A natural black earth that is a dense, opaque, heavy color that is absolutely permanent. It is comparatively neutral in undertone, wets easily, and is non-greasy, when compared to carbon blacks. It is a useful pigment when these qualities are required.
Rublev Colours Aqueous Dispersions are pigments dispersed in water ready to be mixed with water-based mediums. These dispersions are especially made for use with traditional painting mediums, such as egg tempera, casein tempera, fresco, watercolors and distemper (glue tempera). They are also ideally suited for use with gesso to make toned grounds for drawing and painting. Pigment dispersions from Rublev Colours contain only naturally-derived ingredients, in addition to pigment and water, making them ideally suited for traditional mediums. Unlike other pigment dispersions that are typically made for acrylic medium, Rublev Colours Aqueous Dispersions do not contain coalescent solvents, artificial dispersing resins and other additives that interfere with natural mediums. Aqueous Dispersions make preparing traditional mediums easy; you do not have to hassle with powders, grinding pigments in medium and calculating binder ratios to make water-based paint. They make adding the right amount of paint binder, such as egg yolk, a no brainer because the right amount of water is already contained in the dispersion, simply add egg yolk.
|Pigment Names |
|Common Names: || English: black oxide |
French: oxyde noir
German: Oxid Schwarzes
Italian: ossido nero
Portuguese: óxido preto
Spanish: óxido negro
|Alternate Names: || English: black iron oxide, iron oxide |
French: fer oxydé, naturelle noir Indien
Mars black is the name given to the artificial substitute of natural black oxide.
Origin and History
Black oxide is a recent development in modern pigments and was not often encountered in artists' palettes before the 19th century.
The source of natural black oxide usually is from an iron ore called magnetite. Magnetite, also known as lodestone, is a ferrous ferric oxide (ferrosic oxide) that is a heavy, black color and opaque. Theoretically, black iron oxide contains slightly more iron metal than red oxide but not nearly as much as yellow oxide. The native mineral may contain varying amounts of manganese, sulfur, clay and silica.
Permanence and Compatibility
Natural black oxide is absolutely permanent colors for all uses on the artist's palette. It is compatible with all other pigments, and can be used with good results in all mediums.
Oil Absorption and Grinding
Natural black oxide absorbs a moderately low amount of oil. The oil absorption ratio is 10–15 parts by weight of pigment to 100 parts by weight of linseed oil. If the measurement were grams, it would require 100 grams (by weight) of linseed oil to grind 10 to 15 grams (by weight) of pigment to form a stiff paste. It makes an average drying oil paint, and forms a hard, fairly flexible film.
Natural black oxide is not considered toxic, but care should be used in handling the dry powder pigment to avoid inhaling the dust. Rublev Colours Pigment: Roman Black
|Pigment Information |
|Color: ||Black |
|Colour Index: ||Pigment Black 11 (77499) |
|Chemical Name: ||Iron oxide produced from magnetite ore |
|Chemical Formula: ||Fe3O4 |
|ASTM Lightfastness Rating |
|Watercolor: ||I |
|Density: ||5.15 |
|Hardness: ||5.5–6.0 |
|Refractive Index: ||n=2.42 |