[alt-photo] Re: Speedy Cyanotype Question LONG POST

[Christina Anderson]

Francis,

I learned lots from Sam Wang about cyano. He was so good with that process.  I've got his cyano chart somewhere, of the different formulations graphed out.

By increasing the FAC to 2:1 with the 20% FAC and 8% PF I find it about a stop difference in time and I think Sam might agree, but he's in China basking in his huge show right now.

We had a great discussion a while back with Alberto Novo chiming in.  I am cutting and pasting notes I have saved on this topic--since this was on the list and is still the list.  It was just too good of a convo to pass up.  It is NOT organized so you will have to realize what was said in what order, but it may answer some interesting questions for you.  But if grain is not your issue, then maybe all the below is not necessary to the shoe project.  But I'd file it anyway...because it's good stuff, why this list is so useful.
Chris
PS Hope you're coating the shoes carefully--I apparently had spilled some cyano wash water down the side of my cabinet in my bathroom and didn't notice it until over the course of the last several months I've now got a Jackson Pollock blue vanity :)
 

From the alt list:
I don't believe anymore that there is a traditional or classical cyanotype. Here are the compositions in g/100 ml in sol A:B and their ratios, gathered  from different
sources: 12.5:4.5 = 2.78 Wall (Photographic Facts and Formulas, 1924) 24:7 = 3.42 Namias (Chimica Fotografica, 1929) 36:16 = 2.25 Clerc (La Technique Photographique, 1950) 25:12 = 2.08 Glafkides (Photographic Chemistry, 1958) 22:15.4 = 1.42 Nettles (Breaking the rules, 1977) 25:25 = 1.00 Frederick (Creative Sunprinting, 1980) 20:8 = 2.5 Barnier (Coming into Focus, 2000) Note that the ratio 25:12 (Glafkides) is very close to the optimal ratio Fe  am. citrate/ferricyanide which gives themaximun yield in Prussian Blue.  Higher values (an excess of fe am citrate over ferricyanide, requested for  the formation of Prussian blue) give more sensitivity but also bleeding.  Lower values (an excess of ferricyanide) give no bleeding, lower sensitivity  and more contrast. DMax is proportional to the amount of Prussian Blue, so I
suggest to choose  a formula with a ratio equal or lower than 2.08, possibly increasing the  overall concentration. Cyanotype is also very sensitive to alkalinity in the  paper
(most of them are buffered with calcium carbonate) and in the water,  so a first soaking (not more than 30") in acidic water is higly recommended. Alberto
Not against the mottling (it might depend on the internal sizing of Plaine), but against bleeding and staining: try increasing the amount of k ferri, for example using a 1A:1.25B ratio or more (or less than 0.8A to 1B). You will also have a little more contrast and longer exposure times.   Alberto
My interest in the bleeding was wondering if the FAC was the culprit, if its molecules are the bigger ones that maybe don't sink in as well into the paper fibers, because it is the increased FAC that bled.
There is an interesting patent on blueprints, cited also by M. Ware but not deeply enough IMHO (Crawley et al., US 2,350,991), where the author speculates about bleeding / non bleeding formulations regarding their ratio of (light-sensitive ferric compound)/(iron cyanide compound). For ratios above 2 (that is, an excess of light-sensitive iron) bleeding occurs due to a lack of reacting iron cyanide (this patent deals with mixtures of ammonium iron oxalate and potassium ferri- and ferro- cyanide).
Ammonium iron citrate (green) is given with an iron content ranging from 14.5 to 16% as Fe.
My calculations are that, for a 10% potassium ferricyanide, the non-bleeding equivalence would be a solution of ammonium iron citrate (green) between 20 and 23%. If so, 25% is in the bleeding range.

My experience is that, despite the enhanced exposure times due to the filtering effect of ferricyanide, a lower concentration of am fe citrate (or an higher concentration of k ferricyanide up to 1:1 to am fe citrate) gives no bleeding, deeper blue and contrasty images than the usual 10:25 (K ferri : am fe citrate) formula.

As for the effect of the acid washing, I have noted an increasing staining of highlights leaving the prints in acidified water for more than 10-20".

Ware himself recommends a "half a minute in very diluted hydrochloric or nitric acid" (10 cm3 to 1 litre  water)" ("Cyanotype", pag. 107) and that "a lesser dilution of a more diluted stock solution of acid may be preferred". Also, "These [acid] developments baths tend to accumulate Prussian blue, which will eventually begin to stain the paper" (p. 108).

BTW: I have noticed a very different behaviour between 300 and 600 g/m2 Fabriano Artistico, the latter giving deep blues and contrasty prints than the former. I don't know if this is due to a different absorption or a different sizing.   Alberto

AHA Alberto,

This is exactly what I am looking for.  My formula is 20%A to 8% B thus a 2:1 is 40%A: 8%B, so by your calculations, anything above using a .92A:1B would promote bleeding--even 1A to 1B would do so, which is what I find in practice.

My guess was always that there was too much of SOMETHING in the formulation that created the runoff, but I never knew what the "something" was until I saw how smooth and non-bleeding the side by sides were with increased potassium ferricyanide.  But I wasn't sure I could trust my eyes nor did I know the chemistry reasoning behind the observation.

In Ware's book he defines an average of the two as being a 26% A to a 12% B which would also follow your guess, below--being the most of A that might work with B without bleeding.  It would equiv to your formula of 21.6%A to 10%B, comparing apples to apples.  Thanks for this tidbit, it really clarifies things for me. Maybe an unrelated question--is it **possible** that the bleeding in pt/pd could similarly be caused by an excess of iron? Chris

My calculations are that, for a 10% potassium ferricianide, the non-bleeding equivalence would be a solution of ammoniium iron citrate (green) between 20 and 23%. If so, 25% is in the bleeding range.

My experience is that, despite the enhanced exposure times due to the filtering effect of ferricyanide, a lower concentration of am fe citrate (or an higher concentrtion of k ferricyanide up to 1:1 to am fe citrate) gives no bleeding, deeper blue and contrasty images than the usual 10:25 (K ferri : am fe citrate) formula.

The explanation why an excess of "reactive iron" to "color-forming iron" (i.e. K ferri) produces bleeding would be that the reacted iron moves from its original position faster than the K ferri reacts with it.  So I second that this would apply also to other iron processes, substituting the "color-forming iron" whith whatever reacts with the photochemically formed iron(II). The calculation have to be made with moles and not grams. Note that am fe citrate is the only poorly defined substance (a 14.5-16% Fe). Alberto

I don't believe anymore that there is a traditional or classical cyanotype. Here are the compositions in g/100 ml in sol A:B and their ratios, gathered from different sources:

12.5:4.5 = 2.78 Wall (Photographic Facts and Formulas, 1924)

24:7 = 3.42 Namias (Chimica Fotografica, 1929)

36:16 = 2.25 Clerc (La Technique Photographique, 1950)

25:12 = 2.08 Glafkides (Photographic Chemistry, 1958)

22:15.4 = 1.42 Nettles (Breaking the rules, 1977)

25:25 = 1.00 Frederick (Creative Sunprinting, 1980)

20:8 = 2.5 Barnier (Coming into Focus, 2000)

Note that the ratio 25:12 (Glafkides) is very close to the optimal ratio Fe am. citrate/ferricyanide which gives the maximun yield in Prussian Blue. Higher values (an excess of fe am citrate over ferricyanide, requested for the formation of Prussian blue) give more sensitivity but also bleeding. Lower values (an excess of ferricyanide) give no bleeding, lower sensitivity and more contrast. DMax is proportional to the amount of Prussian Blue, so I suggest to choose a formula with a ratio equal or lower than 2.08, possibly increasing the overall concentration. Cyanotype is also very sensitive to alkalinity in the paper (most of them are buffered with calcium carbonate) and in the water, so a first soaking (not more than 30") in acidic water is higly recommended. Alberto

Christina Z. Anderson
christinaZanderson.com

On Apr 9, 2010, at 2:16 AM, John Brewer wrote:

> Hi Francis,
> 
> The dichromate is a highlight restrainer and the oxalic acid I believe is
> insurance against slightly basic paper. 
> 
> John.
> 
> 
> 
> 
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