Eileen Nisbet: Ceramic Sculpture - Methods and Techniques.

Slabs of David Leach Prepared Porcelain Body, (Grolleg ECC 52,FFF Feldspar 25, Quartz (200 mesh) 18, Bentonite 5) which is a semi-porcelain, were rolled out on thin polythene of the kind that covers dry cleaned clothes. This allowed the slabs to be moved and turned without breakage until evenly dry. The shapes were cut out with a pointed palette knife and left to dry until almost leather hard. At this stage, holes could be drilled into the clay, leaving circular protuberances on the underside. When the clay became leather hard, the edges could be tapered, smoothed or roughened with a metal kidney or shim.

For small painted areas, casting slip and body stain were mixed and the consistency balanced for a good flow. The mixture could then be painted on to almost dry porcelain. Two thin coats ensured that the colour was even and the surface was then further improved by light burnishing. Lines for inlaid colours were scratched into the surface of the clay with a pointed palette knife. Dry clay gives a crisp line, whereas a wetish clay gives a jagged quality. Inlay colours composed of body stains used without adding clay, were laid into the scratched lines with a brush, left to dry and then scraped back with a shim. Oxides were often added to increase the variety of colour.

Finished slabs were placed directly onto kiln shelves kept smooth and clean by rubbing with a carborundum stone. To prevent warping, they were fired once and extremely slowly, in a 60 x 60 x 68 cm electric kiln. A gradual build up of temperature, overnight on a low setting, was followed by a medium and then a high setting lasting no longer than 1 hour, reaching a final temperature of 1240°C. On later works, low temperature ceramic enamels were applied with a brush and the slabs returned to the kiln to be fired at 770°C.

The fired slabs were then assembled flat on the work table. After careful consideration for the positioning of each element within the sculpture, partial outlines were drawn on the table to accurately define their relative placement. The placement was often double-checked by looking at the arrangement in a mirror. A square wooden block was then clamped to the front edge of the table and the elements were then layered alternately with tubular porcelain spacers, keeping the base elements in contact with the block. Epoxy resin adhesive similar to that used for ceramic renovation was used to fix the assembly.

.