Plaster moulds are filled with a deflocculated slip; defloculation reverses the electric charges in the clay particals which reduces the water content in a slip to that of most plastic clays, around 30% of total weight. A common defloculant is Sodium Silicate. The remaining moisture is absorbed by the plaster leaving a sediment of clay over the entire interior surface of the mould. The excess slip is drained off and the cast can be removed from the mould soon after. This approach is used widely by industry and some studio potters.