Pigments are solid, insoluble materials that give color to or enhance the appearance of a medium. Through the absorption of varying light wavelengths, pigments can create diverse effects by transmitting light through or reflecting it off of surfaces.
The earliest known pigment types were derived from natural sources such as ground minerals and charcoal, among others. Synthetic coloring agents began to be used as early as 2000 B.C.E. These pigments included white lead, which was made from the combination of vinegar and lead in the presence of CO2, as well as calcium copper silicate, also known as Egyptian blue, which was made from malachite or copper ore-colored glass. This was followed by a surge of pigment technologies, which made it challenging to keep track of compositions.