A casting can only be as accurate as the cavity it was poured into. Long before molten metal reaches the mould, decisions about the moulding sand have already shaped the result: whether gases escape or get trapped, whether the surface comes out clean or with sand fused to it, and whether thin sections hold their shape or wash away under the metal stream. Many foundries chase porosity, rough surfaces or veining at the pouring stage when the root cause sits in a sand specificat
