For a cyanotype on watercolour paper, a student-grade cellulose paper is enough to learn with. Pure cotton offers a more even surface and lasts better over time: keep it for the prints you want to frame, give or keep. Then compare the weight on the label and choose at least 250 grams. A hot-pressed (satin) surface suits detailed negatives, a rough surface suits textured photograms.
Watercolour paper has become the standard support for cyanotype, because it survives the long final rinse where most papers fall apart. But not all watercolour papers are equal, and the first distinction lies in their fibre: cellulose from wood, or cotton.
This page compares cellulose and pure cotton watercolour papers: what their fibre changes in the result, how well they last over time, and choosing between a student-grade paper and a paper for a print you want to keep. The complete guide to cyanotype lays down the basics.
Cellulose and cotton in the water
Cyanotype soaks the sheet deeply. You coat it with the solution of the two iron salts, expose it, then rinse it at length in clean water to clear out the iron that has not reacted. What allows watercolour paper to hold up is its sizing, an agent that slows absorption and keeps the sheet intact once soaked.
On this common basis, the fibre makes the difference. Student-grade papers are made of cellulose and are suitable for cyanotype as long as the weight is sufficient. Papers known as rag papers (in French), or pure cotton, are made of long, stable cotton fibres that coat more evenly, which makes their surface more uniform once the print is rinsed and dry.
A test on an offcut lets you see how the paper holds up in the water.
What pure cotton brings to the blue
Pure cotton often gives richer blues and a more even surface, which shows both in flat areas of colour and in the finesse of the details. It is the material of fine watercolour papers, and it ages better, which matters for an image you want to keep.
The difference lies mainly in the evenness of the surface and in how well the print lasts over time. The formation of the blue, on the other hand, depends on the chemistry and the exposure, not on the fibre, so a well-chosen cellulose paper already gives a successful cyanotype.
When student-grade paper is enough
To learn the technique, a student-grade cellulose paper is more than enough. You make your first coating and exposure tests on it, make mistakes without regret, and understand the process before investing in a more expensive paper.
Keep pure cotton for the images that matter to you, the ones you want to frame or give, and for prints from detailed negatives where the evenness of the surface shows.
Spotting pure cotton and the weight on the label
On the label, look for the words cotton or rag, and a weight of at least 250 grams. A quality watercolour paper is generally neutral or slightly acidic, which suits the process, and the optional acid-free label is reassuring for the preservation of the print, because an overly acidic support can make the blue fade over time.
To the touch, a firm sheet that does not bend limply suggests it will hold up well in the rinse, whereas a thin, floppy paper that already cockles when dry suggests an uneven blue. A paper warps in the rinse when it is too thin or too lightly sized: soaked through, it cockles and can tear, hence the value of a thick watercolour paper.
The right paper for each use
To start with, a student-grade cellulose paper of good weight. For prints you want to keep, pure cotton. The surface is then chosen according to the image: hot-pressed for a detailed negative, rough for a textured photogram.
The cyanotype kit includes ten sheets of paper, along with the two bottles of iron salts and two pipettes, a useful point of comparison before choosing your own sheets. Once you have chosen your sheet, the guide to preparing cyanotype paper details the coating.
- To learn: a student-grade cellulose paper.
- To keep, frame or give a print: a pure cotton paper.
- For a detailed negative: a hot-pressed surface.
- For a textured photogram: a rough surface.
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.