by Gerald Boerner
Photography started out by coating metal or paper with light-sensitive solutions containing silver compounds. A little later, printing-out paper was introduced in which silver compounds were applied to the surface of paper previously coated with binding substances like collodion to which light-sensitive silver compounds were bound. Still later, these papers were coated with a third layer of clay-like substances (Baryte) to separate the impurity of the paper from the silver binding layer.
These produced printing papers that produced most of the prints of the 19th century. The problem was that the image on these papers was subject to contamination from unwashed silver compounds in the sensitized surface, from impurities in the paper, or from other chemicals used to “fix” the images. Therefore, toning processes with gold, platinum, selenium, and/or sepia to retard this degradation of the image.
This is where the alternative photographic processes summarized here come into play. Since they do not use silver to capture the latent image, the degrading of the image is avoided. Furthermore, They produced images that produced unique colors and, when processed properly, were relatively permanent. In fact, the Platinum prints were not only very resistant to fading, but they produced images with extended ranges of tones to produce extremely beautiful photographs. GLB
“You have to see a building to comprehend it. Photographs cannot convey the experience, nor film.”
— Arthur Erickson
“I don’t use composers. I research music the way I research the photographs or the facts in my scripts.”
— Ken Burns
“I don’t think I think when I play. I have a photographic memory for chords, and when I’m playing, the right chords appear in my mind like photographs long before I get to them.”
— Earl Hines
“I had already done a lot of research for Rough Riders, keeping notebooks and old photographs. Some of the books were antiques for that time period, with the covers falling off.”
— Tom Berenger
“There are particular images that I like. Allegro is composed of a series of still life photographs that has been put to speed. There is so much care that has gone into the composition of the cinematography.”
— Helena Christensen
“I’m exchanging molecules every 30 days with the natural world and in a spiritual sense I know I am a part of it and take my photographs from that emotional feeling within me, rather than from an emotional distance as a spectator.”
— Galen Rowell
“I was so impressed with the work we were doing and I was very involved ideologically in photography – that I arranged an exhibition at the College Art Association. The first exhibition I picked the photographs and so on and we had an exhibition in New York.”
— Ben Shahn
“I was pleased that two very disparate photographs, two images that each worked in their own way had appealed enough to other people for them to buy them. I was also relieved they weren’t the last ones purchased, and that they sold for a pound more than the frame was worth.”
— Graeme Le Saux
This posting is intended for the educational use of photographers and photography students and complies with the “educational fair use” provisions of copyright law. For readers who might wish to reuse some of these images should check out their compliance with copyright limitations that might apply to that use.
Early Photographic Techiques: Non-Silver Printing
The silver gelatin ‘monoculture’ has dominated photographic printing for nearly a century, but with each market-driven improvement the range of monochrome printing papers has become narrower. In the 1970s several artist-photographers began a rebellion against this hegemony by rediscovering some of the forgotten 19th-century processes which had lost the struggle for commercial viability. These ‘alternative’ printing materials generally require the hand coating of paper with solutions of light-sensitive chemicals. The aim is to broaden the spectrum of artistic photographic practice, ranging from the immaculately crafted platinum print with its exquisite ‘engraving black’ tones, on the one hand, to the painterly and sometimes flamboyantly coloured pigment images of gum bichromate, on the other. Alternative practitioners can select their materials and exercise manipulative control to a degree impossible with silver gelatin; or they can simply surrender, with wilful primitivism, to the serendipitous accidents of ill-defined photochemistry. Both holistic approaches can claim the satisfaction of being ‘true to one’s materials’.
The wider movement known as ‘alternative photography’ also encompasses the revival of early camera processes (all silver halide based) such as the ambrotype, calotype, daguerreotype, pinhole, tintype, and wet- collodion process, and the accompanying silver-printing processes such as salted paper and albumen. This account, however, is confined to the ‘non-silver’ methods of making the positive print, which may be subdivided into three main areas of practice, according to whether their photochemistry requires salts of iron, or chromium, or purely organic substances. Aesthetic and practical considerations tend to cut across these subdivisions, and the permanence of the image substance is an important re-emerging issue for archives and the fine-art market, where the photographic print is viewed as art object sui generis.
Compared with silver gelatin printing, the conspicuous drawback of alternative processes is their low sensitivity to light—about a million times less than that of silver bromide enlarging papers. Projection printing on alternative materials is impossible with the technology commonly available, so contact printing is the only way to achieve a sufficient throughout of light; the final image can therefore only be the same size as the negative. This disadvantage was largely responsible for the early commercial demise of alternative processes such as platinotype, in the face of a growing market for miniature cameras and bromide enlarging papers.
The light source employed must be intense, usually with some ultraviolet content: the technologists tend to opt for mercury lamps, but the mystics prefer to sun-print in the time-honoured fashion—especially if they enjoy a good climate. One compensation for the insensitivity is that a darkroom with safe lighting is not required. Another, less obvious benefit is that these imaging systems are in principle capable of extremely high resolution; for instance, modern technology has rediscovered dichromated gelatin as an ideal material for recording holograms.
With low-sensitivity processes the easiest options are lensless: to make photograms of botanical specimens, fabrics, clichés-verre, or even the human form. If prints are to be made from camera negatives, the modus operandi must entail either a large-format camera, or enlarged internegatives, made in the darkroom or—increasingly—by computer technology. Although many kinds of substrate can be coated with alternative sensitizers, the usual choice is a fine-art paper selected from those intended for watercolourists, etchers, and printmakers, with regard to tint, surface texture, weight, and sizing; a few papermakers have recently introduced products especially suited for alternative photographic processes. To discover that paper can be a beautiful material may be a pleasant surprise for viewers inured to the bland surface gloss or mechanical stipple of the commercial silver gelatin photograph.
The class of alternative processes depending upon the photo-reduction of iron (III) was invented by Sir John Herschel in 1842. ‘Ferric’ salts of iron (III) with the ‘vegetable acids’— especially citric, tartaric, or oxalic acids—are sensitive to light, becoming reduced to ‘ferrous’ salts of iron (II) on exposure to the ultraviolet.
Permanent images may be derived by further reaction of the product in three general ways.
- First, the iron (II) can reduce noble metal salts to the finely divided metal: platinum, palladium, and gold, giving rise to the platinotype, palladiotype, and chrysotype (or aurotype) processes; these are archivally permanent. Silver images can also be made by this indirect means; the processes called argentotype, argyrotype, brownprint, kallitype, sepiaprint, and vandyke, despite the variety of names, are all similar in principle, and have inferior prospects of permanence.
- Second, the iron (II) photoproduct may be reacted with potassium ferricyanide to give the powerful pigment Prussian blue (ferric ferrocyanide). Called cyanotypes, these blue images endure well, provided they are protected from alkali and excessive light. The third possibility is to couple the residual iron(III) with gallic or tannic acid, making iron-gall ink, the chief writing substance since the Middle Ages. Important once for photocopying, these ferrogallate, positive-working processes are no longer used.
All these iron-based processes are characterized by unmanipulated printing procedures, although they may be variously toned. Some provide a printout image, which can be inspected as it builds up during the exposure, using a hinged-back printing frame to retain registration. The need for test strips is thus avoided. Printout processes have the added benefit of being self-masking, a property which accommodates a long density range in the negative and yet is non-critical in exposure time. Having no colloidal binder layer, the prints on plain paper are totally matte, so the viewer experiences no reflective surface glare from the illumination. The image substance is embedded in the surface fibres of the paper sheet, which may be attractively textured, and is always sympathetic to retouching or overpainting.
The so-called pigment processes, invented by Poitevin in 1855, depend on the light-induced oxidation of organic matter by chromium(VI) in a soluble dichromate, which is itself reduced to chromium(III), a substance that causes hardening of a layer of water-soluble colloid, such as gelatin, gum acacia, casein, glue, or egg albumen, to render it locally insoluble where the light fell. Images are made visible by including a permanent pigment in the binder layer. Processes employing the light-hardening of dichromated colloids include gum bichromate, and the carbon process and its variants (e.g. Artigue, Fresson). A related group of processes employ dichromate as a bleach (or oxidant) for a silver gelatin image, replacing the silver locally with hardened gelatin, which can then selectively absorb oily printers’ inks, as in the bromoil, oleobrom, carbro, ozotype, ozobrome, and oil pigment processes, where the use of a silver gelatin paper enlargement provides a very convenient starting point. The appeal of these processes lies in the extensive manipulation that is possible with the hardened colloid matrix—in the first group, the image is developed controllably by physical removal of colloid-bound pigment, in the second, by the application of oil-based ink with brush or roller.
Direct photo-decomposition of certain coloured organic substances, natural or synthetic, has been employed since the earliest days of photography. In 1839 Herschel introduced his anthotype (or phytotype) process, involving the light-bleaching of dyes (anthocyanins) extracted from crushed flower petals; although such images cannot be fixed, a few of Herschel’s still survive today. The photo-decomposition of unstable diazonium compounds, together with their coupling reactions to form synthetic azo-dyes, gave rise to the diazotype, Feertype, and primuline processes, which found application in photocopying. Recently, modern photopolymers have been employed as binders for pigment images, as in Perera’s Heliochrome process.
Cyanotype is a photographic printing process that gives a cyan-blue print. The process was popular in engineering circles well into the 20th century. The simple and low-cost process enabled them to produce large-scale copies of their work, referred to as blueprints.
Two chemicals are used in the process:
- Ammonium iron(III) citrate
- Potassium ferricyanide.
In a typical procedure, equal volumes of an 8% (w/v) solution of potassium ferricyanide and a 20% solution of ferric ammonium citrate are mixed. This mildly photosensitive solution is then applied to a receptive surface (such as paper or cloth) and allowed to dry in a dark place. Cyanotypes can be printed on any surface capable of soaking up the iron solution. Although watercolor paper is a preferred medium, cotton, wool and even gelatin sizing on nonporous surfaces have been used. Care should be taken to avoid alkaline-buffered papers which will cause degradation of the image over time.
A positive image can be produced by exposing it to a source of ultraviolet light (such as sunlight) with a negative. The UV light reduces the iron(III) to iron(II). This is followed by a complex reaction of the iron(II) complex with ferricyanide. The result is an insoluble, blue dye (ferric ferrocyanide) known as Prussian blue.
Upon exposure to ultraviolet light (such as that in sunlight), the iron in the exposed areas will reduce, turning the paper a steel-grey-blue color. The extent of color change is dependent on the amount of UV light, but acceptable results are usually obtained after 10-20 minute exposures on a bright, sunny day. The highlight values should appear overexposed as the water wash will reduce the final print values. Prints can be made with large format negatives and lithography film, or everyday objects can be used to make photograms.
After exposure, developing of the picture involves the yellow, unreacted iron solution being rinsed off with running water. Although the blue color darkens upon drying, the effect can be accelerated by soaking the print in a 6% (v/v) solution of 3% (household) hydrogen peroxide. The water-soluble iron(III) salts are washed away, while the non-water-soluble Prussian blue remains in the paper. This is what gives the picture its typical blue color.
The overall contrast of the sensitizer solution can be increased with the addition of 1% (w/v) solution potassium dichromate. Approximately 6 drops for every 2-ml of sensitizer solution.
When considering the cyanotype process the blue colour is usually the desired effect, however there are a variety of effects that can be achieved. The effects fall into three categories: reducing, intensifying and toning.
Reducing is the process of reducing the intensity of the blue. To achieve this you can use Sodium Carbonate, Ammonia, Clorox, TSP, Borax, Dektol and others. A good household material that is easily obtained is Sunlight laundry detergent. When using a reducer it is important to pull the cyanotype out of the weak solution and putting the cyanotype into a waterbath to arrest the bleaching process.
Intensifying is the strengthening of the blue effect. These reagents can also be used to expediate the oxidation process the cyanotype undergoes. These reagents are Hydrogen Peroxide, Citric Acid, Lemon Juice, and Vinegar.
Toning is the process used to change the colour of iron which gives the cyanotype its pigmentation change the color of the iron in the print cyanotype. The colour change varies based on what you use. There are a variety of elements that can be used including: Tannic Acid, Oolong Tea, Wine, Cat Urine, Pyrogallic Acid.
In contrast to most historical and present-day processes, cyanotype prints do not like basic environments. So it is not a good idea to store or present the print in chemically buffered museum board. This will cause the image to fade. Another unusual characteristic of the cyanotype is its regenerative behaviour: prints that have faded due to prolonged exposure to light can often be significantly restored to their original tone by simply temporarily storing them in a dark environment.
Cyantotypes on cloth are permanent but must be washed by hand with non-phosphate soap so as to not turn the cyan to yellow.
Van Dyke Brown
Van Dyke Brown is an early photographic printing process. The process was so named due to the similarity of the print color to that of a brown oil paint named for Flemish painter Van Dyck.
Printing with Van Dyke Brown requires the use of a large format negative in the size of the desired print, a suitable substrate for coating and subsequent printing, and a UV light source, either sunlight or suitable bulbs. The substrate can be almost anything that the solution will adhere to. Watercolor paper is a good first choice, but trickier substrates such as metal, glass or tile can be first ‘sized’ with gelatin or arrowroot to facilitate coating. The substrate is coated with solution under tungsten light, air dried, and coated a second time if desired for a stronger image.
The negative is placed on the thoroughly dried coated substrate, and is then weighted with a piece of glass. Frequent printers often use a printing frame to ease the checking of printing progress without disturbing the registration, or alignment, of the negative on the paper. These printing frames also ease the printing of a second coat over the same image.
The glass-negative-substrate ‘sandwich’ is exposed to a source of UV light. UV bulbs offer more control and consistency of light than sunlight, but at greatly increased cost. Standard daylight fluorescents produce some UV light, but printing times may be very long. A good starting point for printing time is to check a region of your photo that is very light but should still show some tone or detail (a highlight), and note how long it takes to register this detail, and print as long again. The latent image now appears, although flat and lacking substantial shadow tones.
Processing the Printed Image
The image must now be washed, or cleared, in several changes of water to remove soluble iron and silver compounds It is good practice to slightly acidify the wash water, as iron compounds are more soluble in acid. A pinch of citric acid, dab of vinegar or pineapple juice will do the trick. As the image soaks, white cloudy precipitate of silver chloride will appear from the reaction of silver nitrate with chlorine in the water. Continue to wash for a few changes of water after this cloudiness ceases to appear.
Fixing is best done with a weak, alkaline fixer of 5% sodium thiosulfate with a teaspoon of household ammonia per liter. The alkali slows the fixing process and prevents rapid bleaching of the image. Almost immediately, the tones of the image will change to a deep chocolate brown. Keep fixing until the whites appear clear; about 2 minutes, and finish with a second, clean fix if desired for thorough removal of salts that would fade the image. Use a fixer clearing bath of sodium sulfite to help remove residual fixer, and give the print an extended wash fitting the absorbancy of the substrate, around 30-45 minutes for absorbent papers, or 5-10 minutes for gelatin sized tile or glass.
Air dry the print without heat. High heat will change the color of the print to more neutral and weaken the shadows.
Observe precautions for handling chemistry. Know your tools. Wear gloves and goggles if in doubt.
Like many photo processes, VDB is based on the light sensitivity of a salt, silver tartrate, which gives it a unique color and scale.
Kallitype is a process for making photographic prints.
Patented in 1889 by W. W. J. Nicol, the Kallitype print is an iron-silver process. A chemical process similar to the Van dyke brown based on the use of a combination of ferric and silver salts. Many developing solutions can be used to give a different image color (brown, sepia, blue, maroon and black). Kallitype images generally have a richer tonal range than the cyanotype. These prints were popular in the 19th century, and then their popularity faded away. Sometimes known as "the poor man’s platinum print", when the image is toned in platinum or palladium the result is nearly chemically identical to a true Platinotype. It is believed that many Kallitypes were passed off as true Platinotypes and remain in collections as so. Kallitypes have had a reputation over the years as having poor archival qualities and often fading. When properly cleared, Kallitypes are completely archivable and will not fade. Toning with a metal such as gold, platinum, or palladium will give extra image permanence. Ferrous ions embedded in the paper as a result of poor clearing is the cause of the lack of belief in image permanence. This can be easily identified by a yellow stain in the highlights.
Unlike the silver print process, platinum lies on the paper surface, while silver lies in a gelatin or albumen emulsion that coats the paper. As a result, since no gelatin emulsion is used, the final platinum image is absolutely matte with a deposit of platinum (and/or palladium, its sister element which is also used in most platinum photographs) absorbed slightly into the paper.
In photography, palladiotype is a monochrome printing process, a rather obscure variant of the platinotype.
Due to the shortage of commercial paper and high cost, photographers experimented with palladium paper and platinum-palladium mixes. Platinum paper has continued in use until the present, interrupted only by the world wars.
The process was in use after World War I, because the platinum used in the fairly popular platinotype quickly became too expensive for use in photography. Photographers tried to replace the platinum with the much cheaper palladium which gave similar effects. The cost of this metal, however, started to rise too and eventually, around 1930 the process was abandoned in favor of more economical processes.
Characteristics of a palladium print, compared to a platinum print:
- A warmer tone;
- Easier to solarize (see: Sabatier Effect);
- Large tonal range, up to D= 2.1, thus requiring a contrast-rich negative for printing;
- Deeper blacks, with a higher maximum density;
- A softer image, with delicate highlights.
Background and biographical information is from Wikipedia articles on:
Wikipedia: Van Dyke Brown…
Wikipedia: Platinum Prints…
Web Sites and Blogs:
Answers.com: Alternative (Non-Silver) Photographic Processes…
Brainy Quote: Photography Quotes…