Cobalt blue is the cool blue color of the pigments made using cobalt salts of alumina. Cobalt blue pigments are extremely stable, and have historically been used as colouring agents in ceramics, (especially Chinese porcelain), jewellery, and paint. Transparent glasses are tinted with the silica-based cobalt pigment smalt.
Chemically, cobalt blue pigment is a cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. The compound is made by sintering finely ground CoO and Al2O3 (alumina) at 1200 °C. Cobalt blue is lighter and less intense than (iron-cyanide based) Prussian blue.
Read more about Cobalt Blue: Historical Uses and Production, Cobalt Blue in Human Culture, Toxicity
Famous quotes containing the word blue:
“How prone poor Humanity is to dam up the minutest remnants of its freedom, and build an artificial roof to prevent it looking up to the clear blue sky.”
—E.T.A.W. (Ernst Theodor Amadeus Wilhelm)