From: K (kerickso@acs.ryerson.ca)
Date: 11/07/01-11:04:24 AM Z
I just did this last night, and from what I saw, the blotching may occur in
the carbonate bath, where the print (especially smaller prints) tend to
float to the top. I don't know if floating is really the problem, but either
way, I could see the heavier blue densities in the border take much longer
to get to the same red-brown colour as the image area. When i agitated the
image in the tray, all of the blotching for me disappeared.
Incidentally, I'm wondering if the presence of dichromate in the cyanotype
mixture affects the toning. I use a straight a+b solution for all my
cyanotypes (ferricyanide and ferric ammonium citrate only). I had difficulty
getting brown tones (most were purple to deep red), and when I did, it was
with a lot of paper stain (at first); brown-black tones seem untenable
(though i still have a lot of experimenting to do). Most of the action, I
found, took place in the carbonate solution, and my best results were from a
long 1st bath in tannic acid, a carbonate bath of the minimal length to
convert the cyano from its blue colour (about 2 to 3 minutes otherwise the
prints go purple), and a final VERY short (10 to 20 second) dip in the
tannic acid bath, with 30 to 60 seconds wash in clean water between each
step, and a minute or so final wash. I'll be trying it again, so maybe i'll
provide something more conclusive in addition to these results next time.
Quick question: does anyone know if nitric acid can be had outside a
chemical supply store? Maybe a pharmacy? A greenhouse?
Thanks,
Kris
----- Original Message -----
From: "Judy Seigel" <jseigel@panix.com>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Tuesday, November 06, 2001 7:16 PM
Subject: toning cyanotypes
>
> Here's a note to help fill in the dread silence: A while back Shannon
> asked some questions about toning cyanotype, where it seems she was
> getting uneven results, even blotches. She hasn't said since then if she
> solved the problems, but here are some suggestions.
>
> If you want to MATCH tones, the beginning prints have to be the same (that
> is printed to the same depth on the same paper), and the toning has to be
> the same, that is you have to use the baths one-shot, and time all rinses
> and dippings to be identical...
>
> That's not to say you couldn't hit on the same effects accidentally, but
> odds are against it -- especially since what's carried over from one bath
> changes the next. Also, timing is a critical variable, and, as the baths
> change, timing changes.
>
> As for the blotching, I've never seen that, and it may be that particular
> tannic acid supply was especially gummy. But it couldn't hurt to make up
> the stuff an hour or so in advance. We made a huge beaker full, of both
> the tannic & the sodium carbonate, then poured enough into the tray at a
> time to just cover.
>
> You also want to change the rinse water often... and do NOT use your
> presoak water to rinse between baths... that's another variable (a big
> one). Presoak has to be clean.
>
> In my experience, prints that are very deep (lots of rich blue on an
> absorbent paper) usually tone best. "Regular" prints on smooth paper
> tend to lose too much density. I've seen cases where the resulting pale
> toned print was exquisite, but more often just blah.
>
> Judy
>
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