I've been playing around with alternative film chemistry, and I realized there isn't really a yellow counterpart to the cyanotype, a xanthotype so to
speak. There are some processes which result in a pinkish or red color, but none for yellow. Anyway, just out of my own curiosity, I have been trying
to figure out a way to develop a so-called xanthotype. Of course, I could cheat and use a generic process which works with any pigment, but where's
the fun in that?
The blue color of cyanotypes come from prussian blue. My attempts thus far have been to use yellow iron oxide, Iron (III) Oxide-Hydroxide monohydrate.
Of course there needs to be some sort of light sensitive chemical to expose. Nitric acid seems to be a good candidate. Nitric acid reacts with iron to
form the nearly colorless Iron (III) Nitride. When nitric acid is exposed to light, it decomposes to water, nitrogen dioxide, and oxygen. The question
is, how do I get the iron to oxidize specifically to the yellow form?
Is this idea even feasible? Do you guys have any other ideas on yellow, alternative, photographic processes? I'm trying to avoid anything which uses
things like platinum, palladium, gold, or silver.woelen - 7-3-2013 at 08:12
I missed your post of half a year ago and I hope it still is relevant for you.
I have developed a process for yellow toning, based on vanadium ferrocyanide. I have written an article about this subject. Only easy to obtain
chemicals are needed.
The following is a page on my website about ferrocyanide based toning and it contains a link to the article I have written on this subject.
[Edited on 7-3-13 by woelen]CHRIS25 - 7-3-2013 at 13:46
I am sure you are aware of some of the bleaching processes that force the blue in cyanotype to fade away; but I have a formula for yellow that to date
I have not tried. You could experiment with either direct immersion without the bleaching process or bleach a little and then submerge in a solution
of trisodium phophate at one tablespoon to one pint of water, make sure the water is warm and submerge the cyanotype in this for anywhere between 20
minutes to 40 mins.
I have though experimented with many colours with cyanotype so if you want tips please feel free to ask.woelen - 7-3-2013 at 23:28
I knew that method. It is based on the fact that the blue ferro ferricyanide is not stable at high pH and decomposes to Fe(OH)3 and ferrocyanide. The
Fe(OH)3 causes a yellow/brown stain. From personal experience I found the color to be too faint. The vanadium-based toner gives very nice bright
yellows which can be combined with blue in the same process to obtain bright greens (like grass) or cyan color.CHRIS25 - 8-3-2013 at 00:13
Slightly disorientated here Woelen, I understand that ferri- oxidizes to ferro during the exposure to UV, and then the insoluble ferro is washed away
in the water. But you used the words: ... blue ferro ferricyanide is not stable at high pH ... I presume by this that you mean there are ferro and
ferri ions existing together after the UV, which I did not think was the case. And secondly : ... it is unstable at high PH ...do you happen to know
how high? since we use acids in various strengths and solutions to aid and assist in permanence and increasing tonals and I often wondered how
concentrated I could make a solution.
PS do you have a recipe for Mauve type violet, I made it one day by accident and after numerous tests could never repeat it ever, that was soooo
dissappointing. Just had to ask.woelen - 8-3-2013 at 04:20
The deep blue color in blue toner and also in the cyanotype process is due to a compound, sometimes written as KFeFe(CN)6. This compound contains
iron(II) and iron(III) in the same complex ion [FeFe(CN)6](-) and it is this combination which gives the deep blue color. This complex decomposes at
moderately high pH (e.g. 11) to form Fe(OH)3 and [Fe(CN6)](4-). The latter is a very pale yellow ion and goes in solution. The Fe(OH)3 is a brown
solid.CHRIS25 - 8-3-2013 at 05:08
Thankyou Woelen, I should have read my literature in more detail. I misinterpreted High PH to mean 1 or 2. otherwise High acidic. Stupid.sonogashira - 23-10-2013 at 01:40
"On account of the impossibility of obtaining the less common organic chemicals in the United States during the past few years, university
laboratories have had no option but to prepare their own supplies."
While this was written about universities in early WWII, it appears equally pertinent today for the amateur experimenter. Things are getting harder to
obtain and this fairly short book contains many interesting procedures.
