An applicator unit for use in applying a substance to a surface, the applicator unit comprising: a body unit to which a pressurizable container is in use attached; and an outlet unit which includes an applicator element to which substance is dispensed and a valve member which is movably disposed relative to the applicator element between a first, closed configuration in which the outlet unit is closed and a second, open configuration in which the outlet unit is opened such as to establish a communication path between the container and the applicator element, wherein the valve member is configured to be moved to the open configuration on pressurisation of the container, thereby providing for dispensing of substance to the applicator element.