How do you make a cyanotype?

What supplies do you need for cyanotype

To begin, you need a specific set of chemicals: ferric ammonium citrate and potassium ferricyanide. These are typically sold as powder kits that you mix with distilled water to create two separate stock solutions. You will also need high-quality, acid-free watercolor paper or heavy cardstock, as the coating process involves soaking the fibers. Avoid standard copy paper, which is too thin and lacks the durability to withstand the water bath required for final development.

You should also gather a few essential tools to ensure a clean application. A foam brush or a soft hake brush is ideal for applying the sensitizer evenly across the surface. A glass contact printing frame or a simple piece of clear acrylic held down by binder clips will keep your negatives or objects pressed firmly against the paper during exposure. Finally, prepare a dark, dry workspace, as the sensitized paper must be dried away from direct sunlight to prevent premature exposure.

How to prepare the paper

Mixing the chemicals is a straightforward process, but it must be done in low-light conditions to protect the solution. Combine equal parts of your two stock solutions in a small glass or plastic container just before you are ready to coat your paper. Once mixed, the solution is light-sensitive, so work in a room with blinds drawn or under low-wattage incandescent light. Avoid fluorescent bulbs, as they emit enough ultraviolet light to begin fogging your paper.

1. Measure equal parts of the two chemical solutions into a clean mixing vessel.
2. Place your paper on a flat, protected surface.
3. Dip your brush into the mixture and apply it to the paper using smooth, horizontal strokes.
4. Switch to vertical strokes to ensure full coverage and minimize brush marks.
5. Allow the paper to dry completely in a dark, cool place for at least one hour.

How long does it take to expose

The exposure time is entirely dependent on the intensity of the ultraviolet light available at the time of your session. On a bright, clear summer day, exposure might take as little as five to ten minutes. If you are working on a cloudy day or during the winter months, the exposure time can increase significantly, sometimes requiring up to thirty minutes or more. Because the process relies on UV rays, the strength of the sun is the primary variable you must monitor.

To determine the correct exposure, you can create a test strip by exposing several small sections of a scrap piece of sensitized paper for different durations. Watch for the color change: the paper will transition from a yellow-green to a dull, metallic bronze or gray-blue as it reacts to the light. If the highlights appear muddy or the shadows lack depth, you may need to adjust your timing. Always keep a log of your exposure times and weather conditions to help you refine your results over time.

How to develop and dry the prints

Once the exposure is complete, the development process is remarkably simple and requires only tap water. Immediately place the exposed paper into a tray of cool, running water. You will notice the unexposed chemicals washing away, leaving behind the characteristic Prussian blue image. Continue rinsing the paper for at least five to ten minutes until the water runs completely clear and no yellow residue remains.

After the initial rinse, some artists add a few drops of hydrogen peroxide to the water bath to intensify the blue color, though this is optional. Once the print is thoroughly washed, lay it flat on a clean screen or hang it with clips to air dry. As the paper dries, the blue color will continue to darken and deepen in richness. Avoid using a hair dryer or direct heat to speed up the process, as this can cause the paper to warp or the image to fade prematurely.

Common mistakes when making cyanotypes

One of the most frequent errors beginners encounter is uneven coating, which results in streaks or blotchy areas on the final print. This usually happens if the brush is too dry or if you apply too much pressure during the application. Another common issue is the use of tap water that contains high levels of chlorine or mineral deposits, which can affect the final hue of the blue. If your local water supply is heavily treated, consider using distilled water for the final rinse to ensure the best possible color clarity.

• Failing to keep the paper in total darkness while drying, which causes a foggy or muddy background.
• Using negatives that do not have enough contrast, resulting in a flat, washed-out image.
• Leaving the paper in the water bath for too long, which can cause the highlights to become slightly blue rather than stark white.
• Touching the sensitized paper with bare fingers, as oils from your skin can create permanent marks on the final print.