The first orange pigments were not red mixed with yellow, but naturally occuring ochres, muddied by impurities. The first vivid orange pigment was harvested from the mineral realgar in antiquity, but like many pigments, it’s dangerous. “Known as ‘the ruby of arsenic,’ realgar is extremely toxic,” paint-maker David Coles writes in his forthcoming book Chromotopia: An Illustrated History of Color. “The red crystals of the mineral yield a rich orange pigment, but it is made of arsenic disulphide.” Realgar was found in geothermal fissures, along with its yellow sister-mineral, orpiment. (Interestingly enough, Coles notes, in China, though both were called yellow, the former was “masculine” while the latter was “feminine.”) But it wasn’t a hit with artists or craftsmen due to its instability as a color; it did, however, gain popularity as a means for pest control in the Middle Ages.
Minium, or “red lead,” was a more useful orange pigment. One of the first synthetic hues to ever be produced, it was created by the Roman Empire. Cheap and easy to make, red lead could come in shades of ruby or orange, and was used prolifically for centuries. It was especially favored for medieval paintings: Painters who specialized in its use were known as miniators; their craft, painting at a very small scale, often for illuminated manuscripts, was named “miniaturas,” the basis of the word we use to identify tiny things today.
Red lead gave way to vermilion in the Middle Ages, and the deep red of vermilion enjoyed a long history of use in Europe, India, and China. In the mid-18th century, technology had advanced far enough that all iron-oxide pigments (reds, oranges, and yellows) could be mass-produced. But it wasn’t until the introduction of cadmium yellow in 1840, followed by cadmium red in 1910, that the full range of orange hues was unleashed to the world. Cadmium pigments are much more chemically stable than their predecessors.