system 14 from a hollow sprue 22 which is made from the same pyrolizable foam as the pattern 8 and is likewise coated with a thin gas permeable ceramic layer 25 like that coating the pattern 8 the sprue 22 has 1 a mouth 24 at one end for receiving molten metal 2 a hollow portion 26 extending from the mouth 24 to a level below the pattern 8 and 3 a discharge outlet end 30 for discharging the molten metal from the sprue the discharge end 30 engages a piece of solid foam 28 that extends from the discharge end 30 of the sprue 22 to the inlet 32 to the gating system and has a thin porous ceramic coating 29 thereon the hollow portion 26 comprises a fugitive foam wall 34 defining an internal flow channel 36 a metal fill cup 38 positioned in the mouth 24 of the sprue 22 receives melt from an overhead ladle or furnace not shown and directs it into the flow channel 36 it is also known to use a similar sprue arrangement but wherein the hollow portion 26 is replaced with solid foam after pouring and solidification the metal left in the sprue i e the u201c sprue metal u201d and in the gating system is cut away.