Cyanotype is a photographic process invented in the 19th century. It allows the creation of unique prints without a camera, using sunlight.

A specimen – object, plant – is placed on a sheet of paper coated with a photosensitive solution and exposed to sunlight. The result after rinsing with water? A negative print.

The elements arranged on the sheet stand out in white against a deep blue background, known as Prussian blue.

To get started, here is a list of the equipment you will need:

• thick paper , capable of withstanding rinsing with water
• a mixing kit for photosensitive solution (ferric ammonium citrate and potassium ferricyanide)
• a wide brush to apply the solution evenly to the paper and a glass jar, like a jam jar
• a glass or plexiglass panel to hold the plants in place during the exhibition
• clothespins and a rigid support to stabilize the different layers when exposed to the sun

and of course,

• Plants : flowers, leaves or any plant element that you wish to immortalize

Tip : you will find on the eshop a kit with all the necessary equipment , including the mixing kit for photosensitive solution, to create your cyanotypes (without the plants).

1. Preparing the support

In the darkest room possible:

• Prepare the photosensitive solution: add water to each bottle (the one with the ferric ammonium citrate powder and the one with the potassium ferricyanide) to create a solution. Shake each bottle well to ensure the powders are dissolved. Pour the same proportion of each solution into the glass jar and mix them together.
• Dip the brush in the solution and apply it to your paper, ensuring an even distribution.
• Cover the paper to keep it in the dark and allow it to dry completely (for example, you can leave it to dry in a cardboard box).

2. Composition of your botanical image

• When the paper is dry, place it on a rigid support , such as a cardboard sheet.
• Arrange your plants carefully on the sheet
• Cover your composition with the glass or plexiglass panel.
• Hold the different layers together tightly (cardboard, paper, plants, glass panel) using clothespins.

3. Sun exposure

• Place your composition in direct sunlight for 5 to 20 minutes, depending on the light intensity. The stronger the light, the shorter the exposure should be.

4. Development of the cyanotype

• Once the exposure time is up, when the paper turns a grey-brown, lift the glass frame, remove the plants, and rinse the sheet under cold tap water (or immerse it in a container of water) to reveal the characteristic blue of the print. Then, let the sheet air dry.