Re: UV lights for gum

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From: Sandy King (sanking@hubcap.clemson.edu)
Date: 04/25/00-11:01:22 AM Z


A question for those who use the sun as UV light. Do you expose with
the contact frame in full sunlight or in the shadow? Does it make a
difference in terms of apparent sharpness?

Sandy King

>Very true, Les, which is why I would suggest a comparison of the four
>sources by the same person (probably impossible unless he/she is very rich
>and possesses all light sources!) with the same substances at the same time;
>that way you'd at least eliminate some of the variables that would give
>false reads of the experiment, e.g. gum mixture, paper, person's negative,
>humidity in the environment, pigment type, on and on. I have always
>preferred the sun for two reasons only: I usually fly by the seat of my
>pants in photography and prefer running inside and outside (with a cup of
>coffee in hand) in an intuitive panic to expose my prints; and, I don't
>possess another light source! The problem being, as you have pointed out,
>that I get great sun in MT all the time but the angle of rays and strength
>of the sun is so continuously changing that there is a time period I cannot
>print, basically about november through feb. And, of course, how many of us
>living in big cities actually have easily available sun? Therefore, I would
>love to buy a light unit but now am in a quandary as to which one is best
>for gum.
>Chris
>
>
> > The there's the variablity of the sun itself. Montana sun in June is
>different
> > from Montana sun in December which is still different than the sun that
>hits
> > the ground in LA. any time of the year. So anybody's empirical tests will
>only
> > be good for the surrounding area, will it not?
> >
> >
> > Les
> >
> > "Christina Z. Anderson" wrote:
> >
> > > I am very interested in this strain: I have always printed my gums in
>(lo
> > > and behold) sunlight and they have worked out fine, and have heard that
> > > artificial light sources in general produce duller images, but thought I
> > > would buy an Edwards Lightbox in the near future because Montana's
>sunlight
> > > is pretty indirect in dead winter. So you are saying that fluorescent
>(sp)
> > > bulbs are duller and lower in contrast than two other artificial light
> > > sources? How about the three artificial in relation to sunlight? It
>seems
> > > we are talking four sources here: fluorescent, quartz halogen, and
>metal
> > > halide....vs. sun, of course. So which is best? Or is this anecdotal?
>In
> > > other words, wouldn't you have to test the same neg 4 times to really
>get a
> > > good judge of the issue, for perhaps it's the neg that is the problem
>(or
> > > the gum mixture, etc)? Is there visual proof? Please excuse the
>snipping
> > > condensation of two messages below...
> > > Chris
> > >
> > > > As a part of that first online class (kudos, Dick...great idea and
> > > > > experience) I was a victim of the fluorescent failure. I'd used an
> > > > > Edwards Engineering box successfully for some prints in V.D,
>cyanotype
> > > > > (original and Ware formulas), platinum, and gum. Of all of these gum
>was
> > > > > the worst.
> > > > > During the Livick class, my test negative just died in all tests and
> > > > > soon it became apparent the difference was the light source.
>Subsequent
> > > > > testing by another classmate, Joe Smeigel, with quartz halogen lamps
> > > > > produced promising results, but the metal halide lamps were clear
> > > > > winners.
> > >
> > > > As ever, generalisations about gum printing seem to beg for
>contradiction.
> > > > Or let me say again that recently when my NuArc died, I went back to
>the
> > > > BL bulbs and found they printed much better, easier. My thought is
>that
> > > > they print gum somewhat flatter -- ie, longer scale -- which could be
>why.
> > > > (Tho when I had the reflective foil under the fluorescent bulbs they
> > > > printed worse, purely fuzzified.)
> > > >
> > > > >
> > > >
> > > >
> >
> >


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