Abstract: A fugitive pattern, such as wax or other meltable pattern material, residing inside of a refractory mold, which can be unsupported or supported in a particulates bed, is removed by discharging steam or other condensable vapor that may include a surfactant inside the mold to contact and melt the pattern while an exterior of the mold is subjected to a non-condensing gas atmosphere such as air outside of the mold. Regardless of whether the condensable vapor includes surfactant or not, the mold can be tilted relative to gravity and rotated while it is tilted to improve the pattern removal. Condensable vapor is condensed inside the mold where the vapor has contacted the pattern while the exterior of the mold remains free of condenate. The condensed vapor and melted pattern material are drained out of the mold with the surfactant, if present, improving drainage.

Abstract: A method is provided for removing a fugitive pattern, such as wax or other meltable pattern material, residing inside of a refractory mold by discharging condensable vapor such as steam inside the mold to contact and melt the pattern while an exterior of the mold is subjected to a non-condensing gas atmosphere such as air outside of the mold wherein the condensable vapor inside the mold and the atmosphere outside of the mold are at substantially the same pressure. Condensable vapor is condensed inside the mold where the vapor has contacted the pattern while the exterior of the mold remains free of condenate. The condensed vapor and melted pattern material are drained out of the mold. The condensed vapor can be discharged initially inside a hollow sprue of a fugitive pattern assembly to melt the sprue and then inside the mold to melt the patterns of the pattern assembly.