The firing process takes time and patience but it is worth the wait and still gives me a thrill to this day!
There are two firing processes. The first is called the biscuit firing. This reaches approx. 950C and the pots must be completely bone dry before the firing commences. I use the electric kilns for this and the firing takes about 8 hours to reach top temperature. The clay pots can touch / can be stacked in the biscuit firing.
The second firing is called the glaze (or glost) firing. In my case I favour using the gas kiln because I can create a ‘reduction’ atmosphere inside the firing chamber. I do this by starving the flame on the gas burners of oxygen. The flames ‘seeks out’ oxygen from wherever it can find it. Thus molecules of metal oxides present in the glazes and clay are stripped of oxygen and return to base metal. For example; copper oxide which in an electric (oxidising / neutral atmosphere) kiln will create a green glaze in the gas kiln with reduction will give a beautiful copper red glaze.
The glaze firing takes 10-11 hours to reach full temperature of over 1300C. I love the excitement of opening the kiln 36 hours later to see how the firing has gone. There are always some disappointments but also great surprises. It never ceases to give me a thrill.