The rotary evaporator or "rotovap" is an expensive piece of apparatus that needs to be used with great care. If you follow the instructions carefully, it is the fastest, most efficient and most environmentally friendly way of removing a volatile solvent from a non-volatile sample. It is standard equipment in a modern chemistry laboratory. The rotovap works by increasing the rate of evaporation of the solvent by: (1) reducing the pressure to lower the solvent boiling point, (2) rotating the sample to increase the effective surface area (3) heating the solution. Rotary evaporators are distillation units that incorporate an efficient condenser with a rotary flask system. As the flask containing the solvent is rotated it continually transfers a thin layer of liquid over the entire inner surface. This gives a very large surface area for evaporation that is effected by heating from the accessory water or oil bath. They are the ideal tools for many everyday laboratory applications including: Concentration of solutions Reclamation of solvents Vacuum drying of wet solids Degassing liquids