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Earth Pigments: The Artist

Discover the History and Prominence of Artist's Oldest Paintbox: Natural Earth Pigments

Fourth generation miners pick at an open vertical mine, exposing a layer of crude sienna. It is an awesome sight. They stand on ladders, carefully secured into the earth, and as they work, bright chunks of sienna roll down the slope and rest at my feet. I pick one up for inspection. Its color and feel make me want to draw with it, right now, like a huge, chunky pastel. Nearby, at a second mine, automated shovels scoop up the pigment treasures while miners direct movement and selection. In Hiwassee, Virginia, along the Blue Ridge Range of the Appalachian Mountains, pigments still come right out of the earth in bright, vivid chunks. These are the same pigments that were used by our Paleolithic ancestors for their cave paintings at Lascaux, France over 16,000 years ago.


History of Use
Thousands of years before the first recorded paintings, cave dwellers used colors dug up from the earth to adorn their bodies, clothing and implements and to enhance their living quarters. These practices were closely tied to the cultural and religious rituals that were an integral part of the cave dweller's daily life. Graves unearthed by archaeologists exposed bodies covered in red pigment or chunks of pigment buried alongside bodies. Red, associated with blood, the most life-sustaining of a bodily fluids. was the appropriate color to symbolize life's meaning and end. The word hematite (the source of many iron oxide pigments) is derived from the Greek word, hema meaning blood.

Prehistoric dwellers may have discovered that unlike the dye colors derived from animal and vegetable sources. the color that came from iron oxide deposits in the earth was not transitory and would not fade with the changing environment. For this reason, it is estimated that men traveled long and far to maintain a steady supply of red pigment. In every locality where prehistoric sites were discovered, from Texas to South Africa, trails lead to near and far hematite deposits where man mined. It has even been deduced that the impetus behind all mining activities was sparked by prehistoric man's need for red pigment.

Page One of most art history surveys begin with the Paleolithic cave paintings at Lascaux, France dating back to about 15,000 B.C. The caves were discovered in 1940, quite accidently, when two young men searching for a dog found the opening. Until 1963, when the caves were officially close hundreds of thousands of historians and tourists witnessed the wonder of man's first recorded, paint expression. The sight of the elegant "Chinese horse" and the walls of fighting bulls kept a steady stream of visitors into the caves.

The reason for the cave closure was due to a dual malady called the "green and white sickness." a strange type of pigment-deteriorating fungus that formed on the cave paintings. Conservators attributed the malady to the warmed atmosphere in the cave-the direct result of gases exhaled by the continual throng of visitors, compounded by the constant flashes from eager cameras.

Combining their expertise, art historians and conservators used examination, chemical analysis and ethnographical (cross-cultural) comparison to hypothetically reconstruct the artistic materials and techniques of the cave dweller. It is assumed that all the colors used by Paleolithic artists have a foundation of mineral oxide (either iron or manganese) or carbon. Their limited palette was produced from three basic colors: red, black and yellow. Reds, yellows, and browns came from the limonites and hematites (ochres and siennas), where a range from reddish brown to straw color is evident in the paintings. Shades of red-violet and mauve were perhaps the product of natural peroxide of iron transformed slowly and naturally into violet oxide. [2] Blacks were derived from manganese ores and charcoal.

Excavations in the Lascaux area prompted speculation that cave dwellers traveled as far as 25 miles to obtain ion oxide pigments The oxides of iron dug right out of the ground in the form of lumps were presumably rich in clay. This consistency was conducive to the formation of crayon sticks and also could be made into a liquid paste more closely resembling paint. It is believed the lumps were ground into a fine powder on the cave's natural stone hollows where stains were observed. Shoulder and other bones of large animals, stained with color, were discovered in the caves and presumed to be used as mortars for pigment grinding. The pigment was made into a paste with various binders, including water, vegetable juices, urine, animal fat, bone marrow, blood and albumen.

Historians hypothesize that paint was applied by brushing, smearing, dabbing and spraying techniques. Large areas were covered with fingertips or pads of lichen or moss. Twigs produced drawn or linear marks, while feathers blended areas of color. Brushes made from horse hair were used for paint application and outlining. Paint spraying, accomplished by blowing paint through hollow bones, yielded a finely grained distribution of pigment, like airbrush.

Iron oxide pigments constituted the basic palette of ancient artisans, from Egypt to India and China. The Minoans, attributed with inventing the fresco, mixed their pigments with water and applied them to a fresh lime surface. The technique, called buon fresco, requires pigments that bond permanently to lime. Iron oxide pigments, unaffected by alkalies, remain the basic palette of fresco painters, from the Minoans to the present.

Throughout the Middle Ages and the Renaissance, mineral pigments (including those from iron oxide) continued to be used by painters. Available since antiquity, medieval Italian painters used terra verte for underpainting middle and shadow flesh tones. Its commonly used synonym, Verona Green, comes from terra verte's prevalence in the area around Verona, Italy. Those deposits were exhausted in the late 1930s. Small amounts also came from Cyprus. Terra verte is rarely found today, however, and viridian or chromium oxide yield similar color ranges.

Like the Paleolithic cave dwellers, late medieval and Renaissance artists used natural chalks made from mineral pigments. Dug right out of the earth and shaped into sticks with knives, these chalks were ready for drawing. Natural red chalks, with their rich, warm color, were popular from about 1500 to 1900. Such artists as Michelangelo, Rembrandt and Antoine Watteau used this medium to produce some of the most coveted drawings in the world today.

To have the right consistency as a drawing chalk, iron oxide pigment had to be diffused with enough clay to give it softness and texture. Many hematites have outstanding color but are too hard and brittle to produce quality lines. The best earth for natural red chalk is mineralogically described as "red ochre variety of hematite." In the massive iron ore deposits of Michigan's Upper Peninsula, one can find the perfect blending of substances to make an excellent red drawing chalk.

By the 18th century, synthetic red iron oxide pigments were being made in a laboratory setting. Called Mars Red, these pigments were found to have all the properties, including durability and permanence, of their natural counterparts. By the middle of the 19th century, regular manufacture of synthetic red iron oxide pigments began and has continued to be improved and simplified up to the present. Synthetic yellow iron oxide pigments (Mars Yellow) have been made since the early 1920s, with major improvements occurring in the 60s and continuing to the present. The development of synthetic brown iron oxide pigments has evolved through modification of the technology used in producing reds and yellows. Today, synthetic iron oxide pigments are used extensively by the paint, plastics and other industries. Often these manufacturers use blends of natural and synthetic iron oxides to produce the best results. The economy of the natural pigments with the higher level of quality control found in the synthetic ones yield an optimal product.


Defining Natural Iron Oxide Pigments
Iron oxides, or earth pigments, as they often are called, are an important group of inorganic pigments derived from minerals. Iron oxide pigments are yellow, red, brown and green, but artists know them as ochre, sienna, red oxide, umber and terra verte. Unlike pigments made in a laboratory, the color of natural iron oxide pig ments varies with the composition of the particular segment of earth from which they come. The color of these pigments is derived from three constituents: the principal color producing ingredient, secondary color ingredients and a color base. The combination of these ingredients produces the particular color of the earth. The innumerable forms and variations in which these ingredients can combine result in the wide range of possible yellows, reds, browns and greens.

Principal color producing ingredient: Iron oxide is the principal color producing ingredient in the earth. The properties of the particular iron oxide present in the earth determines its color. The nature of the iron oxide found in the deposit, rather than its percentage, is critical to the resulting earth color. Most rock contains some iron oxide. Those bearing the least amounts are limestones. white clays and colorless kaolins. Those containing the highest amounts are the rocks from which metallic iron is extracted.

Secondary coloring ingredients: Calcium, manganese oxide, carbonic materials, silica and limestone are some common modifiers that affect the specific color of natural iron oxides. Manganese oxide, for example, enriches the brown in umbers.

Color base: Nearly all iron oxides have a clay base. Clay is the weathered product of silicate rocks and is extremely varied in composition. As a result, it has numerous effects on the earth's color.


Pigment Sources
The natural iron oxide pigments available today are derived from four types of iron ore: hematite, limonite, siderite and magnetite. Most come from hematite and limonite ores.

Hematite is anhydrous (without water) ferrous oxide and yields pigments reddish in color. Limonite is hydrous (contains water) ferric oxide. It yields pigments that range from light yellow to dark brown in color. Ochres, siennas and umbers are from limonite ores. Ochre is clay permeated with hydrous iron oxide. The amount of iron present determines whether the color is yellowish, orangish or reddish brown. Sienna is ochre with a high iron oxide content. Unlike yellow ochres, which generally are opaque, siennas are more translucent. When a limonite, like sienna, is calcined (roasted) at high tempera tures, its water content (hydration) is eliminated and it becomes a hematite (anhydrous), like burnt sienna. Umber is iron oxide shaded with manganese ores. Umbers with the highest tinting strength are those with the highest content of manganese and iron. Calcination yields burnt umber, converting the raw umber limonite to a red hematite.

Terra verte, or green earth pigment, is derived from a mineral source but is not, in the true sense, a natural iron oxide pigment. Compositionally, it is an iron silicate with clay, producing colors that range from cold blue-greens to warmer yellow-greens.


Location of Iron Oxide Mines
During the years of industrial growth in the U.S.. iron ore deposits were discovered in the Appalachian chain between Canada and Alabama. Paint factories began to spring up in eastern Pennsylvania, eastern Ohio and New York state, where richly colored ores were dried, ground and manufactured into paint. These deposits were eventually depleted, forcing paint manufacturers to import natural iron oxide pigments to continue production. This introduced French and South African ochres, Italian siennas, Cyprus umbers and Spanish red oxides into American paint factories.

The pigment sienna owes its name to the Italian city, Siena, located in the region of Tuscany. An area of rolling hills, it is famous for the mining and production of the pigment, terra di siena, from the Renaissance until World War II. During the last two decades, as the Tuscan deposits became depleted, Italian siennas have come from other places in the country, such as Sicily and Sardinia. Small quantities of sienna also have been mined in Germany's Hartz Mountains, but these are of lesser quality.

The best ochres traditionally have come from France, yielding a range of colors from light yellow to deep red. Spain is the center for the production of natural red iron oxide pigments, while the best quality umbers come from the island of Cyprus Umbers are exported both in the pigment state or as unground ores Approximately 80% of the umber used for pigment production comes from two major suppliers in Cyprus.

On the domestic front, natural iron oxide pigments, closely resembling those historically coming from the Middle East and Italy, are mined and produced in the Appalachian range. Ochres have been mined in Georgia since 1877 and western New York is rich in iron ore deposit yielding sienna. Ochres, siennas and umbers are currently being produced at the Hoover Color Company in Hiwassee, Virginia. Located in the Valley and Ridge Province of the Blue Ridge Range of the Appalachian Mountains, Hiwassee is in the far southwestern part of Virginia.

Chuck Hoover, Jr., Vice President of Hoover Color and a geologist by training, shared a bit of the Appalachian's geophysical history with me. During the Cambric Age, 500 million years ago, present-day Virginia was under ocean water. Rich iron oxide deposits were carried by the water into valleys and deposited. Today, a section cut through the earth in this part of the Appalachians would reveal layers resembling the illustration below. For this reason, mining for natural iron oxide pigments requires that the earth be cut vertically so each layer containing pigment can be scooped and collected, exposing the layer below. When the sandy quartzite rock layer that miners call the white wall is reached, the pigment potential of that section of the mine has been exhausted.