I agree with Keith here. Eliminating the water bath/rinse after the developer and prior to the first clearing solved a lot of clearing problems for me.
Originally Posted by jkschreiber
Not using a water bath after developer also applies to kallitype printing in my experience as well.
And yes as Matt mentions, 5 min development also helps a lot.
Please forgive if that's asking the obvious (especially for a seasoned printer - if you're one): Is your sensitizer (Ferric Oxalate) fresh?
I use Arches Platine paper for my Pd/pt prints for more than ten years now.
Most of the time I use pot.oxalate as developer for 2 minutes and it's enough. Not less but longer will not really help.
Just two things to get it cleared after that: the first water bath MUST be on the acidic side.
To be sure of that I always put one tea spoon of citric acid in a liter of water. Two baths for one minute (1/2 liter each time).
Arches Platine must be cleared after that with a working solution of HCA from Kodak or it's equivalent Sodium Sulfite 20g/liter. 2x 5 minutes.
Wash for 15 minutes and your print will be cleared.
I guess I am old school. I use hydrochloric acid and it works fine and is cheap. I do let the print sit in the potas Oxalate for 2 minutes or more.
Dr. Mike Ware reports his microscopic examination of paper cleared with hydrochloric acid is detrimental to the fibers of the paper.
Originally Posted by dpurdy
Something to keep in mind.
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Originally Posted by Loris Medici
I'm confused now, because my question was to Luca the O.P.?
Originally Posted by donbga
My understanding was that it depends -> since he also suggest using very weak HCl (or nitric acid) - something like 1% and such - in cyanotype processing. (Or maybe it was in some other context, but I'm sure that he actually suggests that...)
Of course, for pt/pd the suggested (in the literature) strengths of mineral acid clearing baths are usually something like 5%, considerably stronger than 1%...
Since citric acid works so well for me, I never had to consider HCl as a clearing bath. But I use HCl at that strenght (5%) often for acidification of Fabriano Artistico; a heavily buffered paper - if you accept that justification...
Originally Posted by donbga
Last edited by Loris Medici; 12-24-2009 at 03:12 PM. Click to view previous post history.
Reason: Typo correction...
All of these suggestions are good. The bottom line is to avoid any contact with a solution that has a pH over 7 before the unused ferric has been cleared out. In my area, this means a water rinse after the developer is out of the question. For me, a disodium EDTA bath followed by two HCA baths will clear most papers. For some really stubborn papers, i keep a bottle of already dilute phosphoric acid (note: has some nasty fumes) that I can whip out for the last bath if necessary. One useful tip is to view the paper with a light shining through it from the back after that last bath. Examine the highlight areas closely for any hint of a yellow tone. If you see any, you haven't adequately cleared the paper, and may need a longer soak or a different bath such as the phosphoric acid I mentioned earlier. Dilute muriatic acid (HCl) will work as well, but is noxious to breath (much worse than phosphoric) and will corrode any metal in your sink area in no time. I stay away from it because it because of its nastier side effects.
To Loris: yes my ferric oxalate is absolutely fresh, just arrived and mixed. All my chems are fine for I have tried with some Cranes Crest paper scraps and the prints come out perfect.
I had to go away for a couple days for Christmas, now I am about to experiment with all these kind suggestions and will report back the results. Thanks!!