Making Your Own Cyanotype Emulsion

Cyanotype is one of the most accessible historic photographic processes: two iron-based solutions are combined, brushed onto paper, dried in darkness and exposed to ultraviolet light. A leaf, lace fragment, drawing or transparent negative placed on the coated surface blocks the light, leaving a luminous Prussian blue image after washing.

Making the sensitiser at home offers greater control than buying pre-coated paper. You can adjust the coating, work at different scales and combine botanical photography with drawing, collage or traditional printmaking. The process also rewards a patient studio routine, which is useful whether you are working in a spare room in Melbourne or preparing photographs for a community printshop in Brisbane.

Understand the chemistry

A basic cyanotype emulsion uses two stock solutions. Solution A contains ammonium ferric citrate, while Solution B contains potassium ferricyanide. When equal quantities are mixed, the resulting light-sensitive iron complex reacts with ultraviolet light and eventually forms the insoluble blue pigment known as Prussian blue.

Keep the two stock solutions separate until you are ready to coat paper. Stored independently in labelled, light-resistant bottles, they generally remain usable for a reasonable period. Once combined, the sensitiser becomes more vulnerable to light and should be used promptly. The exact colour can vary from deep navy to a softer blue depending on paper, exposure, washing and the strength of the ingredients.

This is a photographic process rather than an ordinary paint recipe, so accuracy matters. Use a digital scale, distilled or deionised water where possible, clean glassware and a measuring method that can be repeated. Small differences in concentration may produce charming variations, but inconsistent measurements make it difficult to diagnose weak or uneven prints.

Gather materials and work safely

For a small batch, obtain ammonium ferric citrate, potassium ferricyanide, distilled water, two amber bottles, disposable pipettes, a soft brush or foam applicator and acid-free paper. A cotton-based watercolour sheet, printmaking paper or heavyweight archival paper is usually more successful than ordinary office stock. Australian art suppliers often carry suitable 300 gsm watercolour and print papers, while large hardware chains may be useful for trays, gloves and clips.

Wear nitrile gloves, protect the bench and label every container clearly. Mix in a ventilated area, keep food and drink away from the workspace, and wash your hands after handling the chemicals. Potassium ferricyanide is not the same as free cyanide, but it should still be treated as a laboratory chemical. Never combine cyanotype chemistry with strong acids, as acidic conditions can release dangerous hydrogen cyanide gas.

Use dedicated equipment rather than kitchen utensils. Keep children and pets away from the drying and coating area, and store powders and solutions securely. If you are working in a shared studio in Sydney, Perth or Adelaide, follow the venue’s chemical register and disposal rules instead of assuming that domestic drainage is appropriate.

Mix the sensitiser

Prepare each stock solution separately in subdued light. A common starting point is to dissolve 25 grams of ammonium ferric citrate in 100 millilitres of distilled water for Solution A, then dissolve 10 grams of potassium ferricyanide in 100 millilitres of distilled water for Solution B. These quantities are a practical small-batch formula, but always check the supplier’s instructions because different grades and formulas may require adjustment.

Add the powder gradually to the water and stir until the liquid is as clear and even as possible. Ammonium ferric citrate can be slow to dissolve, so allow it time rather than using excessive heat. Mark each bottle with the chemical name, concentration, date and hazard information. Amber glass or opaque plastic helps protect the solutions from stray light.

When you are ready to coat, combine equal volumes immediately before use. For a test sheet, a few millilitres may be enough. Mix gently to avoid bubbles, then use the sensitiser within the session. If the liquid appears unusually cloudy, develops sediment or produces weak results across several papers, make a fresh batch rather than endlessly increasing exposure times.

Prepare paper for coating

Cut paper to the final size before applying the emulsion. Smooth, absorbent surfaces are easier to coat evenly, although a little texture can add a distinctive printmaking character. Very absorbent paper may need sizing with a suitable archival product, while some commercially sized watercolour papers can be coated directly after a small test.

Work under dim tungsten light or in a shaded room, avoiding direct sun and strong ultraviolet-rich lamps. Lay the sheet on a protected surface and apply a thin, even layer with a hake brush, foam brush or glass rod. Two light coats are often better than one heavy coat, but allow the first layer to dry before adding another.

Brush in one direction, then lightly cross-brush if necessary. Avoid saturating the paper, because puddles can dry with tide marks and muddy shadows. A large artwork may require a careful coating system and a controlled drying area; the scale and pacing of this approach can be seen in the process behind a large photographic project.

Dry the coated sheets in darkness or very low light until they feel completely dry. Use them soon after coating for the most reliable results, or store them flat in a lightproof envelope with a note of the coating date. In coastal Queensland, damp air can extend drying time, while a dry winter studio in Canberra may cause the surface to dry quickly and unevenly.

Expose images in Australian light

Place your dried sheet beneath a negative, plant specimen, stencil or other object. A sheet of glass or a contact-printing frame will keep everything flat. Transparent negatives work well for detailed photographs; opaque objects create silhouettes and delicate edge shadows. Leaves from a gum tree, banksia or paperbark can give the image a strong local character without requiring elaborate materials.

Ultraviolet levels in Australia can be intense, especially around Brisbane, Perth and inland areas. Start with a short test strip rather than assuming that a European exposure time will apply. Depending on the season, cloud cover, paper and negative density, a print may take anywhere from several minutes to half an hour in direct sun. Melbourne’s winter light can be softer and less predictable, while summer exposure near Sydney may progress rapidly.

Cover part of the sheet with card and expose the remaining area for a few minutes. Move the card and repeat until a stepped series of exposure times is visible. The unwashed image should usually appear bronzy, grey-green or slightly dull rather than fully blue. Washing reveals the final contrast, so do not judge the print solely by its colour under the sun.

For a more controlled studio setup, use a UV exposure unit with consistent lamp distance and timing. This is valuable when producing an edition or contract printing for another artist. Record paper type, coating amount, weather, exposure duration and washing method so that successful results can be repeated.

Wash and refine the print

Place the exposed sheet in a tray of cool running water or change the water several times. Wash until the yellow-green unexposed chemistry has left the paper and the highlights look clean. This may take five to ten minutes, depending on the paper and the strength of the coating. Handle the sheet gently because wet paper is vulnerable to creasing and abrasion.

The blue image often deepens as it dries and oxidises. Leaving the print in indirect daylight can encourage this change, although strong sun may fade some papers or alter the balance. Hydrogen peroxide diluted in water can accelerate the blue appearance, but it is optional rather than essential. Test it on a sample first, since rapid oxidation can make a delicate image appear harsher.

Avoid household bleach and strong acids unless you are deliberately carrying out a controlled chemical variation with full safety knowledge. If a print has yellow staining, the causes may include overcoating, insufficient washing, unsuitable paper or contaminated water. Keep a sample from each batch and compare results instead of changing several variables at once.

Once clean, dry prints flat between absorbent sheets or hang them carefully. Flatten fully dry work under weight if needed. Finished cyanotypes can sit alongside darkroom photographs, relief prints and installation elements, creating useful connections between camera-based and hand-coated image making. Artists interested in symbolic forms may also find inspiration in cosmic egg origins when developing motifs for layered cyanotype compositions.

Build a dependable studio routine

A successful home practice depends on repeatable tests rather than a single perfect exposure. Make a small paper comparison using two or three brands available in Australia, then note which one gives the best combination of blue density, clean highlights and manageable handling. Cotton rag paper may suit exhibition work, while a less expensive sheet can be useful for experiments and proofs.

Use a simple record sheet for every session. Include the formula, batch date, paper, brush, exposure conditions and washing time. This documentation is especially helpful when preparing work for a local exhibition, sending prints through Australia Post or collaborating with a community printshop where another person may need to reproduce your method.

• Start with small contact prints before coating large sheets.
• Test each new paper with a stepped exposure strip.
• Keep stock solutions separate, labelled and protected from light.
• Use local leaves, lace, drawings and photographic negatives as distinct source materials.
• Photograph successful tests beside their written exposure notes.

Cyanotype becomes more expressive when its technical limits are treated as part of the artwork. Uneven brush marks, paper edges, plant shadows and slight shifts in blue can all contribute to a handmade visual language. Begin with a modest batch, make several controlled tests and let the process guide the next print.