Rublev Colours Blue Ridge Hematite is a natural red iron oxide from the heart of the Blue Ridge Mountains of Virginia. The high iron content (over 80%) makes it an intense tinting pigment. Natural red iron oxides are opaque, permanent, and have excellent covering power. They are strong absorbers of ultraviolet light. The best bluish shades are Indian red; the yellowish shades are light red, English red, and Venetian red. Formerly there was much confusion in the terminology of red iron oxides; the terms 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
Natural red iron oxide is based on the mineral ore hematite. The word hematite comes from the Greek word hema, meaning blood, and was named "bloodstone" in ancient Greece (Theofrastus, c. 325 B.C.), implying that the mineral is blood red in color. Hematite is an important iron ore; 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.
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 is 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 () are found worldwide 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 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 (in oil paints, you may want to substitute zinc white with another transparent white pigment). Mixtures of alizarin or madder lake and hematite were offered as Tuscan red or Pompeian red, according to F. W. Weber. Alizarin or madder lake in this mixture does not fade as readily when mixed with iron oxide hydroxide pigments such as ocher and sienna.
Oil Absorption and Grinding
Hematite absorbs a moderate amount of oil. The oil absorption ratio is 20 parts by the weight of linseed oil to 100 parts by the weight of pigment. If the measurement were grams, hematite would require 20 grams of linseed oil to grind 100 grams of pigment to form a stiff paste. It forms an average drying oil paint and a strong, flexible film.
Hematite is not considered toxic, but care should be used in handling the dry powder pigment to avoid inhaling the dust.
Pigment: Blue Ridge Hematite
|Colour Index:||Pigment Red 102 (77491)|
|Chemical Name:||Iron Oxide|
|ASTM Lightfastness Rating|
|Oil Absorption:||20 g / 100 g|