Single-pigment earths

Earth colors are iron oxides: some dug from the ground (natural ochres, siennas and umbers) and some made in factories (the “Mars” colors). They're the oldest pigments in painting, used since the cave paintings, and still among the cheapest, most permanent and least toxic.

• Ochres (PY43 Yellow Ochre / Raw Sienna (natural), synthetic PY42 Yellow Iron Oxide (Mars Yellow)): dull yellows, the backbone of skin and landscape colors.
• Siennas (PBr7 Natural Iron Oxide (Siennas, Umbers), PR101 Red Iron Oxide (Mars / Burnt Sienna)): raw sienna is a warm, transparent golden brown; burnt sienna is its roasted, redder form.
• Umbers (PBr7 Natural Iron Oxide (Siennas, Umbers)): contain manganese, which makes them dry fast. Raw umber is a cool greenish brown, burnt umber a warmer one.
• Red oxides (PR101 Red Iron Oxide (Mars / Burnt Sienna)): light red, Venetian red and the bluish Indian red.
• Green earth (PG23 Green Earth (Terre Verte)) and Mars black (PBk11 Mars Black (black iron oxide)) round out the family.

One pigment per tube means predictable mixing and clean results. Many tubes named “burnt umber” or “sap green” are mixtures; a single iron oxide behaves the same in every mix, and you can match it across brands by its pigment code.

• Umbers and siennas dry quickly, which makes them ideal for toned grounds, imprimaturas and underpaintings.
• Burnt sienna + ultramarine gives a beautiful range of greys and near-blacks; add white for warm and cool greys.
• Ochre + black or ochre + ultramarine makes soft, natural landscape greens.
• Transparent oxides glaze beautifully; opaque ones cover well and are good for blocking in.
• Umbers contain manganese: keep them out of your mouth, and wear a respirator if you sand them.