Plaster Molder I

Lay out parting line on patterns and casts plaster molds.

What does a Plaster Molder I do?

Lays out parting line on patterns and casts plaster molds according to blueprints, sketches, and oral instructions, applying knowledge of metal characteristics, pattern contours, and pouring procedures: Locates and scribes parting line on wood, metal, or plastic patterns, using measuring instruments, such as calipers, square, depth gauge, and straightedge. Mixes plaster powder and water according to standard formula. Places cope and drag on molding table. Pours liquid plaster into drag and positions pattern in plaster up to parting line. Removes excess plaster, using straightedge, and allows mold to harden. Places cope on completed drag, and makes depressions in plaster around drag pattern to ensure accurate joining of mold halves for casting. Brushes parting agent on surfaces of mold, pattern, and flask and pours liquid plaster into cope. Separates cope and drag after specified time and removes pattern. Repairs cracks and broken edges of molds, using molder’s handtools, such as spoon, trowel, and slick. Removes excess plaster from molds, using knife or bandsaw. Joins cope and drag sections of mold together by aligning them in flask and pouring liquid plaster over them. May cut gates and risers into baked mold. May position cores in drag and assemble mold. May pour molten metal into molds, using hand ladle.