Slip casting a Large Bowl
IN THE STUDIO
The creative process
I do all my own work—from creating and developing the forms, to making the molds, preparing the clay and casting the pieces. The prototypes are made by the coil method, not thrown. I love the asymmetrical effect that develops with hand-building the clay. I do a great deal of work on the piece after it is cast and removed from the mold. From there on it becomes a blank canvas! Surfaces are drawn on and carefully carved out with a small knife to create a a subtle 'negative' design with areas that have been opened up. The carved edges also allows the gold to catch and reflect the light.
The final surface colours are achieved by the application of stains and oxides on the unfired clay, using up to five different colours to get the desired effect. The pieces are then low-fired in what is called the bisque firing, The bisqued pieces are then glazed and re-fired in the kiln at much higher temperatures. By the end, pieces have been put through at least four firings to find the depth of colour and that 'just right' textural feel.
Creative and colour development usually takes up to a year to evolve. In particular I'm looking for the startling contrast of the soft, matte-suede feel of the bare, colourfully fired clay surfaces against the high-gloss glazes, the opalescent Mother of Pearl luster and the fired gold. The gold is not a glaze but rather, pure 22-k gold, suspended in a solution formulated to mature in the firing process. The binding solution burns away leaving the gold permanently adhered to the surface.
Starting a new piece — a Large Gallery Bowl (shown at left)
Slip casting and press molding are very useful processes in clay. For me the slip cast process creates a blank canvas that I can work on, draw on and carve away on, or add any number of other decorative choices to make each piece unique and interesting. Here I am pouring the clay slip into the plaster mold for the 18 inch Gallery Bowl. It takes about 50 lbs. of clay and several pours to fill this one mold.
After about an hour and a half, the plaster has absorbed enough of the water from the clay, leaving a layer of thicker clay along the surface of the mold. The longer I leave the clay without emptying it, the thicker the bowl will be. After emptying the mold, it needs to be propped up vertically for an hour or so until all the wet clay has drained out.
After drying for a few days, depending on humidity, the cast clay is stiff enough to be taken out of the mold. It will then need to dry a bit more until it is stiff enough to be handled easily. All the rough wobbly parts are then scraped away until smooth and the rim of the bowl resolved.
The bottom image shows me applying the Mother of Pearl and green lusters prior to the third firing.