An Introduction to Photography Techniques: Cyanotype
Cyanotype is most commonly used for blueprints as the chemicals that are used react to create the signature blue hue. It was used as a cheap printing technique by engineers, and was used well into the 20th century. Cyanotypes are mainly printed on watercolour paper, but they can be printed on other non-pourous surfaces as well.
In a cyanotype, a blue is usually the desired color; however, there are a variety of effects that can be achieved. These fall into three categories: reducing, intensifying, and toning.
Reducing is the process of reducing or decreasing the intensity of the blue. Sodium carbonate, ammonia, Clorox, TSP, borax, Dektol and other chemicals can be used to do this. A good easily obtained reducer is bleach. Bleaching takes some patience. How much and how long to bleach depends on the image content, emulsion thickness and what kind of toning is being used. When using a reducer it is important to pull the cyanotype out of the weak solution and put the cyanotype into a water bath to arrest the bleaching process.
Intensifying is the strengthening of the blue effect. These chemicals can also be used to expedite the oxidation process the cyanotype undergoes. These chemicals are hydrogen peroxide, citric acid, lemon juice, and vinegar.
Toning is the process used to change the color of the iron in the print cyanotype. The color change varies with the reagent used. There are a variety of elements that can be used, including tannic acid, oolong tea, wine, cat urine, and pyrogallic acid.
How to Create a Cyanotype Effect it Adobe Photoshop
Article title:Cyanotype
Website title:En.wikipedia.org
URL:https://en.wikipedia.org/wiki/Cyanotype
