dMax of 1.30 is not great but acceptable in my world, clearly there is more experimentation that needs to go on to start fine tuning, loris do you do any pre-treatment to FAEW before applying the emulsion?
Hi again Stan,
No special treatment other than the addition of 1 or 2 drops of glycerol (humectant) per ml to the coating solution, when I work <=50% relative humidity. With pop Pd, you need a certain amount of humidity in the paper for best results...
I tried acidification with sulfamic acid on Zerkall book paper and did some Pd prints. This paper is only slightly buffered (close to neutral pH). Treatment with citric acid improves especially the mid tone but with sulfamic acid (0.5 M) pretreatment I got grainy highlights and mids (slightly better than untreated paper) but good dMax. Also the paper surface got softer so I was wondering if sulfamic acid is not only removing calcium carbonate but also interacting with the paper sizing.
If the paper has gelatin sizing, due to considerable duration of acid and water washes it is possible imo that the gelatin sizing might be diminished or even removed completely.
Afaik, many water color papers now used AKD sizing, and it is impossible to effect AKD sizing with acid treatment, but I have no experience with Zerkall papers. I have no idea on its sizing.
I tested Hahnemühle's gravure paper with argyrotype, its surface was very delicate and the print easily abraded, because it has no sizing.
I added ilfotol to sensitizers (argyrotype, new cyanotype, VDB) with SA treated papers, may be it can help with grainy highlights. I have no experience with Pd, so don't take my word for it.
I can report one of my favorite and more difficult papers to print on now is predictable, easy coating and a great black. Rives BFK a paper from the printmaking world as opposed to the watercolor world. I have only experimented with the 175 gsm but I have some 300 gsm coming in. But very happy that as far I can see at this point it will probably jump to the start of preferred papers for Pt/Pd. This was from using the 20/20 10% sulfamic technique. Thank you for sharing your testing.
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Originally Posted by sklimek
It is great to hear from you again and it is good news for Pt/Pd enthusiasts (unlucky me, I can't afford pt/pd yet ).
Well, I will note that paper down for myself, there can be no doubt about the quality of the paper imo. It is great to have the contribution of such master printer.
I will soon (a few days, need to do some tests) include some shortcomings of the SA itself, it is not concerning the de-alkalizing procedure.
It is likely that after treating 20-25 full sheets(56x76cm), the reactions times would get longer (depends on the paper buffer).
It is not about the capacity of the acid, or the de-alkalizing procedure, but the nature of sulfamic acid.
I will elaborate on the subject later.
A short update about sulfamic acid treated Zerkall book paper: I did some cyanotypes (traditional and Mike Ware's process) and I got very smooth mids (in contrast to palladiotypes) and good Dmax.
That is very good to hear. You might consider using 1M SA, I mentioned that I would post some extra info on SA but I can't do it at the moment. I hope to make it in a week's time.
Trouble in paradise?
I was supposed to make an update on the issue of de-alkalizing papers with sulfamic acid but I was not able to gather my mind and write something. Things were and still are a bit hectic in Turkey so sorry for the delay.
As I have passed halfway the capacity of 1M 3lt (%10) of SA solution (3 months old), I have realized that the time required to remove the chalk from the papers almost increased %50. I was worried if I made a mistake calculating the capacity of the solution. A quick inquiry lead me to this information: “aqueous solutions of sulfamic acid are much slower in action and require heating to remove scale. The sulfamic acid solution is heated to a temperature in the range of 54 to 71°C (130 to 160 °F) to obtain the same fast cleaning time that is achieved by using hydrochloric acid at room temperature.”
Apparently the slow acting nature of SA might be the reason why SA treated papers prints better than the papers treated with equally acidic HCl solution. Probably due to slow acting of SA, the fibers of the paper are less damaged by acid.
Anyway, due to its slow reaction speed at room temperature using halfway exhausted SA solution the time required to de-alkalize paper increases more than expexted imo. As always, the actual time depends on the paper and the buffer. Yet, I have not observed any irregularities or loss of d-max with the papers treated for 30mins in SA. And, as the information I have found suggests heated SA solutions react faster, but washing the papers in hot solutions is not a good idea. (30-35C might be acceptable but maintaining the temperature is also another issue)
At any rate, I wanted to point out that the time required to clear the papers’ buffer might increase as the SA solution gets used, but that is nothing to worry about. The previous molar calculations about the capacity are correct (1M 3lt solution should safely de-alkalize 45 full sheets), but the time required would increase gradually.
It is normal actually, as the capacity of the acid decreases the reaction time would increase gradually, but the increase in time was a bit dramatic than I expected. That is why I felt the need to clarify.
I have de-alkalized 28 full sheets so far with the solution I have prepared approximately 3 months ago and it is still working. If time is an issue you should always dump the old solution and prepare a new considering the low cost and effectiveness of sulfamic acid.
Be sure to thoroughly wash your treated papers before using. I washed the paper for about 15 minutes (rising stonehenge) and got an ugly, grainy blob of an image. I let the paper wash for an hour and the print was much much better. If I were to go the SA route, I will have to adjust my digi negs profile.