Re: Oxalic Acid + Potassium Chlorate


William Laven (wmlaven@platinotype.com)
Sun, 31 Jan 1999 11:52:21 -0800 (PST)


>Bill,
>If I may ask, why do you prefer Potassium Oxalate as your developer? Is
>it tone, contrast, color? Also, I recall reading--was it an article you
>wrote?--that you develop for five minutes. What advantages are there to
>developing for that length of time?
>

I like the look of PO's image -- not too warm, not too cool -- and it seems
a "deeper"image, like it sits in the paper more confidently than the image
does with Ammonium Citrate. (I use Arches Platine and 60% Pd, 40% Pd by the
way).

I also like the use of Sodium Dichromate as a contrast agent because its so
stable and it works with PO developer (and I thought with nothing else
until I read the recent post re:Ammonium Citrate). Why contrast agent in
the developer, not the sensitizer? Because then I can coat a printing
session's worth of paper in one quick sitting and also because FeOx#2 has
more grain than S.D. when used for contrast.

Yes, I do use a 5 minute developing time, much longer than "usual" I know.
But once I experimented with a couple of different images and watched them
closely in tray development at 1 minute, 2, 3, etc. There were some subtle
differences happening even past 2 1/2 minutes (ie more highlight detail)
which I wanted to preserve. Now, 5 minutes is much longer, but I develop in
a Jobo drum and just wanted to insure with that system (little developer,
lots of rotation) that the prints had a nice long bath in the developer.
Since you can't overdevelop a Pt/Pd print I decided to err long on the side
of caution. Besides, with a 5 minute development cycle, I can walk away
from the Jobo for a few minutes and start another print; it just makes my
work flow smoother. While I don't want to prolong the wet time of my prints
unnecessarily, I figured a couple extra minutes wouldn't hurt.

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