What is the Argyrotype printing process? A lot of you have probably never heard of it. Some of you have, of course, and maybe have even made prints. It’s one of the more obscure iron-silver print processes, also known as siderotypes. To me, it’s a viable and wonderful POP process for my wet and dry collodion negatives.
Mike Ware is the inventor of this process. his PDF on workshop notes says, “The Argyrotype process is a latter-day improvement on the late nineteenth century processes of Kallitype, Van Dyke, Sepiaprint, and Brownprint, which were all, in turn, offspring of Sir John Herschel's Argentotype of 1842, the first iron-based silver printing process. The difficulty with these processes lies in clearing the print of iron salts, without dissolving the image silver in the presence of the oxidizing nitrate ion, for which alkaline developers were necessarily recommended, but are not very effective in removing the excess iron(III) salts, which is better done in acid. The Argyrotype version was devised in 1991, employing an unusual silver salt - silver sulphamate (called Sulfamic Acid in the U.S,)- to avoid the problems of image loss caused by silver nitrate, and to enable mildly acidic (pH 3.5) working conditions. It provides a 'single-bottle' sensitizer solution, having a long shelf-life, a contrast controllable by added acid, and an image colour that can be ‘fine-tuned’ by the humidity, and the incorporation of a humectant – glycerol. The resulting purplish-brown print of nanoparticle silver has a finer gradation than the traditional iron-silver processes, and good prospects of endurance for a plain paper silver image (which can be notoriously vulnerable) because it is believed to acquire partial sulphide-toning in the processing, which stabilizes the silver.”
When you make the chemistry for this process, you quickly realize what he’s talking about here. Sulfamic Acid, Silver Oxide (Ag2O), and Ammonium Iron (III) Citrate are ingenious ways of handling this problem. But they are, as he says, more vulnerable to chemical attack. “Brown silver images consist of metal particles much smaller than those constituting the black silver images of modern gelatine-silver halide papers; the former have colloidal dimensions (ca. 20nm) - far smaller than the wavelengths of visible light (ca. 500nm) - and their colour is due to a specific absorption of light which is dependent on their shape, size, state of aggregation and chemical environment. Such small particles are inevitably more vulnerable to chemical attack: they present a relatively large surface area and are rapidly dissolved by reagents that 'etch' or 'bleach' (i.e. oxidise) silver. The inherent problem of the iron-based silver processes lies in the danger of leaving residual ferric iron in the print - to its ultimate undoing, because iron(III) will oxidise silver with consequent degradation of the image. It is this problem that the Argyrotype process has been designed to avert.”
I’m very interested in the Siderotype printing processes. Other than Oil Prints (which does not use silver nitrate), these are strong candidates for printing my new work. I’ve found the Argyrotype process very simple and extremely beautiful. I highly recommend a Platinum or Palladium toner. It’s simple to make, makes the print “sing” and will ensure the longevity (life) of the print.
Platinum or Palladium Toner:
1L DH2O
10g Citric Acid
10 drops of Platinum or Palladium or both (5 drops each or any combination) at 20%.
Use once and discard. For example, I used 150ml for this print for 3 minutes and discarded the toner.