Colour Story: Cobalt Blue

Cobalt blue

Cobalt blue is a clean blue that is neither warm nor cold. With a moderate tinting strength, it is useful on the palette for muted colour mixes. It is semi-transparent in both Winsor & Newton Artists’ Oil Colour and Professional Watercolour. Cobalt blue deep, a unique, red shade cobalt blue is made by using cobalt zinc silicate.

Until the 19th century the best blue pigment available to artists was ultramarine. Laboriously ground from lapis lazuli, a semi-precious stone mined only in distant Afghanistan, the prohibitive cost of this pigment prompted the Napoleonic administration to find an alternative. The chemist Louis Jacques Thénard was commissioned by the French interior minister, Jean-Antoine Chaptal – himself an industrial chemist – to develop a synthetic substitute for ultramarine.

Lapiz Lazuli embedded in rock. Geert Pieters / Unsplash
Lapiz Lazuli embedded in rock. Geert Pieters / Unsplash


Thénard knew the famous Sèvres potteries used salts containing cobalt (smalt) to produce their blue glazes, and in 1802, from a mix of cobalt salts and alumina, he produced a pigment called cobalt blue. With a purer tint than Prussian blue, it was immediately taken up by artists. In fact, cobalt blue sometimes is called Parrish blue, after the artist Maxfield Parrish, who made famously intense blue skyscapes using this colour.

In 2007, Winsor & Newton celebrated 175 years of colourmaking and to mark the occasion Smalt (Dumont's Blue) watercolour was reintroduced as a limited edition colour.

Smalt is a bright variation on cobalt blue, made from the ground pigment of cobalt glass used in classical stained glass and pottery where a cobalt compound would be included in a glass melt. In 2019 we were thrilled to relaunch this special blue colour as a permanent part of our range.