Cyanotype - color it blue - 19th century photographic process offers creative photographic printing alternatives

PSA Journal, June, 1991 by Louie Powell

In 1839 two events occured which began the era of photography. Daguerre read a paper at the French Academy of Sciences in which he announced a process for producing a permanent positive image on a metal plate--a process which came to be known as the Daguerrotype. The Frenchman claimed he had been using this process for six years.

The same year, an Englishman, Henry Fox Talbot, announced to the Royal Society that he too had developed a process for photography. In this instance, however, the process led to a negative image on a paper substrate. Fox Talbot reported he had four years of experience with his method.

Students of marketing know that just about any publicity is good publicity if it serves to increase public demand for a product. Such was the case in the early days of photography. Daguerre and Fox Talbot's competing claims to be the inventor of photography led to an enormous increase in public interest--even though both methods were slow, messy, impractical and for the Daguerre process, dangerous. As a result, there followed a great deal of research into other ways to make photographs.

In 1843, Sir John Herschell read a paper to the Royal Society in which he discussed two topics:

* First, light will bleach the juices extracted from certain flowers, a process he called Chrysotype or Anthotype.

* Second, when ferric salts are exposed to sunlight, they are reduced to the insoluble ferrous state, a process known as Cyanotype.

Of these two, the Cyanotype process proved to be a very practical method to produce permanent images, while Chrysotype was shown to be completely useless. Cyanotype was a common experimental photographic process through the 1850's, and for a period there were even commercial iron papers. By the mid 1870's, however, the silver process we know today had matured to the point where Cyanotype was no longer used for photographic objectives, but it remained a viable process for reproducing technical drawings until the diazo process became available in the 1950's. Many PSA members who are involved in engineering or architecture will recall wetprocess blueprints which were white images on blue backgrounds.

Cyanotype still lives today. Usually thought of as an experimental, non-silver alternative process, it is also an option to be considered for its creative value when its characteristic blue iron stain color will add to the final image.

How To Get Started:

Cyanotype is a process which can be easily employed today for creative purposes. Darkroom requirements are minimal, but one needs two essential ingredients.

Negatives:

Cyanotype is a slow contact printing process, and as such, requires negatives the size of the final print. For most applications, this means that the original negative must be shot using a large format camera, or else an enlarged negative must be produced. The latter option is the practical choice for most of us.

A number of years ago I acquired a small supply of Kodak 2575 Direct Positive Duplicating Film. This is a continuous tone film of moderately high contrast which can be handled under ordinary safelight and which, when exposed in an enlarger and processed in Dektol, produces a copy negative. That is, a negative can be enlarged in one step to produce a larger negative. All of my experiments with Cyanotype has been using this material, and I recommend it.

An alternative is to enlarge a negative on conventional film. If I were to do this, I would first contact print the original camera negative (35mm or 6x6) to produce a film positive, and then enlarge this to produce a large negative. This would be more economical.

Litho film could be used instead of conventional negative film. Of course, litho film has very high contrast and the resulting prints will contain only the extremes of the tonal scale--bright highlights and deep shadows. However, starting with litho film might make sense for someone who is already experimenting with high contrast images and who wants to try Cyanotype without investing in another special emulsion.

Enlarged negatives can also be created directly from slides. In this case, only one step is required--a contact positive is not needed. However, one must recognize the spectral sensitivity of the film used to make the large negative will respond naturally to the colors in the slide with the result that the tonal range of the final image may be distorted.

Paper:

The other element is printing paper, and this is strictly do-it-yourself since commercial papers are not available. Home-sensitized paper is often an obstacle in experimental processes, but for Cyanotypes, sensitizing paper is neither hard, messy, nor very dangerous.

I have found that for Cyanotypes, I prefer a paper with a distinct texture. For this reason, I use a fairly heavy "cold press" water color paper which has a rough texture on the felt side. I buy the paper in a nearby hardware/art store in pads of twenty sheets--which works out at about 20 cents a sheet.

Many references on Cyanotype recommend sizing the paper before sensitizing it, and then talk at length about boiling Knox gelatin or Argo starch. The thought of that hassle caused me to try Cyanotypes on unsized paper, and I have found the results to be acceptable. Later I discovered spray starch which does just as good a job as the boiled variety but with much less effort. If you choose to size your paper, this is the way to go.