Carmine ()also called cochineal (when it is extracted from the cochineal insect), cochineal extract, crimson lake, or carmine lake is a pigment of a bright-red color obtained from the aluminium complex derived from carminic acid. Specific code names for the pigment include natural red 4, C.I. 75470, or E120. Carmine is also a general term for a particularly deep-red color.
Etymology
The English word "carmine" is derived from the French word carmin (12th century), from Medieval Latin carminium, from Persian qirmiz ("crimson"), which itself derives from Middle Persian carmir ("red, crimson"). The Persian term carmir is likely cognate with Sanskrit krimiga ("insect-produced"), from krmi ("worm, insect"). The Persian word for "worm, insect" is kirm, and in Iran (Persia) the red colorant carmine was extracted from the bodies of dead female insects such as Kermes vermilio and cochineal. The form of the term may also have been influenced in Latin by minium ("red lead, cinnabar"), said to be of Iberian origin.
The word "carmine" has been used as a color name as early as 1799. It is a popular food color, used in yogurt, candy, gelatin, meat, and beverages including fruit juices.
History
Female Dactylopius coccus (cochineal) insects were used for their red coloring power as early as 700 BC. South American civilizations crushed the bugs present on cacti to extract the carmine they contain. Carmine pigment was extensively used by the Aztec civilization to dye textiles. It was imported later to Europe during the 16th century.
Red is a color often associated with power and social status. Through the centuries, red has been worn by tribal chiefs, kings and queens, and military officers.
Cochineal was a major source of income for the Spanish Crown. By weight, it was a far more valuable commodity than sugar, making it especially lucrative for overseas trade. As part of the triangular trade, its production and consumption were intertwined with slavery.
In European markets, the Spanish Crown had a monopoly on cochineal until 1820 when the French learned to cultivate them. Later, German and British scientists created a chemical red dye that competed with carmine. The combination of these factors contributed to the end of the Spanish monopoly and considerably lowered the price of carmine, making it accessible to a wider audience.
Production
The pigment is produced from carminic acid, which is extracted from some scale insects such as the cochineal scale (Prima), and certain Porphyrophora species (Armenian cochineal and Polish cochineal). Attempts have been made to farm cochineal.
Carmine is a colorant used in the manufacture of artificial flowers, paints, crimson ink, rouge and other cosmetics, and some medications.
Synthetic carminic acid is complex and expensive to produce. Therefore, natural cochineal carmine is predominant on the market. Its instability presents challenges for use in art and textiles, but this is less of a hindrance in the context of cosmetics.
Preparation
To prepare carmine, the powdered scale insect bodies are boiled in an ammonia or sodium carbonate solution. After separating the insoluble matter, the extract is treated with alum to precipitate the red solid. This precipitate is called "carmine lake" or "crimson lake". Purity of color is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to modify the precipitation. The traditional crimson color is affected not only by carminic acid but also by choice of its chelating metal salt ion. For shades of purple, lime is added to the alum.
To obtain 1 pound of red dye, 70,000 cochineal insects are required.
Identification and characteristics
Scientists can detect the presence of carminic acid through liquid chromatography and a diode array detector combined with a mass spectrometer with a quadruple-time-of-flight analyzer (LC-DAD-QTOF). The process is used for identifying carmine in works of art.
Scientific methods can also distinguish among the different species of cochineal used in artworks.
Wavelength
As confirmed by reflectance spectroscopy, carmine reflects mostly red light. Its hue ranges from 497 nm for a dark purplish red and 612 nm for a vibrant red.
Hue
Carmine's hue is dependent on the metallic ions present in the pigment. For instance, carmine combined with zinc or aluminum yields a crimson hue.
Translucence
The translucence of carmine depends on its binding medium. Mixed with oil, carmine remains translucent and adequate for glazes. Combined with tempera or glue, carmine turns opaque.