Why Cyanotype Printing is the Trendiest Way to Make Sun-Art Prints

Cyanotype is one of the most accessible ways into camera-less photography: you need light-sensitive chemistry, sunlight, water, and objects to block the light. Every print is a one-off, because it records the exact shadows cast on the paper at that moment. The process is forgiving enough for a first-timer and cheap enough to start under $20, which is why it keeps resurfacing in craft and print circles nearly two centuries after it was invented. Cyanotype is also genuinely archival when processed correctly, so the prints last.

What cyanotype actually is

Cyanotype is a photographic printing process built on two chemicals: ferric ammonium citrate and potassium ferricyanide. Each is dissolved in water as a separate stock solution, then mixed in equal parts (one to one) just before use. Brushed onto paper or fabric, the mix forms a light-sensitive coating that dries a dull yellow-green. Under ultraviolet light — sunlight or a UV lamp — the iron compounds react and convert to an insoluble Prussian blue. Anything that blocks the UV, such as a leaf or a cutout, leaves that area unreacted and pale. A rinse in water washes the unexposed chemistry away, fixing the image and deepening the blue. The result is a white-on-blue photogram with no camera involved.

The two stock solutions keep for months stored separately in dark bottles, but once combined the sensitizer is best used within a few hours. Mix only what you need for a session. This is also why every step before exposure happens away from UV: stray sunlight will start the reaction and fog the coating before your objects ever go down.

A short, real history

The process dates to 1842, invented by Sir John Herschel, an English scientist who also coined the words "photography," "negative," and "positive." Its most influential early practitioner was the botanist Anna Atkins, who used cyanotype to record plant specimens as photograms. Her 1843 volume, Photographs of British Algae: Cyanotype Impressions, is widely regarded as the first book illustrated with photographic images — sun prints of seaweed made more than 180 years ago. Engineers later adopted the same chemistry for reproducing technical drawings, which is where the term "blueprint" comes from.

Why it suits beginners

• Minimal equipment — chemicals, paper, sun, and water; no darkroom required.
• Low cost — a starter kit runs under $20, and pre-coated paper lets you skip mixing entirely at first.
• Forgiving — uneven coats and partial exposures still produce usable, often striking, abstract results.
• Everyday negatives — leaves, flowers, feathers, lace, keys, and paper cutouts all print well.
• Fast feedback — exposure takes minutes and the blue develops visibly in the rinse water.

Supplies you need

Gather cyanotype chemicals or pre-coated paper, a sponge or foam brush, and a tray or tub for rinsing. Use a heavy paper — watercolor stock at 140 lb (300 gsm) holds up to soaking far better than printer paper, which can pulp and tear. A sheet of glass or clear acrylic (an old picture-frame pane works) presses your objects flat for sharp edges and stops a breeze from shifting them. Collect the objects you want to print — anything opaque or semi-transparent creates contrast. Wear gloves: the chemicals are low-toxicity but stain skin blue for days.

Fabric works as well as paper and opens up totes, tea towels, and pillow covers. Use a natural fiber — cotton, linen, or silk — since the chemistry binds to plant and protein fibers but not to polyester. Pre-wash fabric to remove any sizing or finish that would block absorption, and iron it flat before coating. For crisp botanical prints, fresh flat leaves and pressed flowers register more sharply than bulky three-dimensional objects, which cast soft, graduated shadows.

Coat and dry the paper

If you are using a kit, mix the two solutions per the instructions — they usually arrive as powders to dissolve or liquids to combine in equal parts. Do the coating in a dimly lit room away from direct sun; indirect light from a small lamp is fine. A tungsten bulb or a standard warm LED is safe, since the sensitizer reacts to UV, not to ordinary indoor light. Brush an even coat onto the paper or fabric; visible brushstrokes add character and do not ruin the print. Roughly two teaspoons of mixed solution covers an 8 × 10 inch sheet — enough to saturate the surface without pooling. Then dry it fully in the dark — hang it in a closet or lay it flat in a drawer for 30 minutes to a couple of hours depending on humidity. A hair dryer on a cool, no-heat setting speeds this along. The coating is ready when it is touch-dry and an even yellow-green. Coating too thin gives splotchy prints, so aim for full, consistent coverage moving in one direction, then cross-hatching.

Expose and wash

Arrange your objects on the dry, coated sheet, lay the glass over the top, and set it in direct sun. Exposure varies widely with UV strength, so use this as a starting guide and run test strips for your conditions:

The exposed coating turns from yellow-green to a murky blue or bronze-gray — that color shift signals it is working. When the exposed areas look deep, move the sheet out of the sun, remove the objects and glass, and rinse under cold running water. The unexposed chemistry washes out and the Prussian blue intensifies as you go. Keep rinsing until the water runs clear with no yellow-green residue; a final five-minute soak in fresh water improves permanence.

Dry and store

Hang or lay the print flat to dry. The blue deepens further as it oxidizes in air over the next hours, so a print that looks light straight out of the water will darken to the signature Prussian blue. To speed that oxidation and reach full depth immediately, add a capful of hydrogen peroxide to the final rinse water; the blue jumps to its finished tone in seconds. For display, frame finished prints behind UV-protective glass; cyanotypes are lightfast enough to last decades but will slowly fade under prolonged direct sun.

Once the standard blue feels familiar, toning shifts the color. Soaking a washed, dried print in strong black tea or coffee stains the paper and turns the blue toward brown, purple, or near-black depending on time and tannin strength; a brief dip in a weak washing-soda solution bleaches highlights first for more contrast. Printers who want photographic images rather than photograms use a digital negative — an image printed onto transparency film and laid over the coated paper like an object — which turns cyanotype into a full contact-printing process.

Common mistakes and fixes

• Splotchy prints. Caused by an uneven coat. Brush in one direction, then cross-hatch for full coverage.
• Faded, pale blue. Under-exposure. Use direct sun, and on overcast days extend the time substantially; test strips find the right window.
• Gray, washed-out highlights. Over-exposure. Pull the print once the exposed areas hit a deep blue-gray and shadow shapes look defined.
• Blue-stained hands. Wear gloves when mixing and coating.
• Fading after weeks. Incomplete washing leaves residual chemistry. Rinse until the water is fully clear, then give a fresh-water soak.

With adult supervision the process is suitable for older kids as a science-and-art lesson in light and chemistry — gloves on, nothing near the mouth. Coat a sheet, gather a handful of leaves, and expose a test strip in your own light before committing a full print; a few minutes of testing is what separates a muddy first attempt from a crisp, deep-blue keeper.