It started as a mistake, transformed workflow for architects, and revived Japanese print-making.
Created as a result of mixing blood, potash, and iron sulfate while trying to make red cochineal dye, Prussian blue was announced officially in 1710.
Paper covered with ammonium ferric citrate plunged into potassium ferricyanide turned Prussian blue and preserved the image of objects set on top of the paper in the process. And thus the “cyanotype” was born.
From there, architects found these “blue prints” useful to make copies of one drawing. Sound familiar?