Multi colored cyanotypes

Cyanotypes are usually blue. Or toned into a sepia color. Filipe shows us how to get both blue and sepia into the same cyanotype.

Writer and photography / Filipe Alves

The cyanotype process is a great way to create monochromatic prints that show that wonderful Prussian blue, or, using tea and other chemicals: purple, and brown prints may be created. Although it has been used only as a single layer process: one coating, one exposure, one print.

Just as in the gum bichromate process, several coatings may be applied to the print, and as there are some different colors that can be achieved with the cyanotype process (not color splitting), a cyanotype can be made to reproduce a 2 or even 3 color print, using only cyanotype chemistry and a set of previously prepared negatives.

Ingredients for making a layered cyanotype

• Ferric ammonium citrate
• Potassium ferricyanide
• Tannic acid
• Sodium bicarbonate or other bleaching agent.

This method applies some of the principles of gum bichromate.

1A set of negatives, one for each color used, although color reproduction is quite limited, some creative effects can be achieved.

2Preshrinking (if you are worried about image alignment).

3Washing baths.

Preparing the cyanotype negatives

As the color range available in cyanotypes is quite limited, to create suitable negatives one should increase greatly the saturation of the image, so differences in color will be visible in the final image.

To get the channels CMY, try the multichannel mode in Photoshop. I use M for the Brown color, C for the Blue color and Y for the Yellowish color.

If you don’t want to worry about calibration curves, overexposure, or under exposure, you can apply a half tone screen to your negatives, it will decrease resolution but will make high contrast negatives that will result in all shades possible.

The colors

The cyanotype process does not really have much colors available.The basic color is the Prussian blue, bleaching it, a very light yellow can be achieved, and toning this yellow with tannic acid will result on a sort of reddish brown or a slightly different tone if pirogallic acid is used. Probably all other darker tones are just mixes of these three.

But the chemistry of this process, and the several baths used to change the appearance of the print force us to have the colors applied to the print in a specific order:

Making a two color cyanotype print – brown and blue

1Brown color
Coat the paper, expose with negative for the brown color, wash, apply toning bath, bleach the print, apply wash bath.

2Blue color
Recoat the paper, expose with negative for the blue color, wash.

Making a three color print – brown, yellow and blue

The 3 color print is in fact very hard to achieve, as the yellow is very sensitive to tannic acid and will easily become as brown as the brown layer, and it is of very light color.

1Brown color
Coat the paper, expose with negative for the brown color, wash, apply toning bath, apply wash bath.

2Yellow color
Recoat the paper, expose with negative for yellow color, wash, bleach the print (in this step, the toned component will become brown, and the other will become yellow), apply wash bath.

3Blue color
Recoat the paper, expose with negative for the blue color, wash.

Making a two color cyanotpe print – black and blue

1 Black color
Coat the paper, expose with negative for the black color, wash, apply toning bath, apply wash bath.

2Blue color
Recoat the paper, expose with negative for the blue color, wash.

Single color cyanotype print

This method is also useful to combine a higher contrast and lower contrast exposure and increase the dynamic range of the final print. When you’re happy with the result, you can bleach and tone as you like…

Washing the print is very important after toning or bleaching, or that effect will pass on to the next layer of the print.

Toning with tannic acid will give a reddish hue even to the unexposed highlights of the image, reducing the overall contrast and brilliance of the final image.

Filipe Alves is a Portuguese Architect and 3D artist. With a passion for photography, astrophotography and holography. See his website.