Brazing joins material by heating it in the presence of a filler metal having a melting point above 840°F (450°C) but below the solidification temperature of the base metal. A variety of processes can provide the heat required for brazing. The filler metal used distributes itself between the closely fitted surfaces of the joint by capillary action. Parts must be properly cleaned in order to achieve a good quality joint. To prevent excessive oxidation during brazing, the parts must be protected by either flux or atmosphere during the heating process. The parts must be designed to provide a capillary for the filler metal when properly aligned, and a heating process must be selected to provide the proper brazing temperature and heat distribution. The typical brazed joint has a relatively large area and very small gap. In the simplest brazing application, the surfaces to be joined are cleaned to remove contaminants and oxides. Next, they are coated with flux, a material capable of dissolving solid metal oxides and preventing new oxidation. When the joint is heated, the flux melts, cleaning the base metals and protecting them against further oxidation by a layer of liquid. Brazing filler metal is then melted onto the edge of the joint. Capillary attraction between the base metal and the filler metal is much higher than that between the base metal and the flux, which is displaced by the filler metal. The joint, when cooled to room temperature, will fill with solid filler metal, and the solid flux will be found on the joint periphery.