Blogging for Freya: The Difference in Splitting

Two-Stage Cyanotype, First Test.

I missed my deadline, Spiders, but I almost had a good reason. I was engaging in a new experiment today and it wasn't finished until I got home from game night. Of course, I could have done the experiment earlier in the day... but I hardly ever get work done before 2 PM. Oh well! Next week, Thor! For sure!

Apparently it is possible to print cyanotypes in a very different way than the traditional method. In traditional cyanotypes, there are two active chemicals. Ferric Ammonium Citrate (A) and Potassium Ferricyanide (B). Generally, Parts A and B are added together in equal measure to create a working solution. The working solution is then painted onto the substrate, allowed to dry fully, exposed and developed in water.

According to Mike Ware and a photographer named Jorj Bauer, it is possible to split A and B apart. The process then becomes an application of Ferric Ammonium Citrate to your substrate, dry for 30 minutes (far less time than required normally), expose, then develop by brushing on the Potassium Ferricyanide. Afterwards only a short water bath, instead of an extended wash, is required to clean off excess chemistry. All the development occurs with the Potassium Ferricyanide being added.

The advantage here is that you don't need to mix up working solution, which goes bad fairly quickly. You can keep your coated paper longer, and coat large projects more easily and without waste. Also, because the Potassium Ferricyanide partially inhibits UV light, waiting to add it until after the exposure dramatically increases the sensitivity of the print. A 200-300% increase in sensitivity is possible, at least theoretically. This drastically reduces the time required for exposures, and the depth of the shadows. Again...in theory.

I tried to use this technique today with a photogram on parchment and had... well, it's right up there, Spiders. It isn't a great success. Now, yeah... I took a shortcut and used a hairdryer to accelerate the drying of the Ferric Ammonium Citrate-coated parchment. However, I think the problem lays with how damn thirsty the parchment is. Because it absorbs and holds onto liquids with such tenacity, the Ferric Ammonium Citrate (absorbed fully into the parchment) does not easily interact with the Potassium Ferricyanide (only on the surface). Possibly a bath in the Potassium Ferricyanide might work as a developer... maybe. But that causes problems because even with only two or three minutes of contact, the Potassium Ferricyanide has left yellow stains on the image that did not wash out at all in the water. I'm afraid of trying an acid wash (generally recommended to clear highlights of cyanotypes) because that's un-mixed Potassium Ferricyanide. When combined with acids, Potassium Ferricyanide can produce cyanide gas. Not something I want to mess with.

So, maybe this works really well on paper? I'm certainly going to do some more testing... but I'm thinking it isn't going to be a great technique for me and my parchment prints. Bone, maybe? I hope so. It might solve some of my issues with the bone images self-developing while they try to dry. I'll have to do a test once I get some bone "scraps" I can fiddle with.

For the weekend and next week, dear Spiders, I have other things to play with. Aside from making further progress on my grant project, I've also got to work on a good way to clear the highlights of my parchment prints. I have some citric acid crystals that I'm going to whip up into an acid bath and see if I can get the highlights to clear. Acid helps iron salts dissolve, and that may get the yellow out of the parchment. Since those prints are done traditionally, the cyanide is not going to be released and the clearing bath should be safe. Supposed oxalic acid works really well, but I've been looking around and gotten some good feedback about citric acid. Oxalic acid is fairly unpleasant stuff by my standards, so I'd prefer to avoid it.