The Truth About Caramel Color

Caramel color or caramel coloring is a water-soluble food coloring. It is made by heat treatment of carbohydrates, in general in the presence of acids, alkalis, or salts, in a process called caramelization. It is more fully oxidized than caramel candy, and has an odor of burnt sugar and a somewhat bitter taste.
In general, the pigments used by Greek and Roman painters included the following:

Red Colours

Yellow red was obtained from the naturally occurring arsenic compound Realgar. For bright red, artists used a material known as "Dragons Blood". Described by Roman historians as the blood collected after the fighting of dragons and elephants, this was a common colourant until the modern era. It came from a gum resin obtained from a tree in South East Asia. But the most highly prized red pigment of the time, ten times more expensive than red ochre, was Vermilion. Known to the Romans as Minium, this orange-red hue was produced from a mineral ore called Cinnabar (Mercuric Sulfide) and appeared in the Mediterranean area about 1500 BCE. Probably mined in central or southern Europe, it was later superceded (8th century CE) by a much superior version from China.

Purple Colours

For purples and similar hues, Greek and Roman colour palette featured pigments like Indigo, obtained from the Indigofera plant family, and Madder from Madder plants. Woad (from the dyerswoad herb) might also have been used. Although principally employed as textile dyes, by Classical Antiquity these ink-type colourants had been developed for use in painting, especially glazing. The most popular of the purples was Tyrian purple, a hue produced from shell fish by the Phoenicians and made famous as the colour worn by Roman Caesars. It was also used by artists in Antiquity as a glazing pigment. Tyrian purple was available in tones of violet, true purple, and a very deep crimson. However, use was limited by its huge production costs.

Blue Colours

For their blue palette, Classical painters relied on the same pigments as the Egyptians: notably Azurite and Egyptian Blue. Azurite was a greenish blue pigment whose name stemmed from the Persian word "lazhward" meaning "blue". It was chemically related to the green pigment malachite. Egyptian Blue (Frit) was a dark blue pigment used throughout antiquity for use on a range of mediums such as stone, wood, plaster, papyrus, and canvas. It was later superceded in the 6th century CE by Ultramarine, the most fabulous blue in the history of art. An inferior version of Ultramarine (Lazuline Blue) was actually in use in both Greece and Rome, but it wasn't until the 500s that the Persians developed the key process for the conversion of Lapis Lazuli into Ultramarine.

Green Colours

Among the green pigments used in Classical times were Verdigris, a synthetic copper green, (the name means "green of Greece"); green earth, a natural colourant of varying hue known in other eras as Terre Verte, Stone Green, Verdetta, and Celadonite; Egyptian Green, a sister of Egyptian Blue (see below); and the bright green Malachite, also known as Mineral Green or Verdeazzuro.

Yellow Colours

For their yellows, Greek and Roman painters used Massicot and Naples Yellow, as well as the traditional Orpiment. Massicot came from lead oxide, while Naples Yellow - a warm yellow pigment - derived from Lead Antimoniate and appeared at the same time as Vermilion. Naples Yellow (also called Giallorino) was reportedly obtained from Mount Vesuvius above the Bay of Naples. Orpiment was a rich lemon hue known to colour-makers since 3100 BCE.

Brown Colours

As a rule, brown hues were obtained from burnt and raw forms of clay pigments such as Sienna and Umber. In its raw state, Sienna, which contains iron and manganese, resembles a yellow-brown ochre: roasted or burnt it turns it a reddish brown. Similarly, Umber, a clay pigment used since Paleolithic times, is naturally a dark yellowish brown. Roasted or burnt Umber is coloured dark brown. These two pigments were the most stable colours on the Classical painter's palette.

White Colours

A major addition to the Classical colour palette was Lead White. Very fast drying, with the warmest masstone of all the white colourants and a heavy consistency, it remained one of the key white pigments until the 19th century. Other white colourants used included Gypsum, and Chalk.

Black Colours

For their black hues, Greco-Roman painters relied on Lamp Black and Carbon Black (charcoal) and a new Ivory Black, obtained from burning bones or ivory.