Selecting developer and clearing agent

Discussion in 'Alternative Processes' started by DrPhil, Aug 31, 2004.

  1. DrPhil

    DrPhil Member

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    I purchased Arentz's book on Pt/Pd print and am going to give it a try. Several folks have suggested that I purchase all the chemicals separately instead of as a kit. If I am to do this I need to decide what developer and clearing agent to use. B&S and Photographer's Formulary both include different chemicals in their kits. Thus, my question is what are the pros and cons of each choice.

    The B&S kit includes Ammonium Citrate as a developer. Formulary uses Potassium Oxalate. Arentz list them both as developers. Is one preferable to another? Is one considered tried and true? I understand the Potassium Oxalate is never discarded. Is this true for Ammonium Citrate?

    What about a clearing agent? B&S includes EDTA in their kit. Formulary uses Citric Acid. My understanding is that citric acid is stronger(more efficient?) than EDTA.

    My plan is to start with a tried and true setup as a baseline for experimentation. Crane's Platinotype seems to be the paper that is best suited for this. The coating solutions also seem straightforward. I am going to start with the A+B+C method prescribed in Arentz's book.

    Any suggestions would be greatly appreciated.
     
  2. Mateo

    Mateo Subscriber

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    I think the kits make sense for a first try and small quantities. You save allot of dough when you buy the metal solutions 100ml or 500ml at a time but that can be a hefty investment. I bought a 100ml bottle of #3 pt and it's going to last me a lifetime cause I prefer mostly palladium prints.

    As far as developers: I didn't like the citrates because of the way the highlights looked but I didn't give them much of a chance either. B+S will substitute Pot Ox in the kit if you ask.

    For Clearing I just use Hypo Clearing Agent so that I can support my local camera store. For me it clears faster that EDTA and almost as fast as citric acid with the benifit of leaving the prints slightly PH+. I don't know if that's voodoo but it make me feal better.

    You're gonna get addicted.
     
  3. Jorge

    Jorge Inactive

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    Ammonium citrate is a "slower" developer, you loose about one stop when using it compared to Pot oxalate. It gives you a more neutral tone than Pot oxalate and like Mateo said, prints developed in it lack the "glow" a well made pt/pd print can exhibit. I like Pot Oxalate as the developer much better than ammoium citrate.

    Like Mateo I use HCA. It works and it is cheap, much cheaper than EDTA or citric acid. Anything that dissolves Iron will work fine, I have heard of some people using sprite as CA. the phosphric acid in it is good enough to clear a print.

    While the kits are convenient, if you plan to stick with it, buy the bulk materials. There is nothing more maddening than experimenting and running out of solutions. Michael at Artcraft chemicals is selling the Pd at $12/gram and the Pt at $20/gr. If anything you can go with the Pd only and experiment with that before you do the pt/pd print.

    With exception of Arentz, I dont know anybody that likes Platinotype better than other papers. Arches Platine, COT320, Even Socorro with an Oxalic acid prebath are far better IMO than Platinotype. I would say instead of ordering a bunch of one paper, order about 2 or 3 sheets of each and try them all, see what works best for you.

    If you can, get the Richeson 9010 brush, it will save you a whole bunch of money on coating. Far better than the hake brushes or the puddle pusher.

    Good luck, and welcome to the club....:smile:
     
  4. sanking

    sanking Member

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    I don't know about the speed of ammonium citrate but there is very little if any difference in printing speed between sodium citrate (which I believe is a lot less expensive than ammonium citrate) and potassium oxalate and if you use them both at room temperature the tone and warmth is about the same. If you use the developers at 100º F. potassium oxalate will give more warmth (more brownish look) than sodium citrate but I prefer more neutral tones and tend to use citrate more than oxalate.

    As for clearning agent I have found citric acid to be more effective than EDTA, and at $1.65 per pound in pails of 30 lbs from the Chemistry Store it is very inexpensive. Hard to believe that the Kodak Hypo Clearing Agent could be less expensive than that. You can also get sodium citrate at the Chemistry Store.

    I prefer the Na2 methoid of contrast control over the A-B-C method. Both will give good results with negatives of normal contrast for pt./pd. but the Na2 method gives more flexibility for contrast control.

    As for papers one of the very best is Cot-320 by Bergger. I use it right out of the package and get excellent Dmax and very good sharpness.

    Sandy
     
  5. sanking

    sanking Member

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    After further testing over the past several days of both kalltype and palladium, using ammonium citrate, sodium citrate and potassium oxalate developers, I have concluded that what I wrote above is not correct for palladium printing. In fact, these tests confirm that potassium oxalate can give up to one full stop in printing speed over sodium citrate. Since this is consistent with Jorge’s observations for ammonium citrate it would appear that the two citrates have about the same printing speed. Potassium oxalate also give slightly more Dmax in the above test, but color and tonal range was about the same with both developers, when adjusted for speed. Processing was done with the developers at room temperature of about 72º F.

    I could not make a direct comparison in printing speed for kallitype with the two developers because potassium oxalate caused a very high level of staining that made it useless for kallitype. At least that was the case in my tests, though I should mention that the potassium oxalate solution used to develop the kallitype was previously used as a palladium developer and contamination may have contributed to the stain.

    In comparing kallitype developed in a 25% sodium citrate developer with palladium developed in a 25% potassium oxalate developer kallitype was faster by about one full stop.

    For those interested in BTZS type plotting, these were my results.

    1. Palladium developed in 25% potassium oxalate.
    Exposure Scale = 1.55
    Sp. Pt. = 1.9
    Dmax = 1.48
    (For a 4X5 print, 6 drops FO +6 drops PC + 2 drops of 2.5% Na2.)

    2. Palladium developed in 25% sodium citrate
    Exposure Scale = 1.35
    Sp. Pt. = 1.6
    Dmax = 1.42
    (For a 4X5 print, 6 drops FO +6 drops PC + 2 drops of 2.5% Na2.)

    3. Palladium toned Kallitype developed in 25% sodium citrate
    Exposure Scale = 1.66
    Sp. Pt. = 2.2
    Dmax = 1.52
    (For a 4X5 print, 6 drops FO +6 drops SN with development in a 25% sodium citrate solution, 1 ml of 5% potassum dichromate per liter.)

    Just for the record the above tests were done on Stonhenge paper that had received a 1% soak in oxalic acid. With this paper the oxalic acid soak increased Dmax by almost log 0.20 with both kallitype and palladium.

    Sandy King
     
    Last edited by a moderator: Sep 15, 2004
  6. cjarvis

    cjarvis Member

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    Clearing agents:

    In my experience I CAN NOT get Cranes Platinotype to clear in EDTA. I have no idea why. I use citric acid. HCA may work just as well, but in bulk (2.5kg) citric acid is cheaper.

    Also, Jorge said, "anything that dissolves iron" will work. I know as a chemist he meant, "anything that chelates iron" will work.

    Obviously some chelating agents must be better than others with certain papers. Hydrochloric acid works well. You can buy it from your local swimming pool store as muriatic acid.
     
  7. kudzma

    kudzma Member

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    I’ll chime in with my observations. I much prefer the look of Pd/Pt prints developed with hot (100F) potassium oxalate. I’ve used citrates (ammonium, Na and K) and the prints lack a subtle “sparkle” that I get with warm or hot potassium oxalate.

    As for clearing, this can be very paper specific. For example, “Cranes 90lb Wove Cover Stock” which is very likely exactly what B&S sells as Platinotype clears very well in citric acid/warm water. This Cranes paper has undergone obvious changes in the last few years, but despite some experienced Pt printers disdain for this paper it is still a good paper IMHO.

    Whatman 130lb hot press watercolor paper (a real favorite of mine) clears very poorly (slow) in citric acid. Interestingly, it clears very rapidly in EDTA (Na2)/hot water. Note that in this case, having the disodium form of EDTA for clearing is important. Disodium EDTA is acidic, while the more easily available tetrasodium EDTA is neutral. EDTA sold as just “EDTA” is almost always tetrasodium EDTA, which in my experience is not as good for clearing.

    Of course someone will now post a completely different opinions or preferences re: papers, clearing, developers, etc. You have to experiment to find what works for you, your papers and process.
     
  8. philsweeney

    philsweeney Member

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    Sandy,

    For 7 x 17 I have been using one tray and wonder how many times you recommend using the 3% citric acid?

    phil
     
  9. sanking

    sanking Member

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