This article describes techniques for the construction of clay sculpture that is intended to be fired.
1. Decide how you want to create your sculpture. Sculpture can be created by piecing together things thrown on the wheel, by the use of coils and slabs, by making solid objects out of clay, or any combination thereof. Of course one can also use molds, a subject in itself.
2. Hollow out your sculpture. Clay cannot be fired solid, and should only be usually no more than a half inch thick in any place. You can use ceramic trimming tools to scrape and dig out the clay while still retaining a strong wall.
3. Keep your creation uniform to prevent shrinkage and cracking. Different thickness of clay will shrink at different rates, so most parts of a single piece should be of roughly the same thickness.
4. Use plastic sheets and bags are to keep the work wet while building, and to control drying speed. Water can be added at any time with various size sponges. Red iron clay tends to dry slower, have a lot of strength, and is very workable.
5. Reassemble the piece by scoring both ends of reattached pieces and using adhesive mud. Reused clay soaked in water can be used as adhesive for attaching parts. Dried clay soaked and dissolved in water works best. Put in, say a wide-mouth gallon size plastic jar and let water evaporate and clay congeal to a thick axel grease consistency. This may take a few weeks. This adhesive clay is applied to both ends after scoring and pressed together. With a wooden tool the edges are mashed together both inside and out. Then covered with stiff working clay for strength. When the piece is reassembled all exterior joints are contoured for the final finish. This is then dried slowly, the bigger and thicker pieces the longer taking up to two or three weeks. If the hollowed walls are done unevenly, with curved trimming tools leaving lots of ribbing, pieces will not warp like as will smooth slabs.
6. Roll out coils with fingers, usually starting from the center and working both hands away from each other. When joining coils lengthwise for pots, they can be scored and adhesive clay applied or not. However, usually the inside should be mashed together for strength. Coils are especially vulnerable to separation on the bottom.
7. Roll out slabs with a rolling pin. For even rolling, place two strips of material like wood, the thickness of the intended slab, such that the ends of the rolling pin when rolled on the strips have flattened the clay to that exact width. Slabs will tend to considerable warp in the fire. Interior ceramic bracing may be necessary to mute this. Plaster used as a working surface will tend to dry out the clay. Find a non-stick surface such as raw wood.
8. Create texture in innumerable ways such as rolling clay on burlap, branding with all sorts of implements, carving, using imprint tools.
9. Finish the piece. Ceramic sculpture can be glazed, stains painted, or it can be fired and then painted with acrylics or oils or any combination thereof. Sculpture too big for the kiln can made in pieces to be fitted together after firing. Allowance must be made for attachment in the interior and the ability to cover and color the cracks so they do not show. Ceramic sculpture is delicate and subject to breakage.