Printing a cyanotype on a t-shirt means fixing a fern, a silhouette or a photo turned Prussian blue onto a garment, using nothing but the sun. A t-shirt adds its own constraints, two layers of fabric lying on top of each other and a life that will include the washing machine. This page follows the process step by step for this specific case, and refers you to our guide to cyanotype on fabric for the underlying method.
A useful reminder before you begin: cyanotype works with sun and water, without a darkroom, through two iron salts that turn blue under ultraviolet light. If the process is still new to you, the reference guide to cyanotype lays the foundations before you tackle textiles.
Choosing and preparing the t-shirt
Everything starts with the material, and the rule is clear-cut: you need a t-shirt in natural fibres, preferably one hundred per cent cotton. Polyester and blends that are too synthetic do not hold Prussian blue, which comes away at the first rinse, so a t-shirt with sixty per cent cotton will give a dull result.
Cotton is also the most forgiving fibre among textiles, and the comparison of cotton, linen and silk details the clear blue it gives compared with other natural cloths. A white or ecru t-shirt offers the cleanest blues, and the details of fibres and fabric weights are covered on the page about which fabric to choose for cyanotype.
A new t-shirt is not ready to use as it is, because it almost always carries sizing, a factory finish that smooths the fibre and stops the solution penetrating. The step that deals with this is simple: wash the t-shirt in hot water without fabric softener, since softener also leaves a film that seals the fibre, then let it dry completely before sensitising.
Sensitising the garment
Once the t-shirt is clean and dry, you make it light-sensitive by applying the mixture of the two iron salts, in equal parts according to the recipe. Do this away from the sun, under the light of an ordinary bulb, which gives off too little UV to expose the solution.
What is specific to the t-shirt is its two layers: front and back touch, and the solution passes easily through cotton. So slide a piece of cardboard or a thin board inside the garment, under the area to be printed, so that the solution does not soak into the back. Then spread the solution with a wide brush or a foam applicator, criss-crossing your strokes and going slightly beyond the edges of the future design.
Cotton absorbs more solution than paper, so allow more and spread it well to avoid dry patches that will come out pale. The sensitised t-shirt then dries flat and away from the light, with the cardboard left in place, until it is completely dry to the touch, because damp fabric sticks to the negative and gives a blurred contact print.
- Wash the t-shirt in hot water without fabric softener, then let it dry completely.
- Slide a piece of cardboard or a thin board into the garment to protect the back.
- Spread the solution with criss-cross strokes, then leave it to dry flat, away from the light, with the cardboard in place.
A board slipped inside the t-shirt protects the back before you prepare the side to be printed.
Exposing the t-shirt to the sun
On the coated, dry area, lay out whatever will draw the image: a negative printed on transparency film, objects, or plants in direct contact. A fern frond, a grass stem or a piece of lace blocks the UV and prints its silhouette in a light tone on a blue background.
Contact is the tricky part, because jersey is supple and stretches out of shape. Stretch the t-shirt flat over the board slipped inside, then press the objects under a clean sheet of glass so that they touch the cotton over their whole surface; otherwise light creeps under the edges and blurs the outlines. Glass is almost essential on a supple garment, whereas paper is easier to manage.
Then take everything out into the sun. Timing follows the same rules as on paper, from a few minutes in full summer sun to several tens of minutes in overcast weather, with no absolute figure, cotton changing a little more slowly because it carries more solution.
The reliable sign is still the colour change on the surface, the coated area turning from pale yellow-green to a bronzed blue-grey once the exposure is sufficient.
On a supple garment, the glass holds grasses and lace flat until the surface turns a bronzed blue-grey.
Rinse, then fix for washing
Two separate steps finish the job, rinsing, which reveals the image, and fixing, which makes it last. As it comes out of the sun, remove the negative and rinse the t-shirt generously in clean, cold water until the water runs clear. This rinse removes the unreacted iron from the protected areas, which return to the white of the t-shirt, while the insoluble Prussian blue stays attached to the fibre.
Because a t-shirt is made to be washed, this step is more demanding than for a decorative frame: you fix the design with mild acid baths and a precaution for the first wash, so that it holds up wash after wash. The groundwork starts with the rinse, long and patient, until the residues are completely removed before any drying.
Then leave the t-shirt to dry flat in the shade; the blue deepens as it dries and over the following twenty-four hours until it reaches its final shade, darker than the one you see straight out of the rinse.
So only judge the colour once the fabric is completely dry. For future washes, turn the garment inside out and wash it in cold water with a mild, non-alkaline soap, ruling out alkaline detergent and bleach, which attack Prussian blue.
Pitfalls specific to t-shirts
The most common fault is a design that has bled through, the solution having soaked through to the back for lack of cardboard, or the blurred outline of a negative poorly pressed against the supple jersey.
Next comes a design that fades in the wash, which is almost always down to underexposure or an initial rinse that was too short, and which two steps put right: expose until the surface turns clearly bronze, and rinse until the water is perfectly clear.
For sensitising, there are two equally valid routes. You can prepare the two iron salts yourself from potassium ferricyanide and ferric ammonium citrate powders, following the cyanotype recipe, an economical route if you print in quantity. Potassium ferricyanide has low toxicity at the amounts used in the process, but it can release cyanide on contact with an acid, or under UV light when in solution.
To get started, the Sténoflex cyanotype kit contains the two salts and the pipettes for your first prints. Either way, choose a cotton t-shirt according to these principles.
Éric Marais — Photographer, author of two books on pinhole photography (published by Pearson) and creator of the Sténoflex. He has run introductory workshops in alternative photography, from pinhole to cyanotype, from the very beginning.