June 24, 2011

Cyanotype: An Overview



As I explore a photographic process, I will post brief summaries of its essential technical elements. These summaries are not meant to be comprehensive or to substitute for books that deal in-depth with these processes. They are more field notes for myself and might be useful for a quick lookup while working with these processes. Remember that many of these alternative processes have been around for a century and a half and more and they have evolved considerably over that time. Remember, too, that these processes were not originally meant to be used with silver or even digitally printed negatives as most modern practitioners of alternative photo processes do. There are endless variations of formulas and techniques rather than one simple "right" method as my quick overview might imply to the superficial observer. But hopefully these summaries will serve as a quick reference or encourage you to read and explore further.

History: The Cyanotype was first described by Sir John Herschel in 1842. Numerous variations on the original formula are available.

Negatives: Generally a density range of about 1.35-1.4 is okay. That is, many negatives meant for ordinary darkroom printing with diffusion enlargers can be used. I find slightly contrastier negatives with a range of about 1.5- to be more suitable when using vinegar instead of water as the developer.

Sensitizer: Solution A: 20% ferric ammonium citrate (green) solution
Solution B: 8% potassium ferricyanide solution
Store both solutions in separate bottles and mix 1:1 just before use. Solutions will keep indefinitely in sealed dark bottles. Bacteria that might grow on solution A can be filtered off.

Coating the Paper: Any non-buffered paper can be used with gelatin sizing if necessary. Alkaline environments will degrade Cyanotypes. Coat evenly with brush or glass rod under low tungsten light. Can be air dried or dried with mild heat.

Printing: Printing times can be fairly long. Check the highlights by opening the split back to see if they are a shade or two darker than you want in the print. They will lighten considerably in the wash. The shadows are not good indicators as they might begin to reverse during the printing out process.

Processing: Cyanotypes can be developed using water. But white vinegar gives slightly more midtone contrast, about a stop and a half more dynamic range and a sharper print. But vinegar tends to tint the highlights light blue instead of pure white. I have found a 1:1 mixture of white vinegar and distilled water to give the best balance between retaining highlights and a longer tonal range. Develop by agitating in a tray for 45 secs to one minute and then put in a running water wash for 5 minutes. Hang to dry. A 0.3% bath of hydrogen peroxide (1+10 sol of commonly available 3% hydrogen peroxide solution and water) just before the final wash will oxidize the print to a deep blue. This is not necessary as the print will slowly oxidize in the air as it dries, but the peroxide bath lets you see the final color at once.

Toning: Tea or coffee or tannic acid can be used to tone cyanotypes. Bleaching with a solution of one tablespoon of sodium carbonate (washing soda) per liter of water solution before toning is said to reduce staining effects but I have not yet found a satisfactory method to produce repeatable results while toning cyanotypes.

June 06, 2011

The Keepers of Light: Book Review


This book takes its subtitle - "A History and Working Guide to Early Photographic Processes" - quite seriously. It is as much a history of early photography as it is a practical guide to early processes. So, while most handbooks for these processes have a bit of history included for 'background' as a matter of course, Crawford dedicates the major chunk of the book to a detailed, sustained and quite insightful history of early photography. The practical guide to these processes is quite competent but it is almost an afterthought after the exhilarating tour-de-force of the first section of the book on the development of photography from its earliest days to well into the age of the silver gelatin print in the first half of the twentieth century.

I have always found most histories of photography to be quite tedious. They usually read like a long list of dates and developments and brief backgrounds of the persons associated with them. This approach is akin to the older sort of history as a narrative of the rise and fall of kingdoms and rulers - a history based around personalities and a more or less linear notion of progress. But Crawford takes a leaf out of newer historians who write social history not as a linear narrative but as a 'genealogy' of inter-related strands perpetually interacting with each other - 'history from below.' Of course, he isn't writing with the grand developments within academic historiography in mind, but his approach makes this a very apt comparison.

The Keepers of Light lays out the evolution of what Crawford calls the 'syntax' of photography. The first chapter uses the examples of traditional printmaking and painting very effectively to lay out what exactly constitutes a 'syntax' for a visual medium. The parallels to modern theories of linguistics and semiotics are unavoidable and Crawford uses them very effectively to illustrate his point that every visual medium has a basic 'vocabulary' and 'ordering pattern' which combine to produce a coherent 'meaning' for the observer. This can be constituted of the most basic elements like the direction and thickness of strokes in an etching or the overall formal and technical limits of a medium. And the syntax of a medium can emphasize particular elements like form, texture, tone etc at the cost of others. Crawford argues that even though photography is sometimes seen to be a medium without a syntax - a process that merely reflects the world and is therefore in a direct and 'natural' correspondence with it - in fact each particular photographic process is strictly governed by a syntax. Every detail of the process - the tone, the detail, the reproducibility, even the duration of exposure required or things like generic conventions contribute towards the syntax. Together they define the limits and possibilities of the medium, how it produces the photographic artifact and how we, as the audience, make sense of that artifact. If anything, the photographic process is so intimately tied up with technology that the limits and possibilities of the syntax must be confronted every step of the way.

Thus Crawford sets out to write a history of early photography not as a history of linear events, but as one of the evolution of the photographic syntax. Part I of the book, divided into 12 chapters, traces this evolution in terms of changing conventions, demands and technical challenges that forced nineteenth century photography to constantly develop and evolve. The result is a breathtaking history which makes the twentieth century or even the fast pace of recent change with the emergence of digital seem quite tame by comparison. In doing so, it returns the reader to the sense of awestruck wonder that the practitioners of photography or its first audiences and consumers might have felt. To capture a veritable image of the world on a sheet of paper - as if not made by man but by Nature herself - this is something the magical, awesome quality of which we have lost sight of. We with our oh-so-sophisticated cameras, our 51 point autofocus and our MTF charts - even those of us who think of ourselves as 'traditionalists', use older film cameras and obsess over the zone system and sharpness. All of this is mere trifle compared to the wonder - the very sorcery - of the crude image of Paris rooftops on Niepce's bitumen covered glass. And isn't that why so many try alternative processes? To discover a hint of that magic, the discovery of the new world, the first step on the moon? It is akin to the jaded business traveler ticking off his air miles discovering the struggle that went into man's conquest of flight - from the myth of Icarus to the Wright brothers.

And the syntax is not merely a thing-in-itself - a mere description of the technical boundaries of a process. It lives in and interacts with the world in a way an unilinear perception of 'progress' cannot grasp. Thus the Daguerrotype reigned supreme since its introduction in 1839 for a couple of decades. Technically it was capable of producing results that would satisfy the zone system or sharpness junkie of more than a century later. But there were both socio-cultural and technical demands that its syntax couldn't satisfy. Crawford traces how the more painterly rendering of the Calotype and other processes proved more pleasing to an age for which photography had not been established as a completely unique and independent medium and the reproducibility of negative images proved too strong a technical demand to resist. So the syntax moved on, it evolved, it responded to demands.

It is in conceiving of the history of photography as the history of this dialog between form and content, between demand and response that Crawford's approach is so refreshing and unique. It is full of insightful detail accompanied by vignettes and bits of humor that are all the more charming because they do not quite fit with Crawford's somber academic style. Consider for example, the following revelation: "Subjects in early daguerrotypes frequently sit with one hand supporting the chin. They look like deep thinkers: They were actually concentrating on not moving their heads" (9). Similarly delightful are his observations on the limitations imposed by technique and form on content: for example, the depopulated cityscapes in early long-exposure Calotypes, or how the exposure limitations of certain processes dictated the look of many early street photos. Amusing and astonishing, too, are vignettes about the crisis in egg supply when factories were consuming 60,000 or more eggs per day to coat albumen paper or the fact that there were studios in the 1860s churning out over 1,000 copies from a negative per day! All of this leads to a history of photography down to the period of dominance of the silver gelatin print that is truly novel in approach and eye-opening in detail.

I have spent most of this 'review' on Part I of the book. This isn't unintentional because that is the part I found most compelling. The other two parts constitute a practical guide to some of the major processes and techniques of preservation. They are chock-full of detail and great for anyone wanting to try it out, but there are relatively few illustrations and some of the materials and sources from this 1979 book have obviously fallen out of date. For a pure practical guide, perhaps more recent books like Barnier's or James' might be better, or even one of the many internet sources for quick summaries of processes. But Crawford's basic introduction to sensitometry (while a little advanced in that it tends to assume familiarity with conventional darkroom sensitometry) and technique is very helpful. In other words, buy another book if you want merely a DIY guide, but definitely read this book if you want a perspective that will change the way you look at photography - not only its past, but even its present.

Crawford, William. The Keepers of Light: A History and Working Guide to Early Photographic Processes. New York: Morgan & Morgan, 1979.