Re: cyanotype question


Adam Kimball (akimball@finebrand.com)
Tue, 29 Jun 1999 00:30:42 -0700


OK, Judy caught me. I exchanged a few mails with Mike last week on this
subject. He recommended Citric Acid initially - I would assume because the
effect was good and citric isn't terribly dangerous stuff. However, he
mentioned to me that he is now using dilute Hydrochloric or Nitric. The
Nitric's added benefit is that the 'reversed' tones (commonly thought of as
solarized) come back to their proper levels in the Nitric bath because it is
oxidizing. If you don't use the Nitric, the tones come back to life usually
within 24 hours, and within 30 seconds in a very dilute hydrogen peroxide
bath. The nitric's downfall, as we all know (or should know) is that Nitric
is nasty stuff in concentrated form.

Mike mentioned to me that he is concerned that the citric poses problems if
it isn't completely washed out. He thinks the print may be more susceptible
to "(reversible) fading in light".

So.. why didn't I go straight to the source and just say this? A couple of
reasons here. First, because I wanted to refer Maylee to Ware's instructions
which mention only the citric bath, I didn't want to point to a good source
of info and simultaneously make modifications. I also assumed that the kit
contained citric for this purpose. And lastly, and maybe wrongly, I didn't
want to start another discussion about safety and hazardous chemicals.
Neither ntric nor hydrochloric are forgiving acids, and I don't like
recommending their use. However, and for this I thank you Judy, it would
have been best to post ALL the facts and save these keystrokes..

Best,
Adam

Judy Seigel wrote:

> 7
>
> On Mon, 28 Jun 1999, Adam Kimball wrote:
> >
> > Firstly, get or make a new sensitizer. With 10x too much dichromate,
> > you'll have a very short scale and a grainy result. Secondly, get some
> > Arches Platine to practice with. Thirdly, clear in 4% Citric Acid. And
> > lastly, buy Ware's book when it comes out...
> >
>
> Adam, would you explain why you use the citric acid clearing bath? I had
> the impression that Mike Ware no longer advocated citric (for archival
> reasons) & had switched to nitric or HCL... I think his book will have
> more about that, but.... in the meantime.... ???
>
> Judy



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