by Gerald Boerner

  

JerryPhoto_8x8_P1010031 Most of us who have worked in the wet darkroom typically use silver gelatin prints to create the images from our negatives. We learn to use the enlarger, develop the film and paper, and show off our handiwork. And, in most cases, we produced some pretty good images.

What many of us have not explored are some of the older, alternative processes. We have Sir John Herschel to thank for many of these techniques. He experimented extensively with the light-sensitivities of many chemical. He found that sodium thiosulfate (hypo) would fix the image of the early prints after toning. He helped define the technology used to create platinum prints. And he developed the process of creating “blue prints”, called cyanotypes.

This is a neat technique that coats a porous paper, like watercolor paper, with a light sensitive mixture of iron compounds. A contact negative could then be placed upon this coated paper, after it dried, exposed to UV light in the outside sun, and then washed in water to creating distinctive prints in a beautiful blue color.

This same process can be used to create photograms as well as negatives (film or digital prints). It is fun, relatively inexpensive, and produces an attractive print.  GLB

    

Photography helps people to see.”
— Berenice Abbott

Photography can never grow up if it imitates some other medium. It has to walk alone; it has to be itself.”
— Berenice Abbott

Photography can only represent the present. Once photographed, the subject becomes part of the past.”
— Berenice Abbott

Photography deals exquisitely with appearances, but nothing is what it appears to be.”
— Duane Michals

Photography has the capacity to provide images of man and his environment that are both works of art and moments in history”
— Cornell Capa

Photography records the gamut of feelings written on the human face, the beauty of the earth and skies that man has inherited, and the wealth and confusion man has created. It is a major force in explaining man to man.”
— Edward Steichen

“Does not the very word ‘creative’ mean to build, to initiate, to give out, to act – rather than to be acted upon, to be subjective? Living photography is positive in its approach, it sings a song of life – not death.”
— Berenice Abbott

“Blessed be the inventor of photography! I set him above even the inventor of chloroform! It has given more positive pleasure to poor suffering humanity than anything else that has ”cast up” in my time or is like to — this art by which even the ”poor” can possess themselves of tolerable likenesses of their absent dear ones. And mustn’t it be acting favorably on the morality of the country?”
— Jane Welsh Carlyle

  

Note:
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.

GLB

  

Early Photographic Technique: Cyanotypes

Anna_Atkins_algae_cyanotype 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.

The English scientist and astronomer Sir John Herschel discovered this procedure in 1842. Even though John Herschel is perhaps the inventor of the cyanotype process, Anna Atkins actually brought this to photography. She created a limited series of cyanotype books that documented ferns and other plant life. By using this process, Anna Atkins is regarded as the first female photographer.

Unlike photographs set in silver, like in black and white photography, cyanotypes are using a solution of iron compounds.

The photograph can be taken with a camera, like a digital camera, and the resulting photo turned into a negative that can be used to make a cyanotype.

The basic cyanotype recipe has not changed very much since Sir John Herschel introduced it in 1842. However, some advances have been made by Mike Ware in what is referred to as the New cyanotype process. Ware’s cyanotype formula has less bleed, shorter exposure times and a longer density range than Herschel’s, but it is also slightly more complicated to mix and uses more toxic chemicals.

The Process

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.

Toning

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.

Long-Term Preservation

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 behavior: 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.

Cyanotypes on cloth are permanent but must be washed by hand with non-phosphate soap so as to not turn the cyan to yellow.

The Cyanotype Process at a Glance

The cyanotype process is simple. It can be done easily in a few steps:

Step 1… Mixing chemicals

The cyanotype is made up of two simple solutions.

  • Potassium ferricyanide and Ferric ammonium citrate (green) are mixed with water separately.
  • The two solutions are then blended together in equal parts.

Step 2… Preparing the canvas

  • Paper, card, textiles or any other naturally absorbent material is coated with the solution and dried in the dark.

Step 3… Printing the cyanotype

  • Objects or negatives are placed on the material to make a print. The cyanotype is printed using UV light, such as the sun, a light box or a UV lamp.

Step 4… Processing and drying

  • After exposure the material is processed by simply rinsing it in water. A white print emerges on a blue background.
  • The final print is dried and admired.

What you need

Before you start, get all the items you need together:

  • 25 grams of Ferric ammonium citrate (green)
  • 10 grams of Potassium ferricyanide
  • Water (distilled if possible)
  • Scale or measuring spoons
  • Measuring jug
  • 3 glass containers for mixing ingredients
  • Plastic spoons
  • Face mask (DIY style)
  • Goggles
  • Rubber gloves
  • Apron or old shirt
  • Newspaper to cover work surface
  • Cleaning cloth
  • Brushes or coating rod
  • Clothes pegs (plastic)
  • Washing line or rope (plastic)
  • Art paper or fabric for coating
  • Glass or a contact print frame
  • Sunshine or a UV light source

Mixing chemicals

Cyanotype is a very simple process. It involves treating a surface with iron salts that reacts to UV light. Wear a face mask and rubber gloves when working with chemicals. In this case, Ammonium ferric citrate and Potassium ferricyanide. Two separate solutions are made and then equal quantities of each solution is mixed together in a third container.

The Formula

This recipe makes approximately 50 8×10 inch prints. The cyanotype is made up of two simple solutions:

  • Solution A: 25 grams Ferric ammonium citrate (green) and 100 ml. water.
  • Solution B: 10 grams Potassium ferricyanide and 100 ml. water.

mf_proc_mixing_chemicals2


Step 1… Mixing the chemicals
  • Dissolve the chemicals in water to make two separate solutions.
  • Add Ammonium ferric citrate to water into one container and Potassium ferricyanide to water in another.
  • Stir with a plastic spoon until the chemicals dissolve.
  • Mix equal quantities of each solution together in a third container.

Unused solutions can be stored separately in brown bottles away from light, but will not last very long once they have been mixed. Dispose of any unused chemicals in a sensible and environmentally friendly way!


Note: Your work area

Your floors, carpets, walls, work surfaces, clothes and skin can be stained by the chemicals. Cover all possible areas, use rubber gloves and an apron or an old shirt to work in. If you have the space, choose an area where you can spread out. Ordinary light bulbs or tungsten light is safe to use, but UV light will affect your prints. Some fluorescent lighting may also affect your prints.

mf_proc_coating_w_brush

Step 2… Preparing the Canvas
  • Using a brush, simply paint the chemicals onto the material. Paper, card, textiles or any natural material can be used to print on.
  • Decide how big your print is going to be, and cut your material to size.
  • Make sure your working area is dimly lit, or lit with a low-level tungsten bulb.
  • Once the material is coated, leave it to dry in the dark.

Exposing a digital negative on cyanotype

Step 3… Printing the Cyanotype
  • Print a cyanotype by placing your negative (to reproduce a photograph) or object (to make a photogram) in contact with your coated paper or fabric. Sandwich it with a piece of glass.
  • Expose the sandwich to UV light. Natural sunlight is the traditional light source, but UV lamps can also be used. A photogram can also be made by placing items on the surface. Plants, decorative items or other objects can be used to create silhouettes or interesting shapes.
  • Exposure times can vary from a few minutes to several hours, depending on how strong your light source is or the season where you are printing.

You are now ready to reap the rewards for your efforts. The processing of a cyanotype is much simpler than almost any other type of print, especially the silver gelatin prints used today in most darkrooms.

Step 4… Processing and Drying

  • When the print has been exposed, process your print by rinsing it in cold water. The wash also removes any unexposed chemicals.
  • Wash for at least 5 minutes, until all chemicals are removed and the water runs clear. Oxidation is also hastened this way – bringing out the blue color.
  • The final print can now be hung to dry and be admired.

 

    

The Digital Negative for Cyanotype Prints

The first step in the making of a digital negative is to get an image into Photoshop. This can be a digital camera image, a negative scan, a slide scan, or a print scan. I have used all these sources for my images, the print of the Jaguar car on the left is from a colour slide scan.

The scan from either a colour or monochrome original should always be made in colour and at a resolution such that the final image size of the negative for printing ( mine are usually about 8×6) should have a resolution of 300ppi. Any other adjustments made within the scanner software will depend on your own experience, but I prefer to make these adjustments within Photoshop.

If you are working with a colour image this will need to be converted to black and white. I would sugest using the channel mixer, but leave the image in the RGB mode, do not convert to grayscale.

Colour management

color-settings-screen-shot

The above screen shot shows my photoshop colour settings

When you are satisfied with your image the next stage is to invert it to a negative and apply an adjustment curve.

One of the most common reasons why digital negatives fail to produce a good print is when the density range of the digital negative does not match the exposure scale of the alternate process being printed. This principle also applies to negatives made in camera and in the darkroom using film, in these cases exposure and development controls are used. For digital negatives an adjustment curve is applied in Photoshop, this curve is specific to the alternate process being printed, the negative substrate ie Pictorico film and the printer being used.This was one of the main points I learned from Dan Burkholders book " Making Digital Negatives for Contact Printing." The CD which comes with the book contains some ready made curves and the book explains how to modify these to suit your work flow. There are also some curves available for downloading from Dans website at www.danburkholder.com The system I am currently using for making my curves is Mark Nelsons " Precision Digital Negatives". This consists of a comprehensive manual on CD plus all the tools and curve calculators required and can be purchased at www.precisiondigitalnegatives.com.

curve-cyanotype-screen-shot

Cyanotype negative curve used for making the cyanotype
prints in this article. Curve generated using the precision
digital negative system

      

References

Background and biographical information is from Wikipedia articles on:

Wikipedia: Cyanotype… 
http://en.wikipedia.org/wiki/Cyanotype

Web Sites and Blogs:

Alternative Photography: Cyanotype: The Classic Process…
http://www.alternativephotography.com/wp/processes/cyanotype/cyanotype-classic-process

Michael Spedding Fine Art Photography: Digital Negatives 2…
http://www.msped.plus.com/alternate.htm

Brainy Quotes: Photography Quotes…
http://thinkexist.com/search/searchquotation.asp?search=Photography