Bisque refers to ware that has been fired once and has no chemically bonded water left in the clay. Bisque is a true ceramic material, although the clay body has not yet reached maturity. This stage is also sometimes called biscuit or bisc. Bisqueware is the term for pots that have been bisqued—fired for the first time. The pots may also be called biscuit ware. To bisque is to fire the clay for the first time. Bisque fire is the first firing and is usually only to between cones 08 and 06—1720 and 1835 degrees F or 945 and 1005 degrees C. However, sometimes a clay matures at a higher temperature than the glaze that the potter wants to use on the pot. When that is the case, the bisque firing may be higher in temperature with a lower temperature glaze firing. Before firing, the objects should be bone dry and should not be cold to the touch, which would indicate they are still not dry enough to fire. The bisque fire is sometimes called biscuit firing.
Examples
It is time to load the bisque in for its glaze firing. (noun)Bisqued pots are often rather pink in color. (adjective)When will you bisque the pots you threw last week? (verb)These pots are bone dry and ready for their bisque firing. (adjective)
Chemistry
The bisque firing is in the low-fire range. It drives off the water and carbon from the clay and fuses the clay particles together. From this stage, you can no longer add water to the clay and reform the object, it now has a set shape. The resulting piece is hard, but it is also porous and able to absorb a small amount of water from the glaze solution. This allows the glaze to adhere to the piece to be ready for firing to melt and fuse the glaze. When a bisque object is intended to be glazed, the bisque stage is an intermediate stage.
Glazing or Painting
Bisque can be painted with ceramic glazes or underglazes and then fired, after which it is water safe. Depending on the glaze, it may be food safe. You can’t use unglazed bisque for food, drink, vases or other purposes where it contacts liquid because it is porous. You need to glaze bisque to use it in those ways. If a luster is placed, it is not food safe. Bisque that is intended only to be ornamental may be painted with acrylic paint and not fired. In this case, it does not generally come in contact with liquid, and it should be kept dry.
Bisque Porcelain
Unglazed white porcelain is called bisque porcelain or bisque. It is popular in European pottery because it has a similar appearance to smooth marble. It has a matte surface and texture. It was once popular for the making of bisque dolls and figurines.
