Plastic tooling, the fabrication of molds and fixtures for the molding of plastic and other items, requires a series of operations to achieve the final usable molds. 1. A pattern is made to the requisite drawing. Wood, plaster, other easily formed material can be used. This pattern must then be smoothed and sealed, preferably with a moisture curing urethane varnish, based on resin such as "Arothane" 156XA 450 (ADM). A release agent such as wax, silicone or PVA completes the preparation for use. 2. A mold frame of suitable size to accommodate the cavity is prepared. A shallow wood box is adequate where molding pressures are low, but a steel container is necessary for higher pressures as in compression molding. It should be remembered that a good strong mold frame will prevent cracking or breakage of the plastic mold during the pressure cycle. 3. The resin used in casting the cavity is prepared, the catalyst and filler added, and a layer cast in the bottom of the frame. This layer must e at
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