Manganese Oxide

Manganese dioxide (MnO2) is one of the oldest colorants used by humans, appearing in cave paintings over 30,000 years old. In ceramics, manganese produces a range of warm earth tones from honey browns to deep purples to metallic blacks.

In small amounts (1 to 3 percent), manganese adds warmth and depth to clear or celadon glazes, producing honey and amber tones similar to iron but with a slight purple cast. At 4 to 6 percent, it produces rich brown-purples, especially in alkaline glazes. At 8 percent or more, manganese saturates and can produce metallic or bronze surfaces.

Granular manganese (coarser particles) is often sprinkled into clay bodies or glazes to produce speckled surfaces, where each granule melts into a small dark spot during firing. This is a popular technique for Shino and ash glaze bodies.

Manganese is particularly beautiful when combined with other colorants. Small amounts with cobalt produce rich plum purples. With iron, it deepens tenmoku browns. With copper, it can produce slate greys and blacks.

Safety note: Manganese dust is a serious respiratory hazard with cumulative neurological effects. Always wear a proper respirator (not just a dust mask) when weighing out manganese oxide.

Typical usage: 1 to 4 percent for warm browns, 4 to 8 percent for purple-browns, 8 percent+ for saturated metallic effects.