This slip is poured into the space between plaster of Paris molds. The toilet bowl, rim, tank and tank lid require separate molds. The molds are assembled and set up for filling and the slip-filled molds sit for about an hour after filling. This allows the plaster molds to absorb moisture from the slip, which makes it semi-solid next to the mold surfaces but lets it remain liquid further from the surface of the molds. Then, the workers remove plugs to allow any excess liquid slip to drain from the cavities of the mold (this excess slip is recycled for later use). The drained-out slip leaves hollow voids inside the fixture, using less material to keep it both lighter and easier to fire in a kiln. This molding process allows the formation of intricate internal waste lines in the fixture; the drain's hollow cavities are poured out as slip.