Abstract: Method for slip casting toilet bowls and as mould for casting ceramic material in slip form, including a compartment having an air impermeable wall and arranged, in the casting position of the mould, so that when the mould is filled with slip air is trapped in the compartment. The compartment is located at a region where casting is not to occur and the trapped air not only achieves this but also prevents the surface of the compartment from becoming wetted, thereby making subsequent cleaning easier. The compartment may be formed either in a plaster mould part and its surface rendered air impermeable, or in a separate part made of air impermeable material, and assembled with the plaster mould parts. The mould is particularly suitable for casting a water-closet bowl, the compartment being located at the region where the open top of the bowl is formed.