A method of pressurizing a container usable for an aerosol dispenser. The method comprises providing a pressurizeable outer container and complementary valve cup, at least one having a channel into the container. A manifold is brought into sealing relationship with the channel of the container. Propellant is supplied from the manifold, goes through the channel and into the container. While the manifold is still sealed to the container, the channel is sealed shut to maintain the pressure. Sealing may be accomplished by sonic or ultrasonic welding.