30 in order for the pressure to reach the molten metal the pressure must travel both a through the inert material 14 and across the ceramic coating on pattern 8 and b down through the inert material 14 up into the pressurized compartment head section 32 and thereinto the molten metal 30 in this manner the application of pressure to the molten metal 30 occurs at relatively the same time resulting in the significant reduction of pressure differential at the molten metal front therefore the presence of the permeable sub member advantageously allows for an increased pressurization rate while avoiding the development of a differential pressure at the molten metal front that would result in metal penetration defects the invention has a further advantage in the fact that the pressure equalization member is reusable thus a new pressure equalization member need not be inserted after every casting in another embodiment the pressure equalization member 16 may be constructed of a selectively permeable material the permeability being equivalent to the permeability of the finely divided inert material 14 the selectively permeable material may be a porous high temperature ceramic material or the like in this embodiment the molten metal front is stabilized as the pressure traveling through the pressure equalization member 16 is forced to travel at the same rate as the pressure traveling through the finely divided inert material 14 in still another embodiment of the invention the pressure equalization member 16 is constructed of impermeable material while the pouring cup 18 is constructed of a selectively permeable.