Grumbacher Pre-Tested Artists' Oil Color - Terra, 1.25 oz tube

Pigment Information

This color contains the following pigments:

PBk11-Mars Black

PY43-Brown Ochre

PW1-Barium Sulfate

PR102-Natural Light Red Iron Oxide

Pigment Name

PBk11-Mars Black

Pigment Type

earth

Chemical Name

iron oxides

Chemical Formula

FeO or Fe2O3

Properties

Mars Black is an opaque black with a strong and cool masstone, a slightly warm tint, and a warm brown undertone. It is not as black as Ivory Black, but it dries more quickly and has three times the tinting strength. Mars Black is normally the only black available in acrylic form and that is safe to over paint. It can be used in all media without reservation and is widely used as an alternative to Lamp Black and Ivory Black.

Permanence

Mars Black is very lightfast with excellent permanence.

Toxicity

Mars Black has no significant hazards and is the only major black pigment considered non-toxic.

History

The word Mars refers to the Roman god of iron and war. Mars Black was developed in the early 20th century from inorganic, synthetic iron oxide.

Pigment Name

PY43-Brown Ochre

Chemical Name

iron(III)-oxide, partly hydrated

Chemical Formula

Fe2O3(• H2O)

Properties

Brown Ochre provides artists with earthtones from cream to brown and is a dull, dark variety of Yellow Ochre. Its transparency varies widely from opaque shades to more transparent ones, which are valued for their use as glazes. It has good hiding power, produces a quick drying paint, and can be safely mixed with other pigments. The highest quality Brown Ochre comes from Cyprus, where it is yellow in its raw form and is roasted to get the deeper brown-red varieties that result when water is removed. (See Yellow Ochre, PY42/43.)

Permanence

Brown Ochre has excellent permanence.

Toxicity

Brown Ochre is non-toxic.

History

Ochre comes from the Greek word ochros, meaning pale yellow. It has been used since prehistoric times, and evidence of its use has been found in some of the earliest known cave paintings in Lascaux, France. It has also been called Goethite, after the German philosopher and mineralogist Johann Wolfgang von Goethe (1749-1832).

Pigment Name

PW1-Barium Sulfate

Pigment Type

inorganic

Chemical Name

barium sulfate

Chemical Formula

BaSO4

Properties

Barium Sulfate is a low tinting strength neutral white, often used as an extender.

Permanence

Barium Sulfate has excellent lightfastness.

Toxicity

Although barium is a heavy metal and is toxic, barium sulfate has very low solubility in water, and is not easily absorbed biologically. Barium sulfate is used as a contrast medium in radiology.

History

Barium sulfate is the principle component of baryte, a common mineral. It has many industrial uses. John Dalton's discovery (1803) of a process to reduce barium sulfate to barium sulfide was instrumental in the development of the theory of atoms.

Pigment Name

PR102-Natural Light Red Iron Oxide

Pigment Type

inorganic, natural

Chemical Name

iron oxide

Chemical Formula

Fe2O2

Properties

Natural Light Red Iron Oxide is a brick red pigment with a bright, scarlet top tone. Mineral sources vary considerably in both hue and transparency. It is generally opaque and has great tinting strength and hiding power, but more transparent versions are available. It creates salmon pinks when mixed with white. Natural Light Red Iron Oxide is often replaced by Mars colors or bright red oxides, which are cleaner and more powerful.

Permanence

Natural Light Red Iron Oxide has excellent permanence and lightfastness.

Toxicity

Natural Light Red Iron Oxide has no significant hazards.

History

Natural red iron oxide comes from the mineral ore hematite, called bloodstone by the ancient Greeks from the word hema, meaning blood. It is one of the oldest pigments, has been used by every major civilization, and was an important mineral for medieval alchemists. It was not widely used in artists' materials until the 17th century and was not produced in large quantities until the 18th century.