Re: cyanotype question

Judy Siegel says in the "World Journal of Post Factory Photography" that
according to her experience, when one cuts exposure of cyanotype in the
middle and wait for several minutes, then shadow separation is better
(actually I first read that in the book of alt. processes by C. James - he
was transferring the very same information which was provided by Judy). I
guess your experience also confirms this phenomenon.

I'm exposing cyanotype in the same manner from the start so I don't know how
much is the difference (intermittent exposure and continuous exposure). All
I can say is that I'm pretty happy with the shadow separation I get (even if
I like better the prints when they're wet!)... BTW, my primary reason of
cutting exposure in two halves is to cool the tubes so they don't loose too
much UV output actually ;)

Regards,
Loris.

----- Original Message -----
From: "Joe Smigiel" <jsmigiel@kvcc.edu>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Thursday, September 02, 2004 12:56 AM
Subject: cyanotype question

> Today I ran an exposure test with the traditional cyanotype formula
> using a NuArc 21-1K mercury exposure unit. I got some unexpected
> results and am looking for a possible explanation from anyone familiar
> with the process.
>
> I first coated a sheet of Crane's PS8126 ecruwhite laid kid finish and
> dried it using a hair dryer w/o heat. I then cut the sheet into several
> parts and exposed the sheets simultaneously using three StoufferT2115
> step wedges. The NuArc was set to 250 units and one test strip removed
> after a 250 unit exposure. The second and third strips were given an
> additional 250 unit exposure then the second strip was removed from the
> exposure unit. The third strip was then given another 250 exposure so
> the three strips had total exposures of 250, 500, and 750 units,
> respectively.
>
> The sheets were then processed together given an initial 2 minute rinse
> in a 2% citric acid solution followed by a 10 minute wash and final 30
> second bath containing a few drops of hydrogen peroxide.
>
> When the strips dried, the exposure scales appear to be different, not
> just shifted between steps as exposure increased. (The strips did show
> a shift in position towards higher steps as exposure increased.) The 250
> strip had tones covering 1.63 density units, the 500 was 1.45, and the
> 750 was 1.31. The density figures are transmission densities of the
> step wedges as measured on an X-rite 301 densitometer and the printed
> densities were judged visually.
>
> So, it looks like the exposure range is decreasing as the total exposure
> increases. What's up with that?
>
> The solutions were several months old and since they were all processed
> together, the 250 and 500 unit exposures sat around while the last strip
> received the final 250 exposure. Another curious thing is that the
> solarized steps lost the solarized appearence as they sat in a paper
> safe while the final strip was exposed. This loss of solarization was
> also noticed last week when the humidity was very high. Why the loss of
> solarized tones as the strips waited for processing? And, is there some
> sort of intermittency effect with cyanotype?
>
> Any other ideas?
>
> Thanks for any info.
>
> Joe
>
Received on Wed Sep 1 16:25:22 2004