SO... WHAT ARE CYANOTYPES?
Cyanotypes are one of the oldest photographic printing processes in the history of photography. Cyanotypes were first invented in 1842 by astronomer and scientist John Hershel (the son of William Hershel, the dude who discovered Uranus), not as a form of photography, but as a way to reproduce notes (blueprints). Cyanotype wasn't used as a form of photography until 1843, when botanist Anna Atkins used the cyanotype process to create a photographic album of algae specimens.
What's distinctive about cyanotype is its shade of cyan blue, which results from its exposure to UV light. A solution of ferric ammonium citrate and potassium ferricyanide is painted/brushed over an area, and then objects are placed over the brushed-on solution. Objects can be anything - plants, flowers, bottles, paperclips, scissors - literally anything that has shape and opacity to block the UV light! The solution is then exposed to UV light, and the result is ferric ferrocyanide aka Prussian Blue. After the print is exposed, the excess solution is rinsed away so that none of it remains on the print, and the print darkens to its final product.
The cyanotype chemicals I use to print my designs are non-toxic and do not present any health or safety concerns. All excess cyanotype solution is thoroughly washed out prior to drying, selling, and shipping out :)