Abstract: Apparatus and method for the differential pressure, countergravity casting of a melt of molten metal, such as nodular iron, containing a fugative alloyant, such as a magnesium nodularizing agent, susceptible to rapid loss from the melt over time wherein a source of the alloyant is so disposed on a lower portion of each mold as to contact the melt and replenish the alloyant content thereof when the lower mold portion of each mold is immersed in the melt for casting. An effective level of alloyant is thereby maintained in the melt throughout the casting of a plurality of molds in succession from the melt.

Abstract: A melt-holding vessel includes a melt-holding chamber defined by a bottom wall and upstanding side wall of refractory material. The side wall includes one or more insulating air pockets located in such a manner relative to the chamber as to substantially reduce heat loss from the melt in the chamber by conduction through the side wall.