Bone Black (Ivory Black): The Charred-Bone Pigment That Painted the Shadows

Open a tube of ivory black oil paint today and you are using a pigment that traces back to the charred bones of animals killed thousands of years ago. The name sounds exotic, even luxurious, suggesting elephant tusks and colonial trade routes. In practice, most "ivory black" sold now is bone black, made from cattle bones heated in sealed containers until the organic matter carbonizes and the calcium phosphate matrix locks the carbon in place. It is one of the few pigments still manufactured using essentially the same process that prehistoric artists used when they burned bones in their fires and ground the residue into paint.

Bone black is a carbon-based black pigment produced by charring animal bones in an oxygen-reduced environment. The resulting material contains roughly 10 percent carbon and 84 percent calcium hydroxyapatite, with smaller amounts of magnesium phosphate and calcium carbonate. Ivory black, historically made from charred ivory, is now virtually identical to bone black in commercial paint, often with a small amount of Prussian blue added to deepen the tone. The pigment produces a stable, dense blue-black that has been used in oil painting, watercolor, and fresco since antiquity.

This entry covers what bone black is, how it differs from other carbon blacks, its history from prehistoric use to the present, which artists relied on it, and how conservators identify it today.

What Is Bone Black and How Does It Work?

Carbon-based black pigments fall into three categories based on their source material: plant blacks (vine black, charcoal), animal blacks (bone black, ivory black), and mineral blacks (carbon black, lampblack). Bone black belongs to the animal category. It is produced by packing animal bones into a sealed crucible or retort and heating them to temperatures between 400 and 800 degrees Celsius. The bones do not burn, because oxygen is excluded. Instead, the organic collagen in the bones decomposes into carbon, which remains trapped within the inorganic calcium phosphate skeleton of the bone structure.

The result is a pigment that is chemically distinct from pure carbon blacks. Bone black contains only about 10 percent carbon by weight, with the remainder being hydroxyapatite, a crystalline calcium phosphate mineral. This mineral content gives bone black a higher density and a different working behavior compared to lampblack or vine black. In oil paint, bone black produces a stiff, pasty consistency that brushes out smoothly and dries to a matte, slightly bluish black. It is less intensely black than carbon black or Mars black, but its slightly granular texture and warm undertone make it useful for underpainting, shadows, and mixing muted tones.

A 2019 multi-analytical study published by researchers at Italy's National Research Council (CNR) characterized commercial bone black pigments from Kremer Pigmente and Zecchi using thermogravimetry, laser-induced breakdown spectroscopy, FTIR, Raman spectroscopy, and X-ray powder diffraction. The study confirmed that in bone blacks, carbonaceous materials are minor components, while hydroxyapatite and calcium carbonate are the main constituents. This composition distinguishes bone black from vine blacks and lampblacks, which are primarily amorphous carbon. Read the study at CNR IRIS.

Origins and History

Bone black is one of the oldest pigments in human use. Charred bone fragments have been identified in prehistoric cave paintings, where early artists used whatever carbonaceous material was available from their fires. The controlled production of bone black, however, required the deliberate charring of bones in sealed containers, a technique that developed alongside metallurgy and pottery firing.

By the classical period, bone black was a recognized pigment. Pliny the Elder mentions black pigments made from burnt bones in his Naturalis Historia. The pigment remained in continuous use through the medieval and Renaissance periods, valued for its stability and availability. Cennino Cennini, in his fifteenth-century treatise Il libro dell'arte, describes the preparation of black pigments from burnt bones, noting that the finest came from ivory.

The distinction between bone black and ivory black is historically real but commercially blurred. True ivory black, made from charred elephant or walrus tusks, was considered superior because ivory has a higher collagen content and produces a finer, denser carbon. A 2025 study published in the International Journal of Conservation Science examined George Stubbs's Portrait of Joseph Banks (c. 1764-1766) using electron microscopy and found that Stubbs used ivory black and burnt sienna in a nine-to-one ratio for his dark brown background. The study identified calcium carbonate bodies derived from heat-denatured ivory, confirming that eighteenth-century painters were using genuine ivory black, not bone black. Read the study at IJCS.

By the nineteenth century, ivory became too expensive for pigment production, and manufacturers switched to bone. The name "ivory black" persisted as a marketing term. Today, most ivory black paint is bone black with additives. The Museum of Fine Arts Boston's CAMEO database notes that current formulations of ivory black usually contain a fine grade of bone black with some Prussian blue. Read more at CAMEO.

Key Artists and Works

George Stubbs (1724-1806)

Stubbs, known for his anatomically precise paintings of horses, used ivory black extensively in his dark backgrounds and shadows. The 2025 analysis of his Portrait of Joseph Banks confirmed that he mixed ivory black with burnt sienna to create the deep brown background, exploiting the pigment's density and warm undertone. Stubbs's skill with materials matched his skill as an anatomist, and his paint handling was unusually precise for the period.

Rembrandt van Rijn (1606-1669)

Rembrandt used bone black in his underpainting and dark passages. Technical analyses of his late works at the Rijksmuseum have identified bone black in the dark backgrounds of paintings like The Jewish Bride (c. 1665) and The Night Watch (1642). Rembrandt exploited the pigment's slightly warm, granular quality to build up dark areas that are not flat black but have depth and atmosphere.

Lo Spagna (c. 1450-1528)

The Italian Renaissance painter Lo Spagna used bone black in his mural paintings at the Church of San Giacomo in Spoleto (1526-1528). A diagnostic campaign at the church used infrared reflection spectroscopy to identify bone black noninvasively, exploiting the sharp absorption band at 2013 cm-1 that distinguishes animal carbon blacks from plant-based blacks. Read the study at PMC.

Da Vinci and Renaissance Underpainting

Leonardo da Vinci and his contemporaries used bone black in the underpainting stages of their works. The dark, muted tones of bone black made it ideal for establishing values before applying color glazes. In The Last Supper (1495-1498), conservation studies have identified bone black in the dark passages of the composition.

How to Identify Bone Black in Paintings

Conservators distinguish bone black from other carbon blacks using several techniques. SEM-EDS (scanning electron microscopy with energy-dispersive X-ray spectroscopy) reveals the presence of calcium and phosphorus, which are unique to bone black among carbon pigments. The higher magnesium content in ivory black compared to bone black can further distinguish the two. XRD identifies the crystalline hydroxyapatite structure. Infrared spectroscopy detects a characteristic sharp band at 2013 cm-1, which appears only in animal carbon blacks and is absent from plant-based and mineral carbon blacks.

Visually, bone black has a slightly warm, brownish-black tone compared to the neutral or cool tone of carbon black and Mars black. In oil paint, it dries to a matte finish and has a granular texture under magnification. If you look at a Rembrandt dark passage under a microscope, the bone black particles are visible as irregular, dense grains embedded in the oil medium.

Related Pigments and Terms

Bone black is part of the broader family of carbon-based black pigments, which includes impasto techniques where thick paint is used for textural effect. It differs from carbon black, which is produced by incomplete combustion of natural gas or oil and is nearly pure amorphous carbon. Vine black, made from charred grape vines or other woody material, has a different composition and working properties. The pigment connects to the broader history of underpainting, where bone black was commonly used to establish dark values. It also relates to chiaroscuro, since the warm, deep blacks of bone black were ideal for creating the dramatic light-dark contrasts of Baroque painting. For broader context, read our post on how to read a painting.

See Bone Black in Person

Bone black is still manufactured and sold by pigment suppliers like Kremer Pigmente and Zecchi, and it appears in paint ranges from Williamsburg, Old Holland, and other traditional paint makers. If you want to see the pigment in historical context, the Rijksmuseum in Amsterdam holds Rembrandt's The Jewish Bride and The Night Watch, where bone black contributes to the deep, luminous darks. The National Gallery in London has works by Stubbs and other eighteenth-century British painters who used ivory black.

The Forbes Pigment Collection at the Harvard Art Museums holds samples of both bone black and ivory black, displayed alongside thousands of other historical pigments. The collection is a working reference for conservation scientists and is periodically open to the public. For more on pigments and painting materials, read our entries on underpainting and chiaroscuro, or explore our guide on how to read a painting to learn more about how pigments create the effects you see in museums.