Deep, bold and intense, Prussian Blue is the first synthetic blue pigment to have ever been made. Discovered completely by chance, it quickly became popular as an exciting and much cheaper alternative to the only permanent blue pigment available at the time, Ultramarine. Used by artists like Watteau, Hokusai and Picasso, Prussian Blue has revolutionised the artist’s palette, ever since its happenstance invention.

It was by accident that Johann Jacob Diesmach invented Prussian Blue in 1704. The Berlin-based colourmaker had been attempting to create a red lake pigment to use as a dye. To do this, he was using iron sulphate and potash, and on this lucky occasion, the potash was contaminated with impurities in the form of animal oil. 

Instead of a bright red, it produced a purple. And when concentrated, it became a deep blue pigment. Mined in limited amounts in Afghanistan, deep-blue Ultramarine (lapiz lazuli) was extortionately expensive and often scarce. This accidental discovery therefore provided a new alternative to the highly prized colour, altering the canon of painting pigments for good. 

By 1710, Prussian Blue was being used by many artists in the powerful Kingdom of Prussia that ruled much of northeastern Europe, giving it its name.                                                                                 (Resouce: Winsor & Newton)