Pasty composition of soft and plastic consistency spread or daubed on a surface where it hardens. It was traditionally made of burnt limestone (quicklime or calcium oxide) mixed with sand, water, and hair to provide a smooth surface fit to receive decorations. Plaster of Paris is lime sulphate (gypsum) deprived of its natural water-content by heat, ground to a fine powder and mixed with water to form a paste: it sets quickly, expanding at the time of setting, a peculiarity that not only makes it useful for filling cracks, but causes it to take sharp and delicate impressions from a mould. See also stucco.
W. McKay (1957);Nicholson (1835);W. Papworth (1852)