Spotlight on colour: Prussian Blue


Prussian Blue
Prussian Blue, an intense blue pigment, has a high tinting strength and produces a range of hues from the palest tint to a deep blackish-blue. Winsor Blue is part of the Winsor & Newton ‘Winsor’ family of colours, created to replace less reliable colours such as the Prussian Blue of the 1700’s

Famous for being amongst the first modern synthetic pigments ever created, Prussian Blue was discovered by chance in 1704 by the German colour-maker Diesbach when he was creating a red lake pigment to use as a dye, using iron sulphate and potash. On this lucky occasion, the potash was contaminated with impurities in the form of animal oil and instead of a bright red, Diesbach produced a purple, which when concentrated, became a deep blue pigment. This accidental discovery provided a new alternative to the only permanent blue pigment available, Ultramarine (Lapiz Lazuli), which was extortionately expensive as it was mined in limited amounts in Afghanistan.

By 1710 Prussian Blue was being used by many artists in the Prussian Court, hence its name. The use of the pigment spread through Europe in watercolour and oil colour, used by artists such as Antoine Watteau and Jean-Baptiste Pater. It then spread globally as far as Japan, where it was used for Hokusai’s woodblock painting ‘The Great Wave off Kanagawa’ and ‘Thirty Six Views of Mount Fuji’. Since then, Prussian Blue has featured in the palettes of artists such as Monet, Constable, Gainsborough, L.S. Lowry and Picasso in his famous ‘Blue Period’.

Many of these historic paintings using Prussian Blue show its tendency to fade and become greyish over time. 

Winsor Blue was created as a stable and lightfast version to replace Prussian Blue. Winsor Blue was launched by Winsor & Newton in 1938. It comes from the phthalocyanine family of colours which were first chemically synthesized in the late 1920s. Many new synthetic organic pigments were being discovered around this time, however only three were universally accepted for their artist quality in the 1950s: Phthalocyanine Blue, Phthalocyanine Green and Alizarin Crimson.

Winsor Blue has many of the same properties as Prussian Blue including its intense richness of pigment, its transparency and great tinting abilities while being completely permanent and lightfast. It mixes very well with other colours and when thinned, makes a great glaze. It is a deep and intense blue which approaches black in mass tone and it is formulated to have either a red or green undertone leading to the variations of Winsor Blue (Red Shade); ideal for mixing ‘purples’, or Winsor Blue (Green Shade); ideal for mixing ‘greens’.