Smalt, standard grind, PB 32

As the oldest man-made cobalt blue pigment, Smalt derives its name from the Italian smaltare, meaning "to melt." It is a potash silicate glass, deeply colored with cobalt oxide, then quenched and ground into a fine powder. While its exact origins are obscure, cobalt has been identified in ancient Egyptian glass, though there is no evidence it was used as a painter's pigment in antiquity.

The European history of smalt began in earnest around the mid-15th century following the discovery of cobalt minerals near the Bohemia-Saxony border. It became a staple of German Renaissance and Baroque painting, prized especially for depicting the sky in frescoes. By the early 20th century, the rise of stable industrial blues nearly erased the knowledge of smalt from history. This changed in 1977, when Georg Kremer successfully recreated the pigment, leading to the founding of Kremer Pigmente. Today, Kremer Pigmente remains the world’s sole manufacturer of smalt, producing it according to a traditional 1820 recipe.

• Chemical description: Cobalt potassium silicate glass. Pigment Blue 32, C.I. 77365
• Resistance to alkali: 5 (1 is bad, 5 is best)
• Resistance to lime: 5 (1 is bad, 5 is best)
• Resistance to acid: 3 (1 is bad, 5 is best)
• Chemical Formula: Glas
• Lightfastness - thinned: 8 (1 is bad, 8 is best)
• Lightfastness - medium: 8 (1 is bad, 8 is best)
• Lightfastness - concentrated: 8 (1 is bad, 8 is best)
• ColorIndex: PB 32.77365
• Opacity: transparent
• Suitability: Acrylics, Ceramic, Lime / Fresco, Tempera