The short answer?
A really cool, simple, old school photography process that results in a blue and white colored print.
A longer answer…
A cyanotype is considered a form of alternative photography. It is a print made mostly on paper or fabric, I use fabric, that has been coated with light sensitive chemicals. The image or design of the cyanotype is created by placing objects or a photo negative on top of the paper or fabric. The places on the fabric that are in shadow or covered by the object (anywhere the sunlight is blocked) will turn white after it is developed. The areas exposed to the sun will turn blue. The blue is due to the color of the chemical ferric ferrocyanide also called Prussian Blue.
The exposure time can vary depending on materials, strength of sunlight, affect you want, etc. but once the fabric has been exposed you remove it from the sunlight and rinse it in a water bath. Regular house light is not strong enough to expose the image, it has to be UV light and sunlight works best. This is why cyanotypes are also called sun prints.
It is a really simple process and easy to do because it does not require a dark room. The process has been around for over a century, since the beginning of photography, and has been used for various things, including architectural blueprints, over time. Anyone can make a cyanotype including kids thanks to sun print or cyanotype kits like these paper ones by SunPrint or these fabric ones by @jacquardproducts. A super fun activity that is especially exciting when you dip the paper or fabric in the water and watch the big reveal as the colors change! It is also a great way to help understand the basic principles of photo development, something that is being lost in the digital age.
I also recommend the book “Cyanotype: The Blueprint in Contemporary Practice” by Christina Z. Anderson for an in depth look at both the process of cyanotype and to learn more about artists that are using cyanotype today.
Yours truly, Amanda Porter