What is the use of boxing an impression?

BOXING WAX AND BEADING WAX  USES  Used to build up vertical walls around the impression, in order to pour the stone and make a cast. The procedure is known as boxing.  SUPPLIED AS  Boxing wax as sheets, beading wax as strips. ADVANTAGES OF BEADING AND BOXING  Preserves the extensions and landmarks.  Controls the thickness of the borders.  Controls the form and thickness of the base of the cast.  Conserves the artificial stone.  PROPERTIES  They are pliable and can be adapted easily. A slight tackiness allows it to stick to the impression. Note: The terms carding wax and boxing wax have been used interchangeably. Carding wax was the original material on which porcelain teeth were fixed when received from the manufacturer. Boxing wax is a more acceptable term.