Kiln Firing FAQ - FAQs

New elements fired to around 1100°C in an empty kiln will develop the oxide layer on the surface of the wire more quickly and should improve element life. If the glaze or clay being used produces aggressive fumes such as fluorine then this is worth doing, with usual materials the benefit is marginal.

If the door is opened when the kiln is above 200°C there is a risk of cracking the pottery because of uneven cooling at the critical point of sudden contraction. 

Moving or bending an element can result in it snapping as they become very brittle with firing. First heat the element to red heat with a blow lamp and then bend to shape with long nosed pliers. Staples made of element wire might be helpful to hold it more securely.

New designs, materials and methods of construction are minimising this problem however some cracking may occur because of expansion/contraction stresses. Opening the kiln too early will increase the risk of bricks cracking. As long as they are not structural even severe cracking will not affect the firing performance.

The first firing, (bisque or biscuit) should be quite slow to avoid moisture trapped in the clay from turning to steam which will shatter the ware The best approach is to fire   50degC-100degC  per hour up to 600degC then 150deg per hour up to 1000degC For glazing  150degC per hour  500 degC then 250degC  up to maturing temperature of glaze