in an investment casting process wherein molds or cores are prepared by forming them around a polymer pattern and then dissolving the pattern with a solvent , solvent losses can be reduced by heating the mold or core before contacting it with the solvent to reduce the amount of solvent adsorbed in the mold or core . an improved process comprises : forming the mold or core around the pattern ; heating the mold or core ; dunking or spraying the mold or core with the solvent until the pattern is dissolved ; placing the mold or core in a drying chamber in the path of circulating heated air ; cooling the air to condense the solvent ; recovering the condensed solvent ; and reheating the air until it is no longer saturated with solvent and recycling the air to the drying chamber . the preliminary heating step can reduce solvent losses by 66 percent and the entire improved process can reduce solvent losses by about 90 percent .