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Why are blueprints blue?

Who Put the 'Blue' in Blueprint?

The story of the creation of Prussian blue has all the elements of a dark fairy tale. In 1704, an alchemist and a dye-maker shared a laboratory in Berlin, Germany. The former, Johann Konrad Dippel, sought to create a universal remedy -- one that treated everything from animal mange to human epilepsy -- by boiling hooves, horns and leather into a smelly elixir. The latter, a fellow named Diesbach, made batches of vibrant dyes. One day, as Diesbach simmered insects, alum, iron and sulfate to create a deep red, he added some potash borrowed from the alchemist's elixir and added it to his viscous mixture. This horrible brew created a blue as deep as the night sky.

After retracing the steps in the process, Dippel realized the potash contained ox blood that when mixed with iron sulfate caused a chemical reaction and turned a brilliant shade of blue. Unlike other blue dyes that were difficult to make and easily faded, this blue remained vivid.

Initially, Dippel called the color Berlin blue as a nod to his city of residence. Later, it was called Prussian blue because it was used to dye uniform fabric for the Prussian army. The color became both a symbol of aggression and a term of endearment because of the army's fierce battles and serendipitous interventions in conflicts like the Battle of Waterloo.

By the late 1800s, Prussian blue had found favor with Impressionist artists and Japanese printmakers. As the 1900s wore on, it became the hue of newspaper ink, typewriter ribbon and eye shadow. Scientists even discovered Prussian blue works as an antidote to heavy metal poisoning by acting as a magnet to attract and evacuate heavy metals from the bloodstream [source: Pendle].

Eventually, Prussian blue became as important for its practicality as its novelty, but not while John Herschel was alive to see it. It wasn't until five years of his death that blueprints were recognized as an inexpensive and simple way to reproduce architectural drawings [source: Granaham].