Madder and the red lakes
The transparent reds: not ground minerals but dyes, precipitated out of solution onto a colourless powder and used as glazes. Red lakes gave European painting its crimsons, and most of them are quietly fading.
Origin
A lake is made by dyeing a substrate — usually alum, sometimes chalk or a clay — and drying the result into a pigment. The dyes came from three main sources. Madder is the root of Rubia tinctorum, cultivated across the Mediterranean and the Near East since antiquity, giving a cool rose to deep crimson. Kermes comes from the dried bodies of scale insects living on Mediterranean oaks, and was the luxury red of the ancient and medieval world. Cochineal, from a related insect farmed on cactus in Mexico, arrived in Europe after the Spanish conquest and was so much stronger than kermes that it displaced it almost entirely — it became one of the most valuable exports of the Americas after silver, and Spain guarded the source as a state secret for two centuries while European naturalists argued about whether it was a seed or an animal.
In art history
Red lakes appear in seven eras here under the name crimson lake, and their function is consistent: they are the glaze over an opaque red. A Venetian mantle is vermilion or red ochre for body with a lake glazed over it for depth, and the two-layer structure is what makes the colour feel like velvet rather than paint. Titian, Rubens and Rembrandt all worked this way. Lakes also gave the only true purples and pinks available before the nineteenth century, mixed with blue or extended with white. Their role in textiles was even larger — the crimson of a cardinal's robe, of a Turkey carpet, of a British army coat, was madder or cochineal on wool.
In the studio
The defining property is transparency, and the defining problem is impermanence. Organic dyes fade under light, and lakes fade faster in thin glazes than in thick ones — precisely the way they were used. A great deal of European painting has lost its lake glazes altogether: the pale, oddly bald reds and the pinkish flesh in many old pictures are what remains once the top layer has gone, and a Rubens whose crimsons have faded reads as a different painting. Cochineal is the most fugitive, madder the most durable, and the alizarin component of madder is more stable than its purpurin component, so faded madder shifts hue as well as losing strength.
Afterlife
In 1868 Carl Graebe and Carl Liebermann synthesised alizarin, the principal colouring compound of madder — the first natural dye ever synthesised — and the madder-growing industry of France and the Netherlands collapsed within a decade. Synthetic alizarin crimson became the standard transparent red and remains familiar, though it too is only moderately lightfast; modern practice increasingly replaces it with quinacridone, which matches the transparency and is genuinely permanent. Cochineal survives as a food colouring, listed as carmine or E120.
Where it appears
Every era and artist in this atlas whose palette includes this pigment.