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Natural Red Oxide (Indian Red) [500 g bag] (17.6 oz.)
Item No: 450:510500
Category: 29
Price:
$17.20
Iconofile Sale Price: $13.85
You Save: $3.35
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Quantity:
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Description:
500 g (17.6 oz)
Our French natural red oxide is from the last remaining European company operating the ochre deposits in the French quarries of Gargas and Rustrel nestled in a 12 mile long enclave in the heart of the Luberon Mastiff, the ochre country. Red iron oxide or ferric oxide is the principle coloring agent in red ochre, such as Indian Red, Terra Pozzuoli, Venetian Red, etc. These pigments are basically hematite associated with varying proportions of mineral impurities such as clay, chalk and silica. They differ from yellow ochre and brown ochre in that they do not contain water. In other words, the iron to which they owe their color is iron oxide not hydrated iron oxide.
Natural red oxides, such as hematite and Indian red, are very opaque, absolutely permanent and have excellent covering power. They are strong absorbers of ultraviolet light. The best bluish shades are called Indian red; the yellowish shades, light red, English red, and Venetian red. Formerly there was much confusion in the nomenclature of the red oxides; the terms given in this list are those specified in the ASTM Standard.
| Common Names: |
English: red oxide
French: oxyde rouge
German: Oxid rot
Italian: rosso ossido
Portuguese: vermelho óxido
Spanish: rojo óxido |
| Alternate Names: |
English: English red, Indian red, light red, red iron oxide, Venetian red
French: rouge Indien
Spanish: rojo Indio
Mars red is the name given to the artificial substitute of natural red iron oxide. |
Origin and History
Natural red iron oxide is based on the mineral ore hematite.
The word hematite comes from the Greek word hema, meaning blood and was given the name "bloodstone" in ancient Greece (Theofrastus, c. 325 B.C.), implying that the mineral is blood red in color. Hematite is an important ore of iron and its blood red color in the powdered form lends itself well as a pigment. Hematite is among the oldest pigments known to humankind and has been used by every major civilization.
Source
In nature hematite rarely occurs as crystals but usually as nodules or earthen masses. The color of the crystalline form varies from steel-gray to black, while crypto-crystalline hematite is dull red to bright red. This common mineral is found in deposits of the most diverse types. There are several varieties of hematite, two of which are suitable for use as pigments: oolitic hematite, which is a friable earth composed of small rounded grains of dark red color that are lustrous and greasy to the touch; and hematite rose, a fine-crystalline and crypto-crystalline form of hematite of red color, which are usually encountered in friable earthen masses or reniform aggregates of bladed crystals in a circular arrangement giving the appearance of a rose. Red iron oxides (hematite) are found around the world and have been used as pigments since prehistory.
Permanence and Compatibility
Pigments made from the mineral hematite are dependable in mixtures with all other permanent pigments, and are considered to be permanent with considerable tinting strength and opacity. They do not react with solvents, and are indifferent to alkalis, but are partially soluble in acids. Zinc white and hematite yield excellent flesh tints. Mixtures of Alizarin Madder and hematite were offered as Tuscan Red or Pompeian Red, according to F. W. Weber. The Alizarin Madder in this mixture does not decompose as is likely when mixed with hydrated iron oxide pigments such as ochre, sienna and umber.
Oil Absorption and Grinding
Natural red iron oxide absorbs a moderately high amount of oil. The oil absorption ratio is 6–21 parts by weight of pigment to 100 parts by weight of linseed oil. If the measurement were grams, umber would require 100 grams (by weight) of linseed oil to grind 6 to 21 grams (by weight) of pigment to form a stiff paste. It forms an average drying oil paint, and a hard, fairly flexible film.
Toxicity
Natural red iron oxide is not considered to be toxic, but care should be used in handling the dry powder pigment to avoid inhaling the dust.
Pigment: Natural Red Oxide (Indian Red)
| Color: |
Red |
| Colour Index: |
Pigment Red 102 (77491) |
| Chemical Name: |
Iron Oxide |
| Chemical Formula: |
Fe2O3 |
| ASTM Lightfastness Rating |
| Acrylic: |
I |
| Oil: |
I |
| Watercolor: |
I |
| Properties |
| Density: |
5.27 |
| Hardness: |
5.0–6.0 |
| Refractive Index: |
2.78–3.01 |
 Read cautions about handling pigments
Availability: Usually ships within 24 hours.
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