Bisque (noun) in pottery refers to ware which 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. It is also sometimes called biscuit or bisc.
Bisqueware: This is a synonym. It refers to pots that have been bisqued (fired for the first time). It may also be called biscuit ware.
To bisque (verb) is to fire the clay for the first time.
Bisque fire (noun) 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 of Bisque in Pottery Terms
- It is time to load the bisque in for its glaze firing. (noun -- short for "bisqueware")
- 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)
The Chemistry of Bisque
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 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
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, and other purposes where it contacts liquid as it is porous. You need to glaze it to use it in those ways. If a luster is placed, it is not food safe. Bisque intended only to be ornamental may be painted with acrylic paint and not fired. In this case, it would not generally be in contact with liquid, and should be kept dry.
Unglazed white porcelain is called bisque porcelain or bisque. It is popular in European pottery as it has a similar appearance to smooth marble. It has a matte surface and texture. It was popular for the making of bisque dolls and figurines.