A roller dispenser for dispensing liquids has a headpiece mounted on a container. A barrier component is fitted between the headpiece and the container. The barrier component and the headpiece have respective annular seal elements which can fit together to form a plug seal, isolating the underside of the roller from the liquid supply when the barrier and headpiece are moved close together. The barrier and headpiece can be moved apart by a cam action, e.g., a thread, in order to allow liquid onto the roller.
