Cyanotypes were invented by Sir John Herschel in 1842, just a few years after the dawn of photography. Herschel was instrumental in many early photographic processes, as he also discovered the use of sodium thiosulfate as fixer, to make images on negatives and prints permanent. We still use this chemical today to ensure permanence in our analog film and print processes. As for the cyanotype image, it’s brilliant blue is the result of combining ferric ammonium citrate dissolved in distilled water, and potassium ferricyanide also dissolved in distilled water, for the emulsion coating on paper. When exposed to UV light, and processed in water, the emulsion turns a rich and vivid blue upon drying. 

Often considered a proofing method for skilled photographers, Anna Atkins, who many historians credit with being the first female photographer, was a botanist who used the process to create contact prints of her plant specimens in her studies. She self-published her first book of cyanotypes, Photographs of British Algae, Cyanotype Impressions, in 1843. Given the casual appearance of cyanotype images, and the relative safety of the chemistry, it became a go-to for many people to have their family pictures made in blue, creating it’s own charm and uniqueness.