Clearing time is only a minute.
Everybody has different times. Sandy King says 2 minutes in each of two citric acid baths on the Unblinking Eye site, but 5 minutes in each on the Alternative Photography site. I gather Don Nelson's new kallitype book, just out, has a different scheme that requires EDTA, though he would not say why when asked in another thread here. (He also said that he had not printed kallitypes for over a decade, so YMMV.) FWIW I use citric acid because I find EDTA tends to wash out highlight detail, but I do use two citric acid baths and I clear them for maybe five minutes altogether.
I cannot say my process is right, or that yours is not. I find that a lot of people state their process as gospel but then cannot provide support for what they think is correct. I figure something like 5 minutes total in two citric baths is good enough. A minute seems short but I am not the one to say.
But when pressed to explain, he did not reply.
While he doesn't offer a chemical explanation, he does mention personal experience and notable differences in yellowing.Ferric yellowing of paper is most noticeable if you mask the areas outside the print area and is almost unnoticeable if you all brush marks on your prints. It seems to occur after long periods of time and isn't evident even weeks after drying a print -- it takes years. I have kallitypes made in 1992 that were cleared in just citric acid, showing noticeable yellowing in these areas. I switched to clearing Kallitype with first bath Disodium EDTA after attending a Dick Arentz NA2 Platinum/Palladium workshop in 1995. I see no long term yellowing in those prints in the masked areas around the image.
While he doesn't offer a chemical explanation, he does mention personal experience and notable differences in yellowing.
I respect the experiences of others. I would like more information to be able to put it into a context, so I can decide whether to alter my own processes. Ipse dixits aren't worth a whole lot.
Update:
IT WORKS!
I am using a JOBO Multitank 2551 on a Chromega roller base to clear kallitypes— the paper size is 8x8 and would easily fit an 8x10. Pour in 500ml of citric acid, flip the switch, and the print is clear 5-7 minutes later.
Update:
IT WORKS!
I am using a JOBO Multitank 2551 on a Chromega roller base to clear kallitypes— the paper size is 8x8 and would easily fit an 8x10. Pour in 500ml of citric acid, flip the switch, and the print is clear 5-7 minutes later.
Yeah, I know the feeling. It turns out that literally every alt. process you start to investigate is 'documented' in this way, with wholly or partially incomplete empirical data that's difficult or impossible to verify.
Good - I always seemed to crease the paper trying to put a wet print back in a drum. Probably just me. I’m not the most dexterous. I can see the advantage of constant agitation for 5 minutes.
Most likely the times could be shortened as the agitation would be much more vigorous.
I started out trying this out to speed up my printing for a print exchange. I figured I could clear one print while exposing and developing the next print. In practical terms, that means I am leaving the print in the rotary clearing bath (citric acid) for maybe 7-8 minutes. Using citric acid, the longer time in the rotary clearing bath does not appear to degrade the print. And perhaps the longer time in a more vigorous bath will improve the archival performance of citric acid as the clearing bath.
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