Red lead
A bright orange-red made by roasting lead white, cheap enough to use by the pot, and the pigment that gave the word "miniature" to Western art — a miniature was originally simply a small painting done in minium.
Origin
Heat lead white in air to around 480 °C and it converts through a yellow intermediate, litharge, to red lead tetroxide. The process was known to the Greeks — Pliny describes it, attributing the discovery to an accidental fire in a warehouse at Piraeus — and it is one of the oldest deliberate pigment syntheses. Because it starts from lead white, which was made in enormous quantity anyway, red lead was cheap and universally available, in sharp contrast to vermilion. Its Latin name, minium, was applied loosely and sometimes confusingly to both this pigment and cinnabar, which is why the two are conflated in some old sources.
In art history
Red lead is the red of manuscript illumination above all. The rubrics of medieval books — the headings and initials written in red, from which the word "rubric" comes — are red lead, and the illuminators who painted them were the miniatores. In panel painting it appears in five eras here, generally as an underlayer or in mixtures rather than as a final surface, since vermilion was better and painters used minium where the difference would not show. It is also the standard orange of Persian and Indian miniature painting, and it was for centuries the primary anti-corrosive paint for structural steel — the red-orange of unweathered bridges, cranes and ships was red lead primer, applied in millions of tonnes until it was legislated out in the late twentieth century.
In the studio
It is opaque, warm, and dries very fast in oil, faster than almost anything. Its failings are chemical and well documented. In the presence of light and moisture it can convert to lead dioxide or to white lead carbonate, so red lead passages in manuscripts sometimes appear brown-black or chalk-white — the darkened rubrics of many medieval books are this reaction, not fading ink. It blackens on contact with sulphur pigments. It is also poorly compatible with organic acids in some binders. And it is severely toxic, being a highly bioavailable lead compound.
Afterlife
Removed from artists' ranges and from industrial paint by lead legislation. Cadmium orange and the azo oranges cover the same ground with none of the risks. Red lead remains in use in a few specialised industrial contexts, in conservation, and in traditional manuscript and icon painting where historical accuracy is the objective.
Where it appears
Every era and artist in this atlas whose palette includes this pigment.