It begins with two chemicals (ferric ammonium citrate and potassium ferricyanide) which are seperately dissolved in water. You then mix them in the right ratio (in a room with little to no UV light, so no sunlight), and paint the liquid onto a medium, such as paper or fabric. Once the paper dries (again, in a room with artificial lights only), you can expose it with UV light. To make a picture or blueprint, first you'd make a transparent negative from a digital photo and print it on a printer transparency. Then lay the transparent negative on top of the paper, and secure it so nothing shifts during exposure. Ideally, a glass pane would then be put on top and something else on bottom (a board or book or another glass pane) to make sure everything is flush and tight, no air gaps. After all this, the whole glass-paper-transparency system is left in sunlight or under a UV lamp until the paper changes color and the photo is exposed (that part was sort of trial and error for me, to try to get the right exposure). Finally, the print is developed by soaking the paper in cold water several times, changing the water until the water stays clear, and then letting the print dry and oxidize. The oxidation step can be quickened by soaking the print in a very dilute bath of hydrogen peroxide. After the print dries, everything should be good! I believe cyanotypes are pretty stable once developed, so they shouldn't be affected much by UV.