Cobalt zinc aluminate produces a deep, bright shade of Cobalt Blue
Permanence
Cobalt salts are extremely lightfast and temperature stable.
Toxicity
Cobalt salts are toxic.
History
Since the discovery of processes for mining and purefying Cobalt Blue (PB28) in the 19th century, additional processes for manufacturing and purifying other cobalt salts have become available. Their use as artist pigments has followed.