Chromoskedasic is a unique darkroom process that provides fun darkroom experimentation for those who like to put "play" back into the darkroom. In a nutshell, a black and white print that has been freshly developed but not yet fixed is subjected to two mild photographic solutions, an activator and a stabilizer, while under room light. These chemicals in the presence of light will produce deep red-browns, blues, yellows, oranges, greens and even purple. Saying the word "chromoskedasic" is more complex than doing the process, ultimately. It is a perfect one to teach to students to loosen them up in the darkroom. However, as with any experimental darkroom process, matching the correct image to meld well with the process is key.

The history of the process starts with Dominic Man-Kit Lam who first wrote about it in Scientific American (November 1991). Another key player in chromoskedasic printing is William Jolly who did major research into the whys and hows of "chromo" (for short) at Berkeley. A Google search will turn up his articles. A third key player, Alan Bean, has made this his signature process for years. His article appeared in View Camera magazine (September/October 1992).This quick and easy method owes much to these three men who spent large amounts of time to come up with good conclusions on how the process works. An extensive description of all chromoskedasic processes can be found in my Experimental Photography Workbook, but for now, this article will be all that you need to get started.

A BW print is normally monochromatic because the silver particles that remain in the print absorb all color and reflect black. In chromoskedasic printing, the silver particles are carefully managed with different chemicals and/or exposure to light, to become different sizes. These different sized silver particles in turn scatter light in different ways to produce the different colors; this is known as the Mie effect. The chemicals used to do this are an acetate buffered thiocyanate "stabilizer" and a dilute potassium hydroxide "activator". The colors only appear where there is white in the print, thus a high contrast print or one that has appreciable areas of white will be best for this process.

SUPPLIES NEEDED

Black and white gelatin silver paper: An excellent choice would be Ilford Warmtone. Fotospeed Lith is another excellent choice.

Activator and Stabilizer chemistry: Mix up these two solutions:

• 20% solution of stabilizer - 1 ounce in 4 ounces water
• 20% solution of activator - 1 ounce in 4 ounces water

This amount is enough for a one-person session of printing. For a class, each student should have their own solutions next to his/her work area. The stabilizer will stay clear, but the activator will turn dark brown and full of particles of silver. Do NOT throw this away if you want lots of silvering out to occur. In fact, an old solution will produce much better silvering out for you as it ages.

Brushes: my first recommendation would be a fat calligraphy brush, the kind that holds a lot of fluid in its belly and yet comes to a fine point. It will silver out with use, so dedicate it to the process. A variety of brush sizes would be nice, one that can easily cover a print with solution like a cheap foam brush, and then a tiny detail brush as well. Cheap is fine.

Normal black and white darkroom chemistry: developer, fix, hypoclear