Most foundries do not have an adequate mold wash (refractory coating) quality control program, in spite of the fact that the refractory coating forms the critical mold-metal interface. Proper wash storage, reconstitution prior to delivery to the foundry, and foundry stirring are all critical details of a proper quality assurance program. Special attention must be given to the wash mixers and stirrers; and recommendations are presented. Testing a refractory coating's Baume is not sufficient to control its consistency or its performance. The more powerful technique of specific gravity determination is discussed, as well as its use to control additions to the wash and to identify wash constituents. Specific gravity testing lends itself to the use of "precontrol" SPC charting.
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