a method and apparatus for controlling the dispersion of molten metal in a mold cavity is disclosed , the control facilitated by a localized densification of foam in a lost foam casting operation for producing metal castings , wherein the filling of regions of the mold cavity which do not lend themselves to castability is maximized , an amount of backfill and casting defects are minimized , and a flow pattern of molten metal and material properties of the resulting casting are optimized .