Patented J. Keating 1846. A hard finish plaster used for interior stucco decoration. It was similar to Keene's cement plaster, except borax was used as an additive to finely powdered gypsum in place of alum, to accelerate the setting. Plaster of Paris was soaked in a solution of borax (sodium borate), cream of tartar (potassium hydrogen tartrate) in water and subsequently calcined. Parian cement was free working and possessed good tensile strength. It had high strength and could be polished. It was a hard-finish plaster, used neat for mouldings over a float coat of one part Portland cement to three parts sand. It was also used for flooring and for imitation tiling, as well as for sgraffito. Synonyms: gypsum cement; hard-finish plaster. Ashurst (1983); Museum of Fine Arts, Boston (2000); RS Means Building Glossary (undated); Trench (2000). [J. Cassar, R. de Angelis]