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.
Lead-tin-yellow
The origin of lead-tin-yellow can be dated back to at least the thirteenth century when Type II was applied in frescos, perhaps having been discovered as a by-product of crystal glass production. Until the eighteenth century Type I was the standard yellow used in oil painting. It was then almost completely replaced in use by Naples yellow. After 1750, no paintings seem to have been made containing the pigment. In the nineteenth century its existence had been forgotten and its application was only in 1941 rediscovered by the German scientist Richard Jakobi, the director of the Doerner Institute. That it faded from collective memory has been explained by a confusion with massicot, the name of which was also applied to lead-tin-yellow. The term "lead-tin-yellow", a literal translation of German "Blei-Zinn-Gelb", is therefore a modern designation, not the historical name of the pigment. In English it used to be called "general" after the Italian "giallorino". After 1967, Hermann Kühn in a series of studies proved its general use in the traditional oil technique of earlier centuries, coining the distinction between the Type I and Type II varieties.