Blue is one of the three primary colors, along with red and yellow. It occupies a special place in human culture, evoking feelings of calmness, serenity, and openness. The search for new blue pigments drove innovations in art, science, and trade throughout history. Modern chemistry has uncovered the chemical composition of traditional blue pigments as well as given artists access to new manufactured blues. So what are the pigments that can produce the color blue?
Traditional Blue Pigments
Humanity’s earliest blue pigments came from readily available natural minerals. Here are some of the most important:
Azurite
Azurite is a vivid blue copper carbonate mineral (Cu3(CO3)2(OH)2) found in mineral deposits around the world. It has been used as a blue pigment since ancient times in China, Egypt, and the Middle East. The early Roman Empire prized azurite as an expensive luxury import.
Azurite produces a bright blue but it is sensitive to heat and humidity. In the presence of moisture, it turns green as the copper ions convert to malachite. This made it challenging to use in fresco paintings. It works best when tempered and used in oil paint or tempera.
Ultramarine
Ultramarine refers to an intense blue pigment made by grinding lapis lazuli into a powder. Lapis is a rare semiprecious stone consisting of lazurite, calcite, and pyrite that has only been found in a few locations such as Afghanistan.
The cost of importing lapis lazuli made ultramarine more valuable than gold in medieval times. Patrons often demanded its use despite the expense. Artists reserved ultramarine for the drapery of Mary and Christ figures.
| Pigment | Source |
|---|---|
| Azurite | Copper carbonate mineral |
| Ultramarine | Ground lapis lazuli |
Renaissance and Baroque Blues
The Renaissance desire to paint realistic skies, seas, and visions of heaven spurred the quest for better blue pigments. Painters and alchemists experimented to find stable intense blues.
Smalt
Smalt is a blue pigment made by grinding blue cobalt glass into a fine powder. Venetian glassmakers perfected the recipe for cobalt blue glass in the Late Middle Ages. The coarse particles gave a deep blue with a granular texture.
Smalt was the first stable intense blue pigment available in Europe. It rapidly replaced ultramarine for widespread use during the Renaissance. However, it would degrade to a pale gray over time in oil paintings due to absorption of the oil medium.
Indigo
The dye indigo has been used to color fabrics blue since ancient times. Pigment can be made from indigo by precipitating the soluble dye into insoluble particles. Indigo pigment was rarely used in European painting during the Renaissance due to competition from smalt.
Indigo’s importance grew as a pigment in the 17th and 18th century as smalt was found to fade. The calm midnight blue became popular for fashionable clothing and decorative arts. It also found new use in European oil paintings.
| Pigment | Source |
|---|---|
| Smalt | Ground cobalt blue glass |
| Indigo | Plant-derived dye |
Modern Synthetic Blues
The 18th and 19th century ushered in a revolution in blue pigments with the Industrial Revolution. Manufactured modern colors delivered consistent intense blue shades.
Prussian Blue
Prussian blue was the first modern synthetic pigment, discovered by accident in 1704. It is made by oxidizing iron with animal products. This ferrous ferrocyanide compound creates an extremely stable vibrant blue.
By the mid-18th century, Prussian blue was being manufactured in large quantities for use in oil and watercolor painting. Delftware potteries developed Chinese-blue and white porcelain using Prussian blue designs. Prussian blue is still commonly used by painters today.
Phthalocyanine Blue
Phthalocyanine blue describes a family of synthetic organic blues that were first created in the 1930s. The most common variant used in art is phthalocyanine blue BN. These pigments have excellent hiding power and stability.
Phthalocyanine blues offer a range of shades from greenish aqua to a deep midnight blue. They eventually replaced Prussian blue as the most popular blue for manufacturing paints, inks, and plastics. Artists appreciate their versatility.
| Pigment | Source |
|---|---|
| Prussian blue | Synthetic iron ferrocyanide |
| Phthalocyanine blue | Synthetic organic compound |
Other Notable Blue Pigments
Beyond the major blue pigments described above, there are a few other interesting blues used in art over the centuries:
– Egyptian blue: The first artificial pigment, made by heating sand, copper, and alkali salts. Used from 2500 BC until the Classical period.
– Cobalt blue: Invented in the early 19th century, cobalt aluminate spinel creates pure tones ranging from sky blue to navy. Toxic to manufacture.
– Cerulean blue: A complex silicate invented in the 1860s to provide a highly chromatic blue between azure and cyan.
– Manganese blue: Discovered in the 1930s, these pigments based on barium manganate were used for paints and plastics.
The quest for stable vibrant blues led to major technological innovations. Each new discovery offered artists more options to create their ideal shades of blue. From minerals to synthetics, the palette continues to expand.
Conclusion
Blue is a beloved color across human cultures. But stable blue pigments have historically been challenging to produce. Early natural mineral blues like azurite and lapis were rare and expensive. By the Renaissance, smalt and indigo emerged as the first widespread blue pigments.
The 18th century saw a revolution with the invention of synthetic blues such as Prussian blue and cobalt blue. In the 20th century, phthalocyanine and manganese blues provided artists with a full spectrum. The story of blue pigments illustrates how art, science, and technology intersect throughout human history.
