< THE CERAMIC SHELL SYSTEM
INVESTING A WAX PATTERN IN CERAMIC SHELL 1
The following series of steps outline the basic procedures for applying a water based ceramic slurry and stucco grits to a wax pattern assembly, though exact methods may vary significantly, according to individual founder’s preferences and the investment manufacturer’s recommendations.
1 WAX PATTERN ASSEMBLY
The WAX ASSEMBLY (wax pattern and running system), is prepared for investment as described in the previous section on WAXWORKING techniques. Additional patches may be cut out of a hollow wax pattern to both assist in the drainage of slurry, and the evacuation of excess stucco from the interior of the wax. Good access to the interior of the wax assembly also improves air circulation and promotes a thorough and rapid drying of applied investment.
RUNNERS and RISERS, and the POURING CUP may be used to support the assembly during investment build up and drying. If runners and cups are used to support the weight of the assembly, they may be structurally reinforced either with wax cross-members, or temporary metal bars which are inserted through the wax to allow it’s suspension on a rack for free air drying. Large scale investments may additionally have lifting rings added to metal reinforcement bars, this enables the use of a gantry hook or other lifting aid.
2 DEGREASING
The entire wax pattern and attached running assembly is DEGREASED using a proprietory alcohol. Washing also slightly ‘etches’ the wax, making the assembly more receptive to the liquid slurry. The assembly is drained of any excess alcohol and allowed to air dry. Particular attention is given ensuring the complete drying out of any interior spaces and deep undercut pockets in the wax – trapped alcohol can lead to a poor quality shell and seepage can contaminate and degrade the slurry in the holding tank.
INVESTING A WAX PATTERN IN CERAMIC SHELL 2 >
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