First I decide how the piece will be mounted, which impacts the design. I will either use a plaster hump mold or hand build the clay. Use of rails provide a even thickness of the clay. I have found this impacts both the firing and the final look of the product.

Once you have completed making your clay or wax models secure it to a melamine board. Center the model in the middle of that board. Make sure you have a large enough board around your model to accommodate the 2-3 inch gap plus the coddles then space to secure the outside of the coddle to prevent leaks. The larger your piece becomes the more the mold needs to be thicker and you increase the depth and the size of the coddles proportional to the size of the model.

Using quick grips or C-clamps and I pinwheel them around the piece. Use snakes of clay to secure the inside walls around the base and up the wall. Then 1-2 inch thick snakes on the outside of the coddle at the base to insure the plaster does not leak out. If you use a 2″ mold thickness then mark the highest portion of the model and add 2-2.5 inches, mark with a pencil to give you a visual pour level reference and to keep the mold uniform in size for firing purposes. 3″ molds you add 3 inches, etc.

Then prepare your plaster silica mix for the face coat and a plaster silica additive as your back up coat. Pour into the corner of the coddle allowing the plaster to raise to the reference line. Gently shake without moving the clay to remove any excess bubbles then let sit for 40 minutes. This step use great caution to prevent blow outs of plaster from your coddle.