Potassium Ferricyanide is a red iron salt. Ferric Ammonium Citrate is a light-sensitive iron salt. Mixing Potassium Ferricyanide, Ferric Ammonium Citrate and water creates a cyanotype sensitizer that can be used to coat any natural fiber or porous surface, such as cotton, linen, silk, canvas, wool, paper, wood and leather to make detailed prints by harnessing the power of the sun. Use any object that casts a shadow: tools, toys, plants, leaves, stones, sand, string, lace, etc. Simply place the object on the sensitized surface and expose it to sunlight (UV). Use a digitally-printed photographic negative (an inverted black and white photo inkjet-printed onto a transparency) instead of an object to create full-resolution photographs on paper or fabric. Great for photographers, mixed media artists, printmakers, quilters, kids and more. The cyanotype process is easy, forgiving, quick, magical and fun.