Smalt was an important blue pigment used in European oil paintings in the 15th through the 18 centuries. Its origins probably lie in the blue pigment used by the ancient Egyptians, known as us as ‘Egyptian blue’ discussed earlier in part 2 of our pigment series; both pigments are made from glass that has been colored blue and both are also used as glazes on ceramics. However, Egyptian blue contains copper, whereas smalt derives its color from cobalt.

Being a glass, smalt is transparent and the color is never strong, although this varies depending on how much cobalt is present. The pigment is comprised of large particles and is quite coarse. If ground too fine the color is weakened. It provided a much cheaper alternative to ultramarine and its manufacture became a specialty of the Dutch and Flemish in the 17th century. Smalt is a very good dryer and was used for this purpose as well as to give bulk to thick glazes containing lake pigments which are poor dryers.

Renaissance artists used ground cobalt containing glass, smalt, to add vibrancy to their paintings. A portrait of Sir William Butts by Hans Holbein the Younger (1497-1543), is among the earliest paintings in which smalt has been found as a pigment. Stay tuned for our next video when we discuss the use and history of Prussian Blue.