How to Make a Cyanotype (and Get the Look Digitally)

How do you make a cyanotype?

To make a cyanotype, you coat paper or fabric with a mix of ferric ammonium citrate and potassium ferricyanide, let it dry in the dark, lay an object or a negative on top, expose it to UV light such as sunlight, and rinse it in water. Areas that got light turn Prussian blue; covered areas wash out to white.

If you don't have chemicals or sun, you can also get the blue-and-white look from a digital photo. Both routes are covered below.

What is a cyanotype?

A cyanotype is a photographic print made with iron salts instead of silver. It's one of the oldest photographic processes, and it's easy to recognize by its deep blue color.

The process was introduced by the English scientist Sir John Herschel in 1842. Soon after, the botanist Anna Atkins used it to record plant and algae specimens by laying them directly on coated paper, and her cyanotype books are among the best-known early uses. Later, the same chemistry was used to copy technical drawings, which is where the word "blueprint" comes from.

Today it's popular with artists, teachers and hobbyists because it needs no darkroom, works in sunlight, and uses inexpensive chemicals.

How does the chemistry work?

The sensitizer is two solutions mixed together: ferric ammonium citrate and potassium ferricyanide.

When UV light hits the coated surface, it reduces the iron in the ferric ammonium citrate from the ferric (Fe³⁺) state to the ferrous (Fe²⁺) state. That ferrous iron reacts with the ferricyanide to form Prussian blue, an insoluble blue pigment. The parts that didn't get light don't form it, and the unreacted chemicals wash away in water, leaving white paper.

That's why a cyanotype is a negative process: light makes blue, shadow stays white.

What you need

• The two sensitizer chemicals, or a ready-made cyanotype kit, which is the easiest way to start.
• Paper or fabric. Heavy, absorbent paper (such as watercolor paper) or natural fabric like cotton.
• A brush or foam brush to coat the surface.
• Something to print: flat objects like leaves and lace, or a negative printed on transparency film.
• A sheet of glass or a contact frame to press things flat.
• UV light: direct sunlight, or a UV lamp.
• A tray of water for rinsing.
• Gloves, and a dim room for coating.

Step by step: making a cyanotype

1. Mix the sensitizer. Combine the two solutions in equal parts, following your kit's or recipe's instructions. Mix only what you'll use, since the mixed solution doesn't keep long.
2. Coat the paper. In dim light, brush an even coat onto the paper or fabric. It will look yellow-green.
3. Dry it in the dark. Let it dry completely somewhere dark. Damp paper gives blotchy results.
4. Arrange your image. Lay your objects or negative on the dry coated surface and press them flat under glass. Anything that isn't in tight contact will print soft and blurry.
5. Expose to UV light. Put it in sunlight or under a UV lamp. Exposure time varies widely with the season, the time of day and the paper, from a few minutes in strong sun to much longer in weak light or under a lamp. Run a test strip first. The exposed areas usually darken to a grey-blue or bronze tone.
6. Rinse in water. Wash the print in cool water until the water runs clear and the white areas no longer look yellow. This removes the unexposed chemicals.
7. Let it dry. The blue keeps deepening as it dries and oxidizes over the next day or so. A brief dip in diluted hydrogen peroxide speeds that up, but isn't required.

What to print: easy first projects

• Leaves and pressed flowers. The classic photogram. Flat, thin specimens give the sharpest edges.
• Lace, feathers and cut-paper shapes. Semi-transparent materials print as lighter blues and show texture.
• Photos from a negative. Invert a photo, print it on transparency film, and contact-print it. The result looks like a real photograph in blue.
• Fabric. Tote bags, scarves and T-shirts in natural fibers can be coated and printed the same way.

Common problems and fixes

• Print is pale or washes out. Usually underexposed. Expose longer, or use stronger light.
• Whites look blue or muddy. Usually overexposed, or the paper was exposed to light while coating or drying. Coat and dry in dimmer conditions.
• Blotchy or streaky blue. Uneven coating, or paper that wasn't fully dry. Brush more evenly and wait longer.
• Blurry edges. The object or negative wasn't flat against the paper. Use glass or a contact frame.
• Fading over time. Cyanotypes can fade with long light exposure and can be damaged by alkaline materials like some detergents. Store finished prints out of direct sun.

A safety note: handle the chemicals with gloves, keep them away from food, and never mix potassium ferricyanide with strong acids, which can release toxic gas. Follow the safety sheet that comes with your kit.

How to get the cyanotype look digitally

A digital filter can't recreate the chemistry, but it can map the light and dark areas of a photo to the same blue-and-white palette. That's useful when you want the look for a poster, social post or mockup, or want to preview how a photo might read before printing a real negative.

Artgen's cyanotype filter does this with a fixed effect:

1. Open the cyanotype filter and sign in. Upload a PNG, JPEG or WebP image up to 5 MB, or click "Try a sample image".
2. Adjust Contrast (default 1.15) and Exposure (default 0).
3. Click "Convert image". After changing a setting, click it again to apply.
4. Compare with the original and download the image before you leave or refresh the page.

The tool maps tones from deep Prussian blue to pale paper. The same image with the same settings always gives the same result. It's free with sign-in, no credits needed.

Keep its limits in mind: it changes the tones of your existing photo. It doesn't remove the background, rearrange objects, or turn a photo into a contact-print silhouette. Images are scaled down so the longest edge is at most 512 px, and transparent areas become white.

Photos that work well: evenly lit images with visible midtones, such as leaves, architecture and portraits with clear lighting. Raise contrast gradually so fine details like leaf veins or facial features don't disappear into solid blue.

FAQ

**Who invented the cyanotype?

** Sir John Herschel introduced the process in 1842. Anna Atkins soon used it to make some of the first photographically illustrated books, of algae and plants.

**What chemicals do you need for a cyanotype?

** Ferric ammonium citrate and potassium ferricyanide, mixed in equal parts. A ready-made kit is the simplest way to start.

**How long do you expose a cyanotype?

** It depends on the light. It can be a few minutes in strong sun and much longer in weak light or under a lamp. Test strips are the reliable way to find out.

**Can I make a cyanotype from a digital photo without chemicals?

** You can get the look, not the physical print. A digital cyanotype filter maps the photo's tones to Prussian blue and white. Artgen's version is free with sign-in, no credits needed.