title: Cobalt blue
context: Cobalt blue in impure forms had long been used in Chinese porcelain,[1] but it was independently discovered as a pure alumina-based pigment by Louis Jacques Thénard in 1802.[2] Commercial production began in France in 1807. The first recorded use of cobalt blue as a color name in English was in 1777.[3] 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.
question: When was cobalt first used for blue paint?
answers: 1777