Cyanotype process 1 - Sensitizer and Papers

My cyanotypes have for the most part been created using the new cyanotype process pioneered by Mike Ware (see Resources page for details). The kit for this sensitizing solution is available at Photographer's Formulary and also Rainier Photography (Seattle) and other places. This improved chemistry incorporates the use of ammonium dichromate which is somewhat more dangerous but provides for shorter exposure times, heightened intensities, and a greater tonal range. It is possible to make this formula from bulk chemicals but (at least so far) it does not seem preferable to do so, given the quantities, availability, and price.

I use primarily 22" x 30" Arches Platine paper which is specifically designed for alt-photo printing. It is a fine-arts paper made from 100% cotton fiber, with a neutral pH and no added alkaline buffers, which can cause problems for cyanotypes, which prefer a neutral to slightly acid environment. I have also used Rives fine-art printing papers, which give a somewhat softer, warmer image, and also Arches hot-pressed watercolor papers.

The papers are brush-coated with the Ware cyanotype solution in a very dim tungsten light. I add one drop of 40% citric acid solution per 2 ml of sensitizer to facilitate clearing of the image during development.

Cyanotype process 2 - Negatives, Exposure, and Development