Abstract: A process of enameling the inside surface of hollow vessels, which have two openings at opposite points. In a hot-water reservoir to be enameled these openings are provided at both ends. One opening is connected to a vacuum pump and the other to a conduit which incorporates a valve and leads to an enamel slip reservoir. In a first step, a vacuum pump is operated to pre-evacuate the interior of the hollow vessel so that air is removed from the pores at the inside surface of the hollow vessel. In this step the valve in the slip conduit remains closed. When the vessel has been preevacuated to about 40 to 80 torrs absolute, the valve is opened so that slip flows suddenly into the hollow vessel and fills the pores while the evacuation is continued and slip is sucked into the hollow vessel until the slip emerges from the opening through which the hollow vessel is being evacuated.

Abstract: Apparatus for coating articles with enamel slip comprises an evacuatable container 1, which is divided in a vertical plane into parts 2, 3, which are movable toward and away from each other. The articles 29 to be coated are suspended in a row from an endless conveyor track and are introduced into the container 1 when its parts 2, 3 have been moved apart to open the container 1. The container 1 is then closed. In the closed container, the suspension means are held between soft seals 12, 13 which cover the confronting edges of the container parts 2, 3. When the container 1 has been closed, the air contained therein is sucked off and slip is sucked into the container. As soon as the coating operation has been completed, the slip is drained from the container 1 and the latter is then opened and the coated article is removed.