Bisqueware Ceramics Definition | The Chemistry Lurking Behind

Bisqueware
Unfinished clay fish - after firing be a brown ceramic fish

 

What is bisqueware ceramics? Bisqueware is unfinished pottery that needs to be fired again before its in its final state. Bisqueware that has been fired in a kiln to a low temperature usually cone 04 or lower and is porous. At his stage it acts like a sponge. When dipped into a glaze it will absorb water and be coated with glaze. The longer you let the bisqued piece soak in the glaze, the more water it will absorb until the piece is finally saturated. Click here for more information on examples of ceramic materials.

What is the chemistry behind bisque?


Bisque is the first time that the clay is fired which is unlike unfired clay which has never been fired. Sometimes, the clay matures at a temperature higher than the glaze. If this is the case, the firing of bisque may be higher at temperature with the firing of a lower temperature glaze. As always the clay objects should be bone-dry before firing and should not be cold to the touch, indicating that they are not yet dry enough to fire. Occasionally, the bisque fire is called biscuit firing.

Can bisqueware be glazed or painted?


The bisque firing is in the low temperature range removes water and carbon from the clay and thus fuses the clay pieces together. At this stage, you can no longer add water to the clay and reform the piece. The shape of the clay now has a set shape. The end result is the clay piece is hard, but it is also porous and able to absorb a small amount of water from a glaze solution. What this does is allows the glaze to adhere to the clay. Once this has been done the clay piece is ready for firing. This will melt and fuse the glaze together with the clay. The intermediate stage of bisque is when it's intended to be glazed.

What is Porcelain Bisque?


White unglazed porcelain is known as porcelain bisque or bisque. It is common in European pottery because soft marble has a comparable appearance. It has a matte texture and surface.

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The bisque is now in it's final state


Looks a lot different now. Comparing the top image to this one the bisque is now in it's final state and look much better. The brown and red colors really pop and add visual interest to the ceramic wall decor. Firing in the kiln and adding a little glaze makes a big difference.

 

Bisque to Ceramic
The bisque fish was fired in the kiln - Final product

Comments

  1. If bisque porcelain is not finished, or complete, why is it so desired?

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  2. It is desired because the artist knows he or she has passed the first stage, the first firing. The first test if you will. And it is very important because many things can go wrong during the first firing. In my opinion, it is the most critical stage because the clay is still full of water and is very susceptible to breakage. Just to recap, Bisqueware is artwork that has been fired once in the kiln and thus has undergone a ceramic change. This a chemical change where clay becomes ceramic. And as you know can never be re-used or returned back to its former state of greenware. Bisqueware is still porous and therefore ready for glazing.

    Clay has a mind of its own and has to be persuaded to conform to the artist's shape. This technique is called compressing where the artist applies pressure to the clay achieving the desired results. But many times the clay fights back and does not conform to the shape. The result usually manifests during the first firing and the clay shows the artist who is boss by craking or braking. The artist has to know how far he or she can push the clay especially in vulnerable areas that are susceptible to cracking or problems. By applying pressure to the clay the artist causes the clay to be denser in that area.

    So, at this point, the artist is very happy that his or her artwork is still intact and ready for the next stage where more glaze can be applied and that's why it's most desirable. I hope that answers your question and thanks for asking.

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