Caput mortuum

Caput mortuum is a natural iron oxide pigment powder: natural red iron oxides heat-treated to a dark violet-brown (PR102). It is opaque and lightfast and gives deep purple-browns for shadows, draperies and dark flesh tones in oil, egg tempera, watercolor, gouache, acrylic and fresco.

Key facts

• Color: dark violet-brown
• Pigment type: Natural mineral pigment (heat-treated iron oxide)
• Colour Index: PR102 (C.I. 77491)
• Composition: iron(III) oxide, Fe₂O₃, from calcined natural iron oxides
• Also known as: cardinal purple
• Opacity: opaque
• Lightfastness: 8 of 8 on the Blue Wool Scale (supplier data)
• Chemical resistance: alkali 4/5, lime 4/5 (supplier data, 5 = best); stable in weak acids, dissolved by strong mineral acids
• Suitable for: oil, acrylic, egg tempera, watercolor, gouache, fresco (lime), ceramics
• Packaging: 50 g jar · 1 kg bag

How to use

Mix the powder into linseed oil, egg yolk, gum arabic or acrylic medium with a palette knife or muller. It covers well and darkens mixtures quickly, so add it in small amounts; with white it gives muted mauves. Its lime resistance is rated 4 of 5, slightly below most iron oxides, so test it on a sample before painting a fresco into fresh lime plaster.

About caput mortuum

Caput mortuum is Latin for dead head: alchemists used the term for the worthless residue of a chemical operation. As a pigment it was first a by-product of sulfuric acid manufacture in the 17th and 18th centuries, and its deep purple was popular for the robes of religious figures in the 18th and 19th centuries. Many modern caput mortuum pigments are synthetic; ours is made from natural iron oxides.

Safety

Natural iron oxide minerals can contain crystalline silica (quartz): avoid breathing the dust. Handle dry pigment with care: avoid breathing the dust and contact with eyes. Wear a dust mask (FFP2/N95) and gloves when working with the powder, work in a well-ventilated area and wipe up spills with a damp cloth. Do not eat, drink or smoke while working; wash your hands afterwards. Keep away from children and pets. For artistic and technical use only — not for cosmetics, food or tattoos.

FAQ

Is caput mortuum made from mummies?

No. It is iron oxide. The name was sometimes also applied to mummy brown, a historic brown made from mummies that went out of production in the 20th century.

How does it differ from Caput Mortuum Violet?

Our Caput mortuum is made from natural iron oxides (PR102) and is browner. Caput Mortuum Violet is a synthetic iron oxide (PR101) with a more violet tone.

Is it lightfast?

Yes. The supplier rates it 8 of 8 on the Blue Wool Scale, and the color is stable to light and heat.