Abstract: A castable slip of a bimodal distribution of silicon carbide particles is prepared, the slip preferably containing a water miscible curable resin. A shaped body is cast in a plaster of paris mold which also preferably contains a small amount of a water soluble polymer. The casting and mold are then heat treated to increase the strength of the green casting. In a preferred embodiment of the invention the resin in the slip is cured by the heat treating step. The mold is then removed by decomposing the mold material, preferably by dipping the mold in acid to attack the mold material (e.g. the water soluble polymer or the plaster of paris itself). The cured resin in the casting is sufficiently resistant to attack by the acid to survive the mold removal. In an alternative embodiment the silicon carbide body is heated to a sufficiently high temperature (e.g. 650.degree.-750.degree. C) to slightly oxidize the SiC and to strengthen the green casting.