A light, malleable plaster-like substance made from dehydrated lime (calcium carbonate) mixed with powdered marble and glue and sometimes reinforced with hair. It is used for sculpture and architectural decoration, both external and internal. In a looser sense, the term is applied to a plaster coating applied to the exterior of buildings, and the words plaster and stucco are often used more or less interchangeably; in strict usage of the terms, however, plaster can be differentiated by the fact that it is made from calcium sulphate. Stucco has been known to virtually every civilization, and in Europe it was exploited most fully from the 16th century to the 18th century, notable exponents being the artists of the School of Fontainebleau and Giacomo Serpotta. By adding large quantities of glue and colour to the stucco mixture, stuccatori were able to produce a material that could take a high polish and assume the appearance of marble. Indeed, sometimes it is difficult to distinguish from real marble without touching it (marble feels colder).