Cobalt blue

Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with alumina at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt blue is lighter and less intense than the (iron-cyanide based) pigment Prussian blue. It is extremely stable and has historically been used as a coloring agent in ceramics (especially Chinese porcelain), jewelry, and paint. Transparent glasses are tinted with the silica-based cobalt pigment smalt.An example of cobalt blue hue (not pure cobalt blue).Pierre-Auguste Renoir, Boating on the Seine (La Yole), c. 1879 Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with alumina at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt blue is lighter and less intense than the (iron-cyanide based) pigment Prussian blue. It is extremely stable and has historically been used as a coloring agent in ceramics (especially Chinese porcelain), jewelry, and paint. Transparent glasses are tinted with the silica-based cobalt pigment smalt. Cobalt blue in impure forms had long been used in Chinese porcelain, but it was independently discovered as a pure alumina-based pigment by Louis Jacques Thénard in 1802. Commercial production began in France in 1807. The first recorded use of cobalt blue as a color name in English was in 1777. The leading world manufacturer of cobalt blue in the 19th century was Benjamin Wegner's Norwegian company Blaafarveværket ('blue colour works' in Dano-Norwegian). Germany was also famous for production, especially the blue colour works (Blaufarbenwerke) in the Ore Mountains of Saxony. Art Automobiles Construction Sports Vexillology Video games Cobalt blue is toxic when inhaled or ingested. Potters who fail to take adequate precautions when using cobalt blue may succumb to cobalt poisoning.