When was cobalt first used for blue paint?
Cobalt blue
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.
Cobalt
Several cobalt compounds are oxidation catalysts. Cobalt acetate is used to convert xylene to terephthalic acid, the precursor of the bulk polymer polyethylene terephthalate. Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes, and inks as "drying agents" through the oxidation of drying oils. The same carboxylates are used to improve the adhesion between steel and rubber in steel-belted radial tires. In addition they are used as accelerators in polyester resin systems.