Re: test images: screw-in BLB UV box--1000 watt bulb?

Charles,

I don't think I can be of much help with that question as I generally
use the quartz lamp for gum printing and rely on the plateburner,
sunlight, and UV tubes for the rare cyanotypes I do. I have found the
UV tubes mysteriously fog gum emulsioins inexplicably and periodically,
though not all the time. That's why I started using the FEL lamp and I
have not had a fogged gum print since using that lamp or the
plateburner. My times for gum with an FEL lamp at ~6' to evenly cover
an 11x14 frame are around 6 minutes. This is about the same as the
times I used to give in the UV box for gum sensitized with ammonium
dichromate. Outdoors in the sun, the exposures would be about 1.5
minutes or less with the same materials. How that translates to
cyanotype printing is anyone's guess.

I find the exposures for cyanotypes outdoors in sunlight for my
negatives are usually about 7 minutes. The plate burner is longer,
perhaps double and UV tubes are probably more on the order of 3x-4x
sunlit exposures IIRC. My guess is that the FEL lamp exposures would be
between those of the UV box and the plateburner. I have never done a
formal test due to the infrequency that I print cyanotypes. When I do,
I like to print outdoors or if I'm using the plateburner, I'm burning
the print along with a step wedge and generally not paying attention to
the exposure times or units. When it solarizes the first step, I pull
and process it.

Heat may also be a problem with the FEL and cyanotypes. I suspect the
UV tubes should generate a lot less heat than the FEL or plate burner.

Sorry to be so vague, but it has been quite awhile since I've printed
any cyanotypes to speak of and my memory just ain't what it used to be.
(Personally I prefer to use the sun for cyanotypes since it does shorten
the times considerably.) I responded to the original question more to
indicate the specific UV source being used was insufficient especially
given the extreme exposure times (30 minutes to an hour with still
obvious underexposure). My guess is that any of the other UV sources
listed would considerably decrease the exposure times that the screw-in
UV bulbs were giving.

500W Quartz halogen lamp fixtures are available at most home improvement
superstores for around $10 US. You might give one of these cheap shop
fixtures a try before investing in something more expensive and see if a
quartz lamp provides a more useful spectrum than the long UV fluorescent
tubes for cyanotypes.

Perhaps someone else coud chime in here with more useful experiences
about alternative lamps for cyanotype printing.

Joe

>>> cryberg@comcast.net 07/12/05 11:51 AM >>>
Joe Smigiel--What kind of exposure do you get for cyanotypes with a 1000
watt bulb? I have a FEL-CP/77 but no socket for it. If you think I
might
get shorter exposure times than with my BLB tubes I could cobble a
socket
together. Otherwise, I understand that switiching to BL tubes will give
me
some help. Any suggestions?
Charles Portland OR
Received on Tue Jul 12 13:12:33 2005