Interesting cyanotype toning result...

[KYsailor]

Was experimenting with toning some cyanotypes - while the blue can be nice on some images, I prefer a more neutral black or even black/blue. Was reading the Annette Golaz book on botanical toning and ran across the use of sweet potato skin for getting a black/anthracite tone. Well, I just happened to have some sweet potatoes around ( I roasted and ate them after I used the peels per her directions) and made up the toning solution. In the past I have tried some black tea and coffee, more dark sepia than black and lots of staining.

I also had some test cyanotypes I had made to compare some printing settings for the negatives and proceeded to give it a try. I was initially disappointed - if I did straight toning, with no other pre-treatment, nothing much seemed to happen, I took one that was sitting in the toner and put it in a weak sodium carbonate solution I was using to recover some of my overexposed cyanotypes. Bleached it for a bit - maybe a minute and put it back in the sweet potato extract seemed to change the color to a more violet, again not impressed - so I put it back in the bleach for another minute or so.. them back in the sweet potato solution... and went on to some other things. Came back in a few minutes and looked at the two prints - the unbleached one looked about the same as when it went in - maybe a slight color shift and the bleached one was a bit kind of violet/blue.... I assume a failed experiment - put them out to dry.

Looked at them the next day I was surprised that the bleached/toned print had dried down to almost a dark back, with a slight blue tinge in the shadows. I had printed Canson Bristol XL and the surface was pretty delicate after all the time in the tray and I had some marks where the paper had been abraded by my sloppy handling. The paper was also somewhat stained but not terribly. Nevertheless, I was actually pretty pleased with the tone of the final prints. Has anyone else ever tried this? The sweet potato approach is kind of a pain ( and you have to eat a lot of sweet potatoes) from what I understand it is the tannin that creates the black tone - I think I will just get some tannic acid and see if I can get similar results. Have others obtained similar results with a toned cyanotype?

Thanks

Dave Najewicz

David Najewicz Photography

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[Nicholas Lindan]

...The sweet potato approach is kind of a pain ( and you have to eat a lot of sweet potatoes) from what I understand it is the tannin that creates the black tone - I think I will just get some tannic acid and see if I can get similar results. Have others obtained similar results with a toned cyanotype?

I have used tannic acid, it gives a slightly warm black result. The results were quick and didn't increase over time - very WYSIWYG. I was interested in permanency so I stapled the print to the deck railing and let it sit outside - after a summer's worth of sun and rain it hadn't changed tone.

That said, I really like the look of your sweet potato example. How much of a PITA is it?

 

[KYsailor]

I have used tannic acid, it gives a slightly warm black result. The results were quick and didn't increase over time - very WYSIWYG. I was interested in permanency so I stapled the print to the deck railing and let it sit outside - after a summer's worth of sun and rain it hadn't changed tone.

That said, I really like the look of your sweet potato example. How much of a PITA is it?

well it required the skins of two large sweet potatoes - about 60 grams ... I cut them up into about 1/4" size dried them in a low oven so it was clearly less than 60 gm afterwards. Boiled 1 liter of water - ours here is about pH 8.7 and (7 grains hardness ... Kentucky is all limestone) added to peels and let set for 15 minutes. Added prints while water was about 125F... but it cooled as I messed around with the various prints. Toner solution was slightly brown tinted. I did seem to loose some highlight detail due to the bleaching - here is a copy of the orignal showing more tonality in the flower petals....

 

[nmp]

Some folks like to alternate bleaching and toning baths, thereby progressively getting more and more neutral tone. With no bleaching, like what you got, there is very slow self-limiting toning mostly resulting in a slightly darker color. Bleaching creates ferric hydroxide which is faster for tannin molecules to attach to and the resulting color is more dark brown, almost like a un-toned salt print. With partial bleaching, brown and blue complement each other to make a more neutral tone. At least that's my take on it.

:Niranjan.

 

[KYsailor]

Some folks like to alternate bleaching and toning baths, thereby progressively getting more and more neutral tone. With no bleaching, like what you got, there is very slow self-limiting toning mostly resulting in a slightly darker color. Bleaching creates ferric hydroxide which is faster for tannin molecules to attach to and the resulting color is more dark brown, almost like a un-toned salt print. With partial bleaching, brown and blue complement each other to make a more neutral tone. At least that's my take on it.

:Niranjan.

Mr Patel,
Thanks for the observations and some insight into the chemistry ( as a retired mechanical engineer, chemistry was never my strong suite). Nevertheless, it makes sense and I was pleasantly surprised by the neutrality of dark tones upon dry down. I will have to try this again to see if I can achieve similar results. The only downside is the loss of some hightlights and some slight staining. As someone new to the alt process world, I greatly appreciate the comments by you and some of the others who are well versed in this area.

Dave

 

[nmp]

Mr Patel,
Thanks for the observations and some insight into the chemistry ( as a retired mechanical engineer, chemistry was never my strong suite). Nevertheless, it makes sense and I was pleasantly surprised by the neutrality of dark tones upon dry down. I will have to try this again to see if I can achieve similar results. The only downside is the loss of some hightlights and some slight staining. As someone new to the alt process world, I greatly appreciate the comments by you and some of the others who are well versed in this area.

Dave

You are welcome. I do my part. I am also learning as I go along. Having an undergarguate degree in Chem E, I don't fear chemistry (or may be it was the other way around.) Obviously I am not a chemist chemist so I can't predict or make up some new chemistry but I will understand it if it is explained to me, perhaps a little better than someone like yourself with mechanical engineering background. But then I couldn't make a piece of hardware if my life depended on it. Or put together some electrical gizmo on my own.

:Niranjan.

P.S. Nice cyanotype, by the way.