Bisque refers to any pottery that has been fired in a kiln without a ceramic glaze. This can be a final product such as porcelain or unglazed earthenware or, most commonly, an intermediate stage in a glazed final product.
The porous nature of (fired) bisque earthenware means that it readily absorbs water, while vitreous wares such as porcelain, bone china and most stoneware are non-porous even without glazing. The temperature of bisque firing is today usually at least 1000°C, although higher temperatures are common. The firing of the ware that results in the bisque article causes permanent chemical and physical changes to occur. These result in a much harder and more resilient article which can still be porous, and this can ease the application of glazes.
In situations where two firings are used, the first firing is called the bisque firing, and the second firing is called the glaze firing.
