Most of my pieces are fired at least twice. The first, a BISCUIT FIRING, to something approaching 1000 degrees centigrade, is usually needed to make the clay less fragile but still open, ready for glazing. Later there will be a further firing to a higher temperature, at which point the clay and the glaze will begin to fuse (vitrify).

GLAZES are suspensions of minerals in water, with different oxides added. I tend to improvise by pouring or unevenly sponging glazes , rather than spraying them. When a piece is dipped in glaze, it dries very quickly, leaving a whitish powdery surface which will than melt in the kiln at a high temperature (over 1200 centigrade) to produce a particular colour and texture.

Most of my larger pieces are REDUCTION FIRED in a gas kiln. What happens is that if you reduce the available oxygen in the atmosphere by slightly closing up the chimney vent towards the end of a firing, the combustion process will draw oxygen from the materials in the kiln, the clay and the glaze, which contain oxides. A spectacular green flame may appear out of the chimney vent during reduction. Reduction firing alters how glazes look and also brings the metallic content of the clay to the surface. This may produce an appealing toasted look, or even a metallic sheen or flecking of the clay . Unfortunately too much reduction may also blacken or muddy glazes.

SMOKE FIRING is an even less predictable process. The pieces are first biscuit-fired to make them less fragile, then packed in a dustbin full of sawdust, woodshavings and possibly other organic matter. The shavings are lit and smoulder for around 24 hours with the lid on top, but not tightly shut. How the pieces turn out depends on the wind, on chance, and on the nature of the material smoking in the bin. As an alternative, fast firings using newspaper can also produce interesting results.

RAKU FIRING can be quite theatrical. It involves opening up a kiln (often improvised) at around 1000 degrees centigrade and removing the pieces with tongs while still glowing red hot. You then bury them in a bed or bin of sawdust which smoulders, creating smoke which blackens any unglazed areas of clay. Thermal shock usually produces an overall crackle on the glazed areas.

NAKED RAKU is more complicated: a resist slip is used to prevent the glaze layer from adhering permanently to the surface of a burnished pot. After firing and smoking, the glaze is removed along with the resist slip, revealing a subtle patterning where the smoke has partially penetrated through the crackled glaze to the (naked) raku-fired clay surface.