RE: Lithium palladium vs. "normal" palladium
Witho, Realize that what we are talking about is NOT 20 drops to 10 drops. It is a concentration issue. As I recall, early conversations with Jeffrey about this indicated that he was incorrectly applying % solutions and not working in molar solutions. The issue of FO being ill defined is also one of the driving issue behind Ware (I believe) because AFO can be made to be a specific molar solution with some certainty and not based on the individual batch and inert ingredients. Jeffrey did make some changes and I have not looked at his data or web site in a number of years so I don't know exactly where his information stands today. The point being is that the pt/pd process prints can be every bit as free as the gummers like to make things; well maybe not that free. We are all looking to make our prints in our own way. If someone wants to just keep buying mixed chems from B&S and make their prints with their directions, great for them. I haven't seen a paper that rivals the Ware investigation of platinum printing published in 1986. And Although I didn't see it until 1991 or 92, it confirmed many of the things up to that point that I had experienced as a printer over the last 10 years. Mix, blend and create! Just keep good notes : ) Eric Neilsen Photography 4101 Commerce Street Suite 9 Dallas, TX 75226 http://e.neilsen.home.att.net http://ericneilsenphotography.com Skype ejprinter > -----Original Message----- > From: Witho Worms [mailto:info@witho.nl] > Sent: Wednesday, January 17, 2007 2:46 AM > To: alt-photo-process-l@usask.ca > Subject: RE: Lithium palladium vs. "normal" palladium > > Hello Eric, > > It is good that you mention this. > > I did some reading again last week on the available chemistry publications > and there is something my eye fell on. Mike Ware states that the molar > ratio > of ammonia ferric oxalate to ammonia tetra chloro palladate is 2 :1 to > complete the reaction: > > Reaction 1 > > hv = 2[Fe(C2O4)3]3 => 2[Fe(C2O4)2]2- + C2O42- + 2CO2 > > Reaction 2 > > [PdCl4]2- + 2[Fe(C2O4)2]2 => Pd + 2[Fe(C2O4)2]- + 4Cl- > > > > But, if you read the manual of Jeffrey Matthias (which I took for a long > time as my guide) you will see that he uses a ratio of 1:1 > > (NH4)3Fe(C2O4)3.3H2O >exposure> Fe(C2O4)2 + 3(NH4) + 3H2O + 2CO2 > > 3Fe(C2O4)2 + 3Li2PdCl4 + 3(NH4) + 3H2O => > (NH4)3Fe(C2O4)3.3H2O + 2(FeCl3) + 6LiCl + 3Pd + 3(C2O4) > > And Jeffrey states also : 'Or other metallic salts could be substituted. > Every three sensitizer molecules will pair with three metallic double salt > molecules, a one-to-one ratio (1 metal salt for 1 sensitizer).' > > > This difference is substantial. I asked Mike Ware about it and Jeffrey > Matthias. Jeffrey replied me as follows : > > 'Remember that my work is based on empirical study, not theoretical. This > means that I am explaining things as they show themselves to behave > through > experimentation, not by the science of what they should or are doing. I > realized that I do not have the training and experience in ionic theory as > others, but I did have the time and patience to carefully run some > calibrated experiments. > > If the suggestion is that a print can be made with less metal than the > threshold, the result will be a weak print. Additional metal will just be > wasted. The statement: > "The correct stoicheiometry for trisoxalatoferrate(III) to > chloropalladate(II) in the sensitizer is indeed 2:1."(quoting Mike Ware in > an e mail to me) " is hard for me to understand. This is why I like to use > the compound's formulae rather than its name. I suspect that what is being > called 2:1 is the same as I have called 1:1. The bottom line is figuring > how > much of each substance to put into the solutions. What I call 1:1 is > consistent with historic formulas and works. If this is really 2:1 then so > be it. But, if it is suggested that twice or half as much sensitizer is to > be used or twice or half as much metal solution, I know that will produce > a > problem in the print.' > > Of course my suggestion to Jeffrey was not 'that a print can be made with > less metal than the threshold' but that you loose a lot of metal if the > ratio of the reacting compounds is not right. My suggestion is to run a > series of new tests with the different (2:1) ratio's. > > I have not calculated the B&S concentrations so I can't say from what > equations they start. Maybe Richard can tell us some more about it? > > Witho > > > > > > -----Oorspronkelijk bericht----- > Van: Eric Neilsen [mailto:ejnphoto@sbcglobal.net] > Verzonden: woensdag 17 januari 2007 0:52 > Aan: alt-photo-process-l@usask.ca > Onderwerp: RE: Lithium palladium vs. "normal" palladium > > > > > Eric, > > > > Thanks for the information; it's amazing how much there is to learn > about > > pt/pd printing. > > > > > > > 2 Moles of [Li, NH4, Na] Cl, to 1 mole of > > > PdCl2. How you decide to dilute it is up to you. > > > > How do different dilutions affect the print (color, dmax, etc.)? Just > out > > of curiosity, which dilutions do you (and others) use? > > > > The idea is to match the solution strength of the metal salts with that of > the Ferric; either AFO or FO. One can get bad Dmax or extra contrast > depending on which way the equation is set. > > > > > > > > How does one make there AFO, or FO is equally > > > important. The numbers are not etched in stone but the results nearly > > are > > > :) > > > > Not sure I'm following you here. Are you saying that there is an > "ideal" > > dilution of AFO/FO for a given dilution of pd, or are you simply saying > > that the AFO/FO dilution, whatever it may be, plays a significant role > in > > print results? > > > > Yes, equal to required needs. When you look at % solutions and matching > them > with molar solutions, that can be an easily lost battle unless you know > the > equivalent for each. What is a molar solution? A 1 molar solution is the > formula weight to make 1 liter of solution. Note I did not say add to 1 > liter different solution. You can see in Ware/Malde there is a .7M > solution > of both the ammonium based palladium and platinum salts. The AFO is mixed > at > 1.4M. And I see the mixing of solution / reactants like this, > > > If you are going to error on one side or the other you should error on the > side of too much of the catalyst. So for mixing your metal salts, the > extra > would come in the form of a little extra chloride cation _ the sodium, > ammonium, lithium, because with out it, the PdCl2 can not get into > solution. > And like wise, add extra AFO,FO because without it the precious solution > of > PT / PD will sit in the paper with no enough available Ferric to convert > it > into the new "black" state that forms your print. > > > I mix my solutions as close to .7 M as possible. The B&S solution are > quite > a bit less than .7 M. That is not to say that they are wrong, but it might > be a possible reason that many seem to require and extra coating to get > good > Dmax. Jeffrey Mathis has an extensive write up about optimizing the > solutions. I might not agree with everything there, the idea is a good > one. > Coat a variety of amounts, and see what gives you the best Dmax, color, > contrast. Find out what this ingredients really do, not just what someone > else has settled on. > > > Eric Neilsen Photography > 4101 Commerce Street > Suite 9 > Dallas, TX 75226 > http://e.neilsen.home.att.net > http://ericneilsenphotography.com > Skype ejprinter > >
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