What is cyanotype?
Short answer
Cyanotype is a photographic printing process that produces a distinctive cyan-blue print. Invented in 1842 by Sir John Herschel, the technique uses a light-sensitive solution of ferric ammonium citrate and potassium ferricyanide. When exposed to ultraviolet light, such as sunlight, the chemicals react to create an insoluble blue pigment called Prussian blue.
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How does the cyanotype process work?
The chemistry behind cyanotype relies on the reduction of iron salts when exposed to ultraviolet radiation. When the two primary chemical components are mixed, they create a light-sensitive solution that is applied to a porous surface, typically paper or fabric. Once the surface is dry, an object or a photographic negative is placed on top to block specific areas from light.
Upon exposure to sunlight or a UV lamp, the iron compounds undergo a photoreduction process. The areas exposed to light turn into a stable, water-insoluble pigment known as Prussian blue. The areas shielded by the object remain water-soluble. During the final washing stage, the unexposed chemicals are rinsed away with plain water, leaving behind a crisp, high-contrast white image against a deep blue background. This process is entirely chemical-based and requires no darkroom or expensive equipment.
What materials do you need for cyanotype?
To begin creating cyanotypes, you need a few basic supplies that are easily accessible. Most hobby stores or online art suppliers sell pre-mixed kits, though you can also purchase the raw chemicals to mix your own solution for greater control over the sensitivity and contrast of your prints.
- Cyanotype chemistry (ferric ammonium citrate and potassium ferricyanide).
- Heavyweight, acid-free watercolor paper or natural fiber fabric like cotton.
- A contact printing frame or a piece of glass to hold items flat.
- A tray for water washing.
- A soft brush or foam applicator for coating the paper.
- UV light source, such as direct sunlight or a dedicated UV exposure unit.
Ensure your workspace is dimly lit during the coating process. Even though the paper is not immediately sensitive to indoor ambient light, prolonged exposure will cause the chemicals to fog or turn prematurely blue, which degrades the final image quality.
How long does it take to make a cyanotype?
The duration of the cyanotype process depends heavily on the intensity of the UV source. On a bright, cloudless summer day, exposure times can be as short as 5 to 10 minutes. On overcast days or during winter, the process may take 20 to 45 minutes because the UV index is significantly lower.
- Prepare your paper by coating it in a dark room: 10 minutes.
- Allow the paper to dry completely in the dark: 1–2 hours.
- Expose the paper to UV light: 5–45 minutes depending on conditions.
- Wash the print in running water: 5–10 minutes.
- Final air drying of the print: 30–60 minutes.
If you are using a digital negative to print photographs, you may need to perform a test strip. This involves exposing small sections of your paper for different time intervals to determine the ideal duration for your specific light conditions.
Common mistakes when making cyanotypes
One of the most frequent errors beginners encounter is "fogging," which occurs when the sensitized paper is exposed to too much ambient light before the actual printing process begins. This results in a muddy, light-blue background instead of a clean white one. Always store your coated paper in a light-proof envelope or a dark drawer until you are ready to use it.
Another common issue is insufficient washing. If the yellow-green tint of the chemicals remains on the paper after the rinse, the print will continue to darken or develop spots over time. Ensure the water runs clear and that you soak the print for at least five minutes. Avoid using water with high alkaline content, such as softened water, as this can cause the Prussian blue pigment to fade or wash away entirely. If your water is heavily treated, consider using distilled water for the final rinse.
Why is cyanotype popular today?
Cyanotype has seen a resurgence in popularity among artists and educators because it is an accessible entry point into alternative photographic processes. Unlike modern digital printing, which is automated and intangible, cyanotype requires a physical connection to the environment. The process is tactile, unpredictable, and rewards experimentation with different textures, transparency, and layering techniques.
Beyond its artistic value, cyanotype is favored for its safety and environmental profile. It does not require toxic developers or fixers, making it a safe choice for classrooms and home studios. Its historical significance, popularized by Anna Atkins in the mid-19th century through her pioneering botanical studies, continues to inspire contemporary artists to explore the intersection of science and art. By using simple materials, anyone can transform everyday objects—from pressed ferns to lace or film negatives—into permanent, ethereal blue works of art that capture the passage of time and light.
Key facts
- Cyanotype is a camera-less photographic printing process that produces a distinctive Prussian blue image.
- Sir John Herschel invented the process in 1842, originally using it to reproduce notes and diagrams.
- The light-sensitive solution consists of a mixture of ferric ammonium citrate and potassium ferricyanide.
- Anna Atkins is credited as the first person to publish a book illustrated with photographs using this method.
- Sunlight or a high-intensity UV lamp is required to trigger the chemical reaction that creates the blue color.
- Prints are developed simply by rinsing the paper in plain water, which washes away the unexposed chemicals.
The bottom line
Cyanotype remains a fascinating intersection of science and art, offering an accessible entry point into historical photography. By coating paper with light-sensitive iron salts and exposing it to UV light, anyone can create striking monochromatic prints. Whether documenting botanical specimens or artistic negatives, this process rewards patience and experimentation, turning simple sunlight into permanent, deep blue images that have captivated creators for nearly two centuries.
People also ask
Is cyanotype printing dangerous to my health?
The chemicals used are generally considered low-toxicity, but they should still be handled with care. Wear gloves to avoid skin irritation and work in a well-ventilated area to prevent inhaling any dust from the powdered chemicals.
Can I use any type of paper for this process?
It is best to use heavy-weight, acid-free watercolor paper or cotton rag. Thin paper may disintegrate during the water-rinsing stage, and acidic paper can cause the image to fade or discolor over time.
Why did my print turn out pale or washed out?
This usually happens due to underexposure or insufficient UV light. Ensure you are exposing the paper during peak daylight hours or use a dedicated UV exposure unit to maintain consistency.
Can I print cyanotypes on fabric?
Yes, natural fibers like cotton, linen, and silk work exceptionally well with cyanotype chemistry. Ensure the fabric is thoroughly washed and dried before coating to remove any sizing or chemical finishes that might interfere with the process.
How do I store my cyanotype prints to keep them from fading?
Cyanotypes are sensitive to alkaline environments and prolonged exposure to strong light. Store them in a cool, dry place away from direct sunlight and avoid mounting them on acidic backing boards.
What is a common mistake beginners make when mixing the solution?
Many beginners mix the two parts of the solution too early, which causes the chemicals to lose their potency. Only mix the two stock solutions in equal parts immediately before you are ready to coat your paper.
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