Stucco is a generic term for all types of external plaster with a smooth finish (as opposed to render), or used for mouldings. It was usually a mix of lime, sand, and brick dust or stone dust, and later Portland cement. When decorated with incised or moulded patterns, it is called 'pargetting' or 'pargeting'.
Various proprietary products were offered. These included Liardet's cement (from 1773), Parker's Roman cement (1796), Hamelin's mastic (1817) and Portland cement (1824). The last of these was the only one to survive.
Stucco was originally used as an all-over finish but by the end of the 19th century was used for decoration only.
The perfect stucco looked like real stone. Earlier on this was often not achieved and then the stucco was coloured with a solution of limewater and copper sulphate ('copperas'), or else painted, at least with matt stone-like colour, but often grained to look like stone and sometimes coloured to suggest lichen and age. Later on, the plaster colour was improved and was more often left unpainted.
Stucco could be left plain, or incised in a variety of patterns:
Stucco was also used as an alternative to terracotta for decorative plaques.