The mechanism of the formation of an internal bulge appearing as a local increase in wall thickness in the slip casting of large potteries was investigated to prevent occurrence of cracks in dried green bodies. Because it is not easy to observe moisture suction and deposition inside a plaster mold, a simple plate mold was used in the experiment. Moisture suction in the joining region during the casting was enhanced by breaking the alignment of particles due to the collision between the fronts of the slurry; thus, the wall thickness in the joining region increased owing to the acceleration of the growth of deposit. An internal bulge was formed by the difference in the growth of deposits between the joining and peripheral regions. It was found in the slip casting of a model washbasin that the occurrence of internal bulge is prevented by vibrating the plaster mold during the pouring of the slurry.
2005 The Ceramic Society of Japan