The luminous Prussian blue of a classic cyanotype holds a certain magic, a direct window into a process born in the earliest days of photography. But what happens when that signature blue isn’t quite enough, when your artistic vision calls for earthy browns, deep blacks, or subtle violets? This is where the fascinating world of cyanotype toning comes in. It’s a journey beyond the blue, transforming the very chemistry of your print to unlock a diverse palette of colours. Forget simple filters; toning is a hands-on, slightly unpredictable, and deeply rewarding way to alter your cyanotypes fundamentally.
Toning isn’t about adding a layer of colour on top; it’s about chemically changing the iron compound (Prussian blue or Turnbull’s blue) that forms the image. Most toning processes involve two key stages: first, a partial or complete bleaching of the blue, followed by introducing a toning agent – often a tannin or other chemical – that reacts with the remaining or altered iron compounds to create a new colour. The delicate balance between how much you bleach and the strength and type of your toner is where the real artistry lies.
Chemical Safety is Paramount. While many common toning agents are household substances like tea or washing soda, others involve chemicals that require care. Always work in a well-ventilated area, wear gloves (nitrile is recommended) and eye protection, especially when handling alkalis like sodium carbonate or ammonia, or powdered acids like tannic or gallic acid. Label all your solutions clearly and dispose of spent chemicals responsibly according to your local regulations.
Exploring the Toning Palette: Agents and Expected Hues
The beauty of cyanotype toning is the sheer range of possibilities, often achievable with surprisingly accessible materials. Let’s delve into some popular methods for achieving different colour shifts.
Achieving Earthy Browns and Rich Sepias
Brown tones are often the first stop for printers looking to move beyond blue. They evoke a vintage feel and can add warmth and depth to images.
Tannic Acid (Tea and Coffee): This is perhaps the most popular and accessible toning method. Common black tea is rich in tannic acids. Simply brewing strong batches of black tea (use multiple bags per cup of hot water and steep for a long time) creates an effective toning bath. Coffee, especially strongly brewed or even instant coffee granules dissolved in hot water, works similarly due to its tannin content.
- Process: After thoroughly washing your cyanotype, immerse it in the strong, cool tea or coffee bath. Toning can take anywhere from a few minutes to several hours, depending on the strength of your brew, the paper, and the desired depth of brown.
- Result: Expect warm browns, ranging from light tan to deep chocolate. Black tea often gives cooler, more neutral browns, while coffee can yield warmer, reddish-browns. The paper itself might stain slightly, contributing to the overall tone.
- Variations: Experiment with different types of tea (green tea can sometimes yield grayish or olive tones, though less reliably than black tea for browns) or coffee roasts. Adding a pinch of washing soda (sodium carbonate) to the bath can sometimes speed things up or shift the hue, but test first.
Sodium Carbonate Bleach + Tannin Tone: For more control and potentially darker, richer browns, a two-step process using a bleach first is common. Washing soda (sodium carbonate) acts as a gentle alkali bleach.
- Process: Prepare a weak solution of sodium carbonate (start with 1 teaspoon per liter of water). Immerse the washed cyanotype, agitating gently. Watch carefully as the blue fades; you might pull the print when it’s significantly lightened but still visible, or bleach it almost completely for a stronger tone shift. Rinse thoroughly to stop the bleaching action. Then, immerse the print in your chosen tannin bath (strong tea, coffee, or a dedicated tannic acid solution – start with 1-2 tablespoons per liter of warm water).
- Result: This method can produce very deep, rich sepia and brown tones. Because you control the bleaching stage, you have more influence over the final density and colour.
Pursuing Deep Blacks and Muted Grays
Achieving a true neutral black from a cyanotype can be challenging but incredibly rewarding, lending prints a powerful, graphic quality.
Gallic Acid: Often used after a partial bleach, gallic acid (related to tannic acid) is known for producing cool, deep brownish-black or near-black tones.
- Process: Partially bleach the print using a very dilute alkali like sodium carbonate or even household ammonia (use extreme caution with ammonia – dilute heavily, maybe 1 part ammonia to 30-50 parts water, and work with excellent ventilation). Bleach until the blue lightens noticeably but is still strong in the shadows. Rinse very well. Prepare a gallic acid bath (start with 1-2 tablespoons per liter of warm water, dissolving thoroughly). Immerse the print and watch as the colour shifts.
- Result: Can produce some of the best near-black results, often with a cool, slightly purplish or brownish undertone depending on the bleach and paper. Requires patience and careful observation.
Strong Tannin Combinations: Sometimes, very strong, prolonged toning in concentrated tannic acid or specific tannin mixtures after a controlled bleach can push browns towards black, though often retaining a hint of warmth.
Conjuring Violets and Purples
Subtle violet and purple tones can add a unique, almost ethereal quality to cyanotypes.
Borax + Tannin: Using Borax (sodium borate) as the alkali bleach before a tannin bath is one route towards purples.
- Process: Prepare a Borax solution (try 1-2 tablespoons per liter of water). Bleach the print carefully, watching for the blue to shift – Borax can sometimes impart a slight purplish/grayish hue even during the bleach stage. Rinse thoroughly. Immerse in a tannin bath (tea or tannic acid solution).
- Result: Depending on the degree of bleaching, the type of tannin, and the paper, this can yield hues ranging from reddish-browns to mauves and muted violets.
Wine Tannin: Some practitioners specifically use wine tannin (available from homebrewing suppliers) for achieving certain purple or reddish-purple hues, often in combination with a gentle alkali bleach.
Experimenting with Greens and Olives
Green is perhaps one of the trickier colours to achieve reliably, often appearing as an intermediate stage or requiring specific chemical combinations.
Controlled Bleach + Weak Toner: Sometimes, very slight bleaching with sodium carbonate followed by a very weak or short immersion in a gallic acid or tannic acid bath can leave hints of the original blue interacting with the nascent brown/black tone, resulting in olive greens.
Ammonia Influence: Very dilute ammonia used as a bleach, followed by certain tannins, has been reported to produce greenish tones, but results can be highly variable and depend heavily on concentration and timing. Requires careful testing.
The Challenge of Yellows and Oranges
Achieving stable, vibrant yellows or oranges through direct chemical toning of the Prussian blue is notoriously difficult with commonly available and relatively safe toners. Historical processes sometimes used highly toxic chemicals (like lead compounds – absolutely avoid these!). Often, yellowish tones are the result of aggressive bleaching leaving only faint image remnants, which are then influenced by paper base colour or a very weak tannin toner. Experimenting with natural dyes like turmeric after bleaching might be explored, but colour permanence could be an issue.
Mastering the Toning Process: Step-by-Step
Regardless of the specific toner used, the general workflow shares common steps critical for success.
1. The Crucial First Wash: After exposing and developing your cyanotype (usually washing in plain water until the yellow unexposed sensitizer is gone and the blue deepens), ensure it is washed thoroughly. Residual iron salts can interfere unpredictably with the bleaching and toning baths, causing streaks or unevenness. A final wash in slightly acidified water (a capful of white vinegar in a tray of water) can sometimes help clear highlights, followed by another plain water rinse.
2. The Bleaching Stage (If Used): Prepare your chosen alkali bath (Sodium Carbonate, Borax, dilute Ammonia). Immerse the print fully and agitate gently and continuously for even action. Watch the print like a hawk! Bleaching can happen quickly. Pull the print slightly *before* it reaches the desired level of fading, as the action may continue for a few moments. Immediately transfer to a water bath.
3. Intermediate Rinse: Rinse the print very well after bleaching, using several changes of water. You need to remove all the alkali before introducing the acidic toner (most tannins are acidic). Failure to rinse properly can neutralize the toner or cause unwanted chemical reactions and stains.
4. The Toning Bath: Prepare your toning solution (Tea, Coffee, Tannic Acid, Gallic Acid etc.) according to your recipe or tests. Ensure powders are fully dissolved. Immerse the bleached (or unbleached, if toning directly) print. Agitate regularly. Toning times vary hugely – from minutes to hours. Colour development can sometimes be slow and subtle. Monitor progress by briefly lifting the print (let it drain) and observing under good light. Remember colours often appear darker when wet.
5. Final Wash: Once the desired colour is reached, give the print a final, thorough wash in running water for at least 10-20 minutes. This removes residual toning chemicals, which could cause fading or discolouration over time. Longer washing is generally better.
6. Drying: Gently remove excess surface water (a squeegee or blotting carefully can work, but be gentle with the wet emulsion). Air dry prints flat on clean screens or hang them carefully. Note that colours will likely shift and deepen slightly as the print dries completely. Be patient and judge the final colour only when fully dry.
Troubleshooting Common Toning Issues
Toning is an experimental process, and things don’t always go as planned. Here are some common problems and potential solutions:
- Uneven Toning or Streaks: Often caused by insufficient pre-washing, inadequate rinsing between steps, uneven agitation, or exhausted/contaminated baths. Ensure thorough washing and rinsing, constant gentle agitation, and use fresh solutions.
- Loss of Detail / Weak Image: Usually due to excessive bleaching. Bleach less next time, or start with a denser cyanotype print. Some toners can also slightly reduce fine detail.
- Colour Not Developing: Toner bath might be too weak, too cold, or exhausted. Try increasing concentration (within limits), warming the solution slightly (to room temperature or slightly above – avoid boiling), or mixing a fresh bath. Ensure proper rinsing occurred after any bleach step.
- Unexpected Colour Shifts: Water quality (pH, mineral content) can influence results. The type of paper used also plays a significant role – its sizing, fiber content, and buffered status can all interact with the chemistry.
Test, Test, Test! The single most important tip for successful toning is to run tests. Use small test strips or duplicate small prints to try different bleach times, toner concentrations, and durations before committing your main print. Keep detailed notes of your process (chemicals, concentrations, times, water temperature, paper type) and the results. This record-keeping is invaluable for achieving repeatable results and learning from experiments.
Beyond the Blue: Embracing Experimentation
Cyanotype toning opens up a vast field for creative expression, transforming a monochromatic process into one capable of producing a wide spectrum of subtle and rich colours. From the warm, accessible browns of tea and coffee to the deep, challenging blacks of gallic acid, each toning agent offers a different path. The key is methodical experimentation, careful observation, and a willingness to embrace the occasional happy accident. Don’t be afraid to try different papers, tweak concentrations, or even combine toning methods (with thorough rinsing in between). The journey beyond the blue is yours to explore, print by print.
