Penny Decker doing a slip cast : Photo : Cosanti Foundation

The process continues when we fill these plaster molds with our slip mixture. Immediately the plaster acts like a sponge drawing out the water molecules from the slip. The clay molecules are too large to pass through the plaster so they get deposited along the inside walls of the plaster molds. As this process continues a clay shell begins to form inside the mold which increases over time. When the ceramicist decides that the thickness of the shell is correct for that particular style, a suction device is used to extract the remaining liquid slip from the center of the mold leaving the shell behind. This shell is the bell or pot in its early stage of production.

As the product is exposed to more air and sun it will continue to lose moisture. Soon it will begin to shrink away from the edges of its mold. At this stage the piece is removed from its mold. Next a colored clay powder is applied to its surface, covering the natural color of the clay. We do this so that when we carve designs into the clay body, a color contrast is set up between the carved designs which which reveals the actual color of the clay and the applied color of the rest of the piece. Our designs are hand carved, one-of-a-kind, performed when the clay body is leather-hard. We use a specially designed and modified utility knife blade created by Paolo Soleri. In order to keep within the Soleri style of design, our work is generally abstract or geometrical. We strive for simplicity and elegance. Periodically, Paolo reviews our carvings to assist us in maintaining the Cosanti Originals standard of design.

When we accumulate approximately 250 pieces, we fire the bells in an updraft propane kiln to a temperature of about 2100 F . When the bells and pots are removed from the kiln, they are assembled with clappers, chains and clappers and are ready for distribution.The second way we have of making bells is with the use of silt as our mold medium. Silt is a very fine sand, almost like powder, which gets deposited naturally along river banks and in river beds. One of the qualities of silt is its ability to retain any shape it is pressed into while it is moist. Every couple of years we go down to our river to collect a supply.

Silt Casting