RE: Potassium Oxalate developer for Platinum printing

Cor, Your developer will hold onto a portion of your coated area that was
exposed and not part of the print. This coated and very slightly excited
area will become part of that 500ml; which seems really skimpy to me by the
way. There are also buffers in the papers that can adversely effect your
developer. While you may only need 500ml to cover your paper, I'd advise you
to use a larger amount as a stock solution. If the cost of Potassium Oxalate
powder is high in your area, I would make it from Potassium Carbonate and
Oxalic acid. Pour out the amount need to develop your print, and after pour
it back.
 
You can also use Oxalic acid to keep your developer on the acid side of
life. You may also find that exposing your developer to UV light and
letting it sit, will allow you to remove the excess metals from your
developer. The greenish quality is not a problem. Single shot eliminates the
chance of fog due to removed components from previous prints, but I don't
find it necessary.

You can use a lower concentration of Pot ox but you run the risk of graining
up your prints. You will also need slightly more exposure.

I have only tried brush development a few times, but I would look into a
good even pour ,just like for coating the sensitizer, and a quick even
dispersal of the coating, perhaps even by using a rod.

Eric

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
 
> -----Original Message-----
> From: Breukel, C. (HKG) [mailto:C.Breukel@lumc.nl]
> Sent: Monday, April 24, 2006 5:52 AM
> To: alt-photo-process-l@usask.ca
> Subject: Potassium Oxalate developer for Platinum printing
>
> (maybe you'll see this message for the second time, I did not see it
> appear..)
>
> Hi,
>
>
> I have been using a 25% solution of Potassium Oxalate as my developer
> for Platinum printing (no Palladium added), and to my surprise this
> developer went "off" rather quikly. That is: in the 500ml I started with
> I could process only 5-7 8*10 images (did not keep exact count). My last
> print showed veiled highlights, which did not want to clear, and the
> PotOx solution is now very murky with a greenish brown strong colour.
>
> I looked into dome books as well as in the archives, and the things I
> find are contradicting (no surprise I guess). Crawford (and Farber who I
> think quotes Crawford) claims that the developer keeps indefinitely, and
> has only be toped up with fresh developer to make up for the loss. It
> actually gets better when it's more used. James states about the same,
> although he says that there is an end to the live of the developer.
> Jeffrey Mathias advices to use the developer single shot, reusing will
> cause fog..
>
> Single shot seems a bit wasteful, as well environmental unfriendly with
> this toxic chemical, OTOH 6 8*10 prints with half a litre isn't exactly
> economical either, plus the ruining of the last print.
>
> Can one use a lower concentration of PotOX, develop longer and discard
> it afterwards?
>
> I did try brush development with glycerol: PotOx 1:1, but I wasn't very
> successful with that, got a lot of developer lines, will brush
> development also work with FO, I have only read about it connection with
> AFO.
>
> Comments or suggestions/
>
> Thanks!
>
>
> Cor
Received on Mon Apr 24 19:35:03 2006