Drying the Ceramic
A Ceramic kiln helps remove all of the water from ceramic wares prior to firing or during the firing process. Ceramic contains crystal bound water that cannot simply evaporate and a kiln is used at low temperatures to dry out the ceramic. This process is know as a "bisque" or a "single" firing and the resulting ceramic is chemically different and ready for complete firing at higher temperatures.
Firing the Ceramic
When the kiln is used for a full firing of ceramic, the high temperatures of the kiln change the actual particles of the ceramic from clay into finished ceramic. First, a process called burnout begins in which the ceramic is heated to the point at which all impurities are burned away. Second, a process called sintering happens, which means that the particles of ceramic bond to each other and the ware becomes waterproof and structurally stronger. Finally, and at higher temperatures, decomposition occurs , where the basic oxide particles of the ceramic are broken down.
Glazing the Ceramic
The final stages of making ceramic using a kiln involve glazing the ware in order to seal it and give it a finished look. This involves a process called vitrification in which the ceramic ware is heated to such high temperatures that the oxidation of the exposed ceramic increases so high that the quartz crystal structures with the ceramic actually melt and flow together giving the finished glazed ceramic product its shiny polished look.
