A discussion of the physical properties of plaster (the solution recrystallization of CaSOub>4 Hub>2O) and of those physical properties which affect conservation (solubility, porosity, absorbency, fragility, and durability) introduces a general outline of the methods employed to clean, impregnate, join, and consolidate a large number of 19th century plaster casts and molds. After vacuuming and brushing, erasers were used to remove surface dirt; 3% Rohm and Haas Acryloid B-72 in toluene was the usual impregnating resin, using a vacuum system where possible. The consolidation of a badly damaged life size plaster statue, Abraham Lincoln by D. C. French (1916), is described; a polyester resin (Kopper's 1060-5 resin and hardener) and fiberglass mat comprise an interior lining and support. 14 notes.