The plaster mould draws water from the poured slip to compact and form the casting at the mould surface.

But both left behind the plaster moulds of their real features which were made to make the masks.

Its rigidity limits its use in moulds, and plaster moulds are unsuitable when undercuts are present.

Air conditioning was added to the building, necessitating drop ceilings to make room for the ducts, which obscured the original plaster moulding in the interior.

It was adaptable to mass-production techniques for stock shapes, although the plaster moulds had a limited capability for re-use.