Scagliola is a building technique that uses certain materials to imitate structures made of marble. The term "scaglia" is Italian, meaning "chips." It also denotes the place origin for this architectural feature: the country of Italy.
There is some evidence that scagliola was used as far back as ancient Roman times. The style, however, did not come into prominence until the 17th century. At this time, inhabitants of the central Italian region of Tuscany eschewed the expensive marble inlays favored three centuries before by the House of Medici, a rich and powerful family based in one of the region's cities, Florence. The method of making such inlays is called pietra dura, which involves cutting rocks such as marble for the creation of images. The solution to the costly enterprise was to replicate it using less expensive material, and as a result, scagliola spread throughout the European continent in the 18th and 19th centuries, particularly to Great Britain.
Scagliola usually consisted of mixing gypsum, a type of alabaster mineral better known as plaster of Paris, with natural pigments, and animal glue was applied as an adhesive. This mixing method produced the color characteristic of this architectural style. After it dried, the entire structure was usually polished with wax and flax oil for durability and brightness, respectively. Although scagliola was applied to several kinds of structures, the most popular application was to stucco columns, which were exterior decorative columns of high aesthetic and practical value that were a dominant feature of the Baroque architecture produced in Italy at the time.
The Scagliola style is comparable with a similar technique called terrazzo, which also involves the imitation of marble. The style consists of stone chips placed in a binding material and leveled to create a smooth and intricately spotty surface. Like scagliola, the origin of terrazzo can be traced to Italians, specifically construction workers based in Venice who wanted to cut down on the cost of their flooring jobs. Terrazzo is most commonly used for floors and counter tops, particularly patio and panel surfaces.
Architects and construction workers throughout the Western world were drawn to scagliola for certain advantages. It produced a more alluring texture and color than real marble due to its unique mixture of materials. Also, because of the integration of the pigment in the building material rather than painting over the structure, its color application was more impervious to scratching than other kinds of painting jobs. Ironically, the scagliola practice declined for the same reason that it gained ascendancy: cost. By the end of the mid-20th century, it had virtually disappeared mainly due to the rise of relatively cheaper mass-produced building materials.