Bisquefiring

Bisquefiring, also called biscuit firing, is the first firing of pottery after the pieces have been shaped and thoroughly dried. The goal is to convert the dried clay into a durable ceramic state by driving off chemically bound water and any organic residues. Bisqued ware becomes structurally stable enough to handle without rehydrating, and it becomes porous enough to accept glaze later.

Process and temperatures: The firing is carried out in a kiln—electric, gas, or wood-fired—with a controlled, gradual ramp to a low-to-mid-fire temperature. The target is typically in the low-fire to mid-fire range, commonly described as cone 04–06, approximately 1000–1050 °C. A soak may be held at the peak temperature to ensure moisture removal and material transformation, followed by slow cooling to minimize cracking and thermal shock.

Outcomes and uses: Bisque ware is hard but still porous and not water-tight. It is often cleaned of surface dust and debris before glazing. Because the surface is more receptive to glaze, glazes applied to bisque-fired pieces fuse in a second firing at higher temperatures. Bisqued ware is ready for glazing and subsequent glaze firing, which bonds the glaze to the surface.

Variations and notes: The exact temperature and soak time depend on the clay body, kiln type, and desired results. Some clays or techniques, such as porcelain or stoneware, may require higher bisque temperatures. Bisquefiring is a standard step in most ceramic production and hobby practice and is distinct from glaze firing, which occurs after glazing.