Roman stucco

 Traditional stucco was made of lime, sand, and water. Animal or plant fibers were often added for additional strength. Stucco was easily molded or modeled into relief decoration for walls, ceilings, and floors and was traditionally used as both an interior and exterior finish applied in one or two thin layers directly over a solid masonry, brick, or stone surface. The finish coat often contained an integral color and was typically textured for appearance.

Stucco relief was used in the architectural decoration schemes of many ancient cultures. Examples of Egyptian, Minoan, and Etruscan stucco reliefs remain extant. In the art of Mesopotamia and ancient Persian art there was a widespread tradition of figurative and ornamental internal stucco reliefs.

In Roman art of the late Republic and early Empire, stucco was used extensively for the decoration of vaults. Though marble was the preferred sculptural medium in most regards, stucco was better for use in vaults because it was lighter and better suited to adapt to the curvature of the ceiling.  Stuccowork grew in popularity in late Republican and early imperial Rome as a result of the construction boom associated with brick and cement construction. 

"Artists working in Roman Italy created expansive stucco schemes in private homes, tombs, and public buildings, particularly in baths. On walls, architectural members such as balustrades, column capitals, pilasters, columns, cornices, and frieze borders were fashioned in stucco and integrated into painted schemes. The stucco elements enhanced the two-dimensional decorative surfaces with projecting architectural members, adding a play of light and shadow to the interior spaces. The pieces in high relief were secured to the walls with metal rods or nails. Some forms were molded before they were attached to the walls, but other shapes and designs, such as cornices or frieze borders, were stamped into semi-dry plaster after application to the wall or ceiling. The stamped patterns imitated the egg-and-dart and vegetal borders carved on monumental architecture, a fashion that is also seen in contemporary Roman wall paintings, particularly those painted in the Second Style." - Metropolitan Museum of Art.

Read more about it at:

https://www.metmuseum.org/toah/hd/stuc/hd_stuc.htm

To see many of the stuccos in the tepidarium of the Forum Baths in Pompeii:

https://commons.wikimedia.org/wiki/Category:Forum_Thermae_(Pompeii)_-_Stuccos_in_Tepidarium

1st century CE stucco relief of a woman with deer from a Roman villa that I photographed at the Art Institute of Chicago

Stucco reliefs that I photographed in the tepidarium of the Forum Baths in Pompeii in 2007

Stucco relief fragment with standing figure identified as the Emperor Antoninus Pius on the basis of his similarity to known portraits. Before him kneels a barbarian suppliant. 138–161 CE, Roman, The Metropolitan Museum of Art in New York

Stucco relief panel depicting nude female, 2nd half of 1st century CE, Roman, The Metropolitan Museum of Art in New York

Stucco relief panel depicting nude follower of Dionysus, 2nd half of 1st century CE, Roman, The Metropolitan Museum of Art in New York

Stucco relief panel depicting maenad with tympanum, 2nd half of 1st century CE, Roman, The Metropolitan Museum of Art in New York

Stucco relief panel depicting Eros, 2nd half of 1st century CE, Roman, The Metropolitan Museum of Art in New York

Stucco relief panel depicting a painther frequently associated with Dionysus, 2nd half of 1st century CE, Roman, The Metropolitan Museum of Art in New York