Spotlight on colour: Cerulean Blue


A pure blue pigment, Cerulean Blue is opaque and bright due to its highly refractive particles. This stable, inert pigment does not react to light or chemicals, making it permanent and invaluable for artists. It is an inorganic synthetic mineral pigment made by the calcination of tins salts and silica with cobalt sulphate.

For many years, finding a permanent blue pigment was a challenge for painters. Lapis Lazuli and Azurite were too expensive and rare to be mass-produced and Smalt, which had been used since the 15th century, was inconsistent in quality and permanence. In 1802 French chemist Jean-Louis Thenard discovered Cobalt Blue. This was a great advancement in blue permanent pigments, but remained highly expensive. In 1805 Cerulean Blue, a cobaltous stannate, was created from a new process which followed the discovery of Cobalt Blue, derived by heating tin oxides with cobalt.

Sold in Germany during the early 1800s, Cerulean Blue only became well known with its re-introduction into the English market in the 1860s, under the trade name Coeruleum. Derived from the latin ‘caerleus’ meaning ‘dark blue’ and ‘caelum’ meaning ‘sky’ or ‘heaven’, Cerulean Blue is often recommended for painting deep, bright skies.

Cerulean Blue quickly became a staple pigment for water colourists and oil painters in the late 19th Century. The Industrial Revolution was well under way and painters welcomed new synthetic pigments to extend their palettes. Cerulean Blue was adopted by the Impressionists and can be found in the sky of Monet’s La Gare Saint-Lazare, 1877.

Cerulean Blue is an ideal colour for landscape artists. It is a pure pigment that mixes well with other colours and variations of the colour are available in oil, watercolour and acrylic.