We have seen sculptures that show off the natural color of the material they are made from like the marble and bronze sculptures.
However, some sculptures are colored. The most unadorned, white marble sculptures that were unearthed from archaeological sites in the 16th century were once decorated with a wide variety of colors. They are called polychrome sculptures. The polychrome sculpture is originally associated with Ancient Greece and Rome and describes all manners of pigmented decoration, gilding, and the application of varied colors to a three-dimensional surface. Thanks to scientific advances in the study of pigments and other aspects of conservation, art historians have been able to authenticate the former coloration of countless historic objects.
The pigments that were used to polychrome sculptures came from one or more powdered minerals found in nature. There are some organic pigments which have been extracted from plants. The variety was quite limited. The ochre colors were extracted from iron oxides. They gave yellow and brownish shades. The bright colors were most expensive as they were extracted from pure and less common minerals. Cinnabar- Mercuric sulfide found in the mercury mines, was a popular, expensive red mineral pigment. Other minerals that were commonly used as colors were-
Orpiment– Arsenic sulfide mineral used to produce yellow pigments;
Azurite– Copper carbonate hydroxide mineral. It gave a deep blue shade to the sculptures. This was an expensive pigment.
Malachite – A green copper carbonate Mineral closely related to azurite – and just as expensive.
Black was obtained from burned bone and vine.
A pigment has to be used with a binder, which lets the color adhere to the surface to be colored. These are natural glues and most commonly come from eggs, milk, and bones. Polychroming a sculpture is not just coloring. It is also shading in light and dark colors.
Common examples of polychrome sculptures include decorated Christian altarpieces or the German limewood sculptures of the Renaissance-era.