[Alt-photo] Split exposure of cyanotype

John Isner john.isner at gmail.com
Mon Jan 29 15:10:33 UTC 2018

My split exposure print came out too light, not too dark.  I will re-try
the split exposure with the same negative to make sure I didn't mis-read
the exposure meter.

On Mon, Jan 29, 2018 at 12:04 AM, Loris Medici via Alt-photo-process-list <
alt-photo-process-list at lists.altphotolist.org> wrote:

> Hi John, looks like you're experiencing bronzing / solarization due to
> overexposure.
> Probably some dark reaction occurs between the first and second halves of
> the exposure, therefore you experience overexposure even if the total
> exposure time was equal to when you don't split exposure in two parts.
> If Dmax under the negative is gook / OK there's nothing to worry about,
> unless you also need borders with good Dmax.
> In order to open up shadow tones, I would fiddle with my curve instead of
> following this strange (to me) protocol...
> Regards,
> 2018-01-29 1:18 GMT+03:00 John Isner via Alt-photo-process-list <
> alt-photo-process-list at lists.altphotolist.org>:
> > I am relatively new at alt process in general and cyanotype in
> particular.
> > I'm using Ware's formula on Cranes Cover 90 lb Wove, exposing in the sun
> > with a UV integrator meter, and following all of the instructions that
> came
> > with the New Cyanotype kit.   I also carefully followed the steps in Ron
> > Reeder's chapter of Christina Anderson's Gum book to determine exposure
> > time for maximum black, the optimal negative density, and a curve for
> > correcting the midtones.
> >
> > On page 183 of Christopher James' 3rd edition, James suggests that you
> can
> > get improved shadow detail by suspending exposure midway through, keeping
> > the print in the dark for 15-30 minutes, then returning to UV for the
> > remainder of the exposure.  I found that this technique definitely
> improves
> > shadow detail.  James also says you should not "lose D-max integrity"
> but I
> > did not find this to be the case.  My overall print seemed lighter.  The
> > borders, where the paper is fully exposed to UV, are somewhat lighter
> than
> > the borders of a print made in one go.
> >
> > If a split exposure is supposed to retain D-max integrity, then I'm
> > guessing a longer exposure is needed.  If so, do I need to make a
> separate
> > determination of exposure time under split exposure conditions?  Or is
> > something else going on here?
> >
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