in a
chain of spurious "authority" back to Copernicus. (And the fancier the
manual, the more alt-politically correct it will be, on the principle that
heaven forbid you get fog and sue the publisher.)
Here are the tests I did at various times for cyanotype, VDB and gum.
Using the same everything I coated 4 strips of paper, one by feel in
complete darkness, one by the "safelight" du jour and two by my usual
available roomlight, which is 15 feet from a large north window by day,
ceiling 100-watt incandescent bulb and two 8-foot ceiling fluorescents
near the windows at night (or surely more UV light than one of those itty
bitty halogen bulbs).
All strips were dried in the dark except for one of the roomlight coated
ones which was left out on the table in the roomlight to dry.
After 1/2 hour all were exposed uniformly under 21-steps and developed
identically. Differences that I could detect were minimal and could have
been due to differences between individual step tablets or in the hand
coating -- except for the roomlight-dried gum, which had more dichromate
stain. In some cases, BTW, the roomlight strip seemed to have a slightly
longer scale or deeper tones.
I'll add that my testing and "reading" skills have improved in the years
since I did these tests, so I might detect more difference today -- or
less. Whatever, this is a non-issue for me. Frankly, I suspect it is a
device to keep alt-printers oppressed by making them think they have to do
it in the darkroom.
> Nevertheless, I would not want any
> of my work displayed under halogen lights for very long unless is was
> platinium or black i.e. monochrome gum. Cyanotype and Kallitype would
> probably be unhappy under these lights. Maybe someone on the list has
> some technical info on these halogen bulbs.
>
> Bob Schramm
And of course we must bear in mind the difference between perhaps one
minute for the coating procedure, where the issue is fogging, and hour
after hour for a print displayed on the wall, where the issue is fading.
Cheers,
Judy