new cyanotype process development

[earlj]

After Mike Ware provided a link to his updated Cyanomicon (https://dl.dropboxusercontent.com/u/...Cyanomicon.pdf) I set to work to reacquaint myself with the new cyanotype process. I mixed up a new batch of sensitizer. I decided to try Fabriano Artistico Extra White hot pressed for the paper, but it turns out to have an alkaline buffer. I acidified it with 10% sulfamic acid and tried again. I decided to use one of my favorite 8x10 pinhole negatives. I found the exposure that resulted in the first two steps of the step tablet reading the same. For the first batch of prints I used 10% sulfamic acid for the first bath. The highlights were dark, indicating that the process has a longer tonal scale than my negative. I tried again with varying amounts of potassium dichromate in the sensitizer for contrast control. This print used 12 drops of 1% potassium dichromate.

Then, dismayed by the amount of sulfamic acid required for the first bath for the first few prints, I took Mike Ware's advice and looked for a mineral acid. It turns out that the local hardware store sells muriatic acid (31.45% hydrochloric acid) for $8.99 per gallon, and it can be diluted to 1% for the first bath. Cost effective. So here it is.

September 2012, Cumberland, Wisconsin
8x10 - f250 (100 mm, .400 mm aperture)
Efke PL-100 film
Fabriano Artistico Extra White hot press
acidified in 10% sulfamic acid
12 drops of 1% potassium dichromate added to 3 ml of new cyanotype sensitizer
1% HCl first bath
washed in distilled water (no tap water used)

Cyanotype001.jpg

[JoeVanCleave]

That's wonderful, Earl. I'm looking forward to watching your progress with this new process. Please keep posting more.

I've seen example images of cyanotypes toned in tea (I think) where the image looses its blue hue and takes on a much warmer tone. That kind of a process would interest me.

Keep up the good work.

~Joe

[earlj]

This is the finest cyanotype that I have made. It encourages me to embrace the blue - to add this process to my choices of expressive media with which to render my images as physical objects.

I have never been impressed with toned cyanotypes - the toning agent stains the paper and the tonal range of the original is reduced by toning. If I want a black or brown print, my time and efforts are much better served by working in van dyke, salted paper, argyrotype, or pt-pd. Despite its seeming simplicity (with plain water development) the process of creating a fine cyanotype requires a similar level of technique and attention to detail to any other 'alternative' photographic printing process.

That's my story, and I'm sticking to it . . . . .

[banana_legs]

Earl,

This is rather super. I too think cyanotype is under exploited. I have a bottle of Mike Ware's formula, but I have yet to have good success as all my papers are heavily buffered. I may break out the acid and try again after your inspiring image.

Best regards,

Evan

[earlj]

Evan - I chose sulfamic acid for acidifying the sheets based on some posts to the alt-process list that indicated good success with a range of processes. I have sulfamic acid on hand for mixing up Mike Ware's argyrotype sensitizer (my favorite iron/silver process). I found 5 lb on ebay for $29.99, which is cheaper than the grout cleaner at the home improvement store. At 10% (w/v) the bubbles stop after 30 minutes. I think that I will treat just about every paper I use for new cyanotype, argyrotype, and salted paper, as these processes are all very sensitive to paper chemistry.

[Ned.Lewis]

Earl, is there a reason sulfamic acid is preferable to acetic or citric acids? The cyanotype looks like it goes all the way from dense dark to nice highlights, well done!

[earlj]

Thanks, Ned. I am not sure about the chemistry of removing the alkaline buffering agents. I used sulfamic acid because that is what I have on hand. People on the alt process list report good success with many different acids for this purpose.

The first bath for the exposed print is a different story. I ran out of sulfamic acid, and tried citric acid for this bath, and the results were not good. The print was weaker - the dmax was much better with both the sulfamic acid and the hydrochloric acid. I know that sulfamic acid is an iron chelating agent, and that it is used in coffee pot cleaners for that reason. I think that it is better at washing out the unexposed iron salts. Mike Ware recommends nitric acid at 0.25% - 1% v/v for the first bath.

A quote from Cyanomicon by Mike Ware, page 164: "If there are safety objections to using nitric acid, then 0.25% - 1% v/v hydrochloric acid may be used. If there are safety objections to this, then 5% - 10% w/v sufamic acid could be used, or as a last resort, 1% - 5% w/v citric acid. Acetic acid is not recommended because it tends to form insoluble coloured basic ferric acetate."

I got great results using both sulfamic acid and hydrochloric acid. I will continue to use the latter, as it is considerably less costly. I will continue to look for a source for nitric acid, as it may be even less costly than HCl.

[Ned.Lewis]

Thanks, yes, I was thinking of acidifying the paper initially. I did not get a successful calotype until I acidified my paper. I used diluted vinegar, but I read of others using citric or sulfamic acid. When I saw you used sulfamic it caught my attention. It all seems a bit mysterious.

It makes sense that the acid in your first bath after exposure matters a lot. It's interesting how many choices can work!
There is an iron-based variant of the calotype method I'm using, and that will someday be my first foray into all this...

[earlj]

Here's a very interesting discussion from APUG: http://www.apug.org/forums/archive/i.../t-118153.html. It looks like sulfamic acid may be the best choice for acidification of alkaline buffers in art paper.

[Ned.Lewis]

Earl, thank you that was very interesting to read. I will get sulfamic acid when I make my next order. These processes take enough effort and have so many stumbling points, it is worth attending to details to improve the chance of success!