US Patent 7278465 Investment casting slurry composition and method of use

An investment casting method involves producing a casting shell by applying a hardenable moist mixture to a sacrificial pattern. To hasten the hardening of the moist mixture to create the shell, a stucco coat is subsequently applied to the mixture. In some cases, the stucco coat comprises a drier mixture of the elements used in the moist mixture. The drier mixture preferably includes a material that alters the alkalinity of the underlying moist mixture. In some cases, the stucco coat also includes an amorphous mineral silicate. Once the shell is created, a molten metal is introduced into the shell to replace the sacrificial pattern, thereby producing a metal cast item.