Box Cast

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Box casting is a basic kiln-casting technique in which fire-resistant plaster is poured into a wooden or metal frame (box), which is then used as the mold (treatise §10.2, Bullseye TipSheet 5). Since creating the mold involves simply “pouring plaster into the frame and allowing it to set,” the process is straightforward and widely used as an introduction to casting techniques. The standard peak temperature for Bullseye glass is 815–840°C (according to Chikaoka’s table). It is suitable for creating flat plates, blocks, and simple three-dimensional shapes. Since it does not require a wax mold, the number of process steps is reduced.

In box casting, surface textures can be transferred to the glass by carving or applying patterns to the inner surface of the mold. Techniques such as shaping the surface before the plaster hardens (while it is still malleable) or applying stamps—similar to the stamping techniques used in ceramics—are also employed. The mold must undergo a three-stage preheating (predry) process (90°C → 230°C → 480°C), and a soaking period is required at each stage to ensure uniform temperature distribution within the kiln. Post-pour annealing is performed according to the Adams-Williamson rule, based on the maximum thickness of the piece. Since this method does not require handling wax, as in lost-wax casting, the number of process steps is reduced; however, the level of detail achievable is more limited than with the wax prototype technique.

Related Concepts

Kiln casting, lost-wax casting, preheated refractory plaster (predry) · Refractory plaster · Chikaoka-type refractory plaster · Adams-Williamson rule