Ceramic Process: Firing

Ceramic Process: Firing

Here’s a basic explanation of the firing process of ceramics, enough to understand in a more comprehensive way what happens when clay is exposed to high firing temperatures. 

Today we will be describing the different firings that clay is exposed to. It is essential to consider that clay undergoes major changes  in each firing. There are important transformations in the clay particles and their interaction with glaze materials when exposed to firing temperatures.  

In a few words, what the firing does is turn raw clay into ceramic.

We call greenware to clay that hasn’t been fired yet (raw clay). When a clay pot has dried completely and all water has evaporated, it is ready to be exposed to a first firing, done at 1000℃, called bisque firing. Here is where clay matures to the point where it will not dissolve nor go back to its wet state if submerged in water. 

After bisque firing comes glaze firing. There are different glaze firing temperatures, depending on the type of clay, the firing method, and the type of glazes that are being used. During this firing, clay and glazes vitrify. All glaze fires reach a temperature above 1000℃, but still earthenware, stoneware, and porcelain clays are meant to each reach a different temperature.

Some of the firing methods potters use are wood firing (pit firing and wood-fired kilns), reduction firing (gas kilns), raku (also considered a reduction firing), and oxidation firing (electric kilns). 

Stay tuned until our next post of this series on ‘Ceramic Process’, where we will explain each of these firing methods in more detail. 

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