Cobalt blue
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.
Biofouling
With the rise of iron hulls in the 19th century, copper sheathing could no longer be used due to its galvanic corrosive interaction with iron. Anti-fouling paints were tried, and in 1860, the first practical paint to gain widespread use was introduced in Liverpool and was referred to as "McIness" hot plastic paint. These treatments had a short service life, were expensive, and relatively ineffective by modern standards.