Before the paint tube existed, obtaining a specific color could cost fortunes, years of travel, or a life. The history of art is also the history of how humans pursued color with an obsession that's hard to imagine today.
Ultramarine blue — that deep blue that appears in the Virgin's robes in almost all medieval and Renaissance painting — was made from lapis lazuli, a semiprecious stone that existed in only one mine in the world: in the mountains of Badakhshan, in what is now Afghanistan. It had to be mined, transported across Central Asia and Europe, and ground for weeks. It was more expensive than gold by weight. Commission contracts of the era specified exactly how many grams of ultramarine the artist could use and in which parts of the work.
Emerald green, popular in 19th-century painting, was a combination of arsenic and copper that produced an unprecedented bright green. It was also highly toxic. Rooms papered with wallpaper of that color — made with the same pigment — are believed to have contributed to Napoleon's poor health during his exile on Saint Helena. Some historians suspect the arsenic in his wallpaper was a factor in his death.
Lead white was the standard white of European painting from antiquity to the 20th century. It was bright, opaque and dried well. It was also slowly lethal. Prolonged lead exposure causes cumulative neurological damage. Goya, who used large amounts in his technique, developed progressive deafness and a mental state that some historians partly attribute to chronic poisoning. His "Black Paintings" — the murals he covered the walls of his own house with — were made with lead.
Naples yellow, used since the Renaissance, was made with lead antimonate: also toxic, also bright, also hard to replace. The indigo pigment — the darkest blue of Asian and European painting — depended on a tropical plant grown mostly with slave labor in the colonies. The art trade and the trade in people were connected by color.
The first synthetic color of modern history was Prussian blue, discovered by accident in Berlin around 1704. A paint maker was trying to make red and got blue. It changed the color market forever: for the first time, a specific shade could be produced consistently, cheaply and in quantity. Impressionism — with its obsession with capturing light — would not have existed without the 19th-century synthetic pigment revolution.
Today, oil tubes in any art store contain colors that in the Renaissance would have cost the equivalent of months of work. Artificial ultramarine blue, first synthesized in 1828, is indistinguishable to the eye from the original and costs cents. What Renaissance artists negotiated by the gram is now bought by the kilo. But something was lost in that democratization: the weight of knowing that blue came from a specific place in the world, carried by specific hands, valuable for its absolute rarity.