How Is Oil Paint Made?

Brilliant ground pigments combine with oil to make oil paints.

Oil paints are made from ground pigments suspended in oil. A pigment is a colored material that can come from a variety of sources. Manufacturers select artist oils based on their stability and drying times. Artist oils are refined to remove impurities, and are mixed with individual pigments to form oil paints. Early artists made their own oil-based paints. Dry powdered pigments are available in art stores for those artists who prefer to mix their own blends.

Paint History

Prehistoric artists used clay dug from the earth or charcoal from burnt wood mixed with water or other liquids to make paint. Both the sources and suspension mediums of pigments evolved over many centuries as artists sought to improve the stability and color range of materials. Oil paints were first developed in the 15th century. Artists sought out new materials that dried slower than the tempera paint used at the time. By the 1600s, many artists used oil paints.

Natural Sources

Early pigments came from natural sources. Many pigments were literally earth-colored. Yellow ochre originated from clay earth that contained a yellowish mineral called goethite. Red-tinted iron oxides mixed with clay made red ochre. Raw umber also came directly from the ground.

Artists made blue indigo pigment from the indigo plant's leaves. Madder plant (Rubia tintorum) roots gave madder lake paint its signature crimson hue. Certain beetles released crimson color when crushed, and the ground bugs colored carmine lake pigments. Modern synthetic substitutes have replaced many of the old pigment sources.

Synthesized Pigments

Many consider Prussian blue pigment, first discovered around 1724 during experiments with oxidizing metals, to be the first modern pigment. A chemical method of creating crimson color in 1868 replaced madder root. Chemically synthesized pigments such as cadmium yellow or red appeared in the early 20th century. Titanium white, developed in the 1920s, has excellent opacity and stability. The pigment is used in toothpastes and cosmetics as well as oil painting.

Suspension Oils

Artists and manufacturers usually use linseed oil when they blend pigments into paint. Refined linseed oil allows paints to dry slowly and avoid cracking. The oil is stable; it does not break down over time, and does not yellow with age. Poppyseed oil is another artist oil. It is completely colorless and useful for preserving the luminance of pale pigments. Walnut oil is good for blending, but is used less frequently as it is costly to manufacture.

Mixing and Testing

All ancient artists mixed their own paints, and some contemporary painters also make their own blends. The process of creating oil paint is similar to mixing wet and dry ingredients in cooking. Place a pile of dry pigment on a sturdy glass or other smooth, non-reactive surface. Poke a hole in the center of the mound and add oil slowly into the hole. Use an artist's palette or spatula to smear together the dry and wet ingredients. Add enough oil so the paint has the consistency of butter. Factories mass-produce oil paints using similar techniques.

Store-bought paints have good consistency from one tube to the next. Manufacturers test the paints for light fastness and acceptable texture. Bargain varieties of oil paints have less pigment and more oil in a tube. Although the paint tube costs less, the artist ends up needing more paint and the savings vanish.

References

• Pigments through the Ages: Choose a time period
• "The Artist's Manual"; Friso ten Holt; 1980
• Pigments through the Ages: Pigments in oil