There are lots of ways to make clay molds, as you'll see in our free download Ceramic Mold Making Techniques. And I love that I keep discovering new variations on these mold making techniques.
Case in point: Nancy Zoller's textured bisque hump molds. I love how Nancy incorporates texture right into the clay mold, and adds a spiral detail to make a piece look thrown. In today's post, Nancy explains her straightforward process for making textured hump molds for clay.
-Jennifer Harnetty, editor.
Simple Textured Hump Molds for Ceramics
by Nancy Zoller
Making the Bisque Hump Mold
Once you've found or made a drape form, you've ready to start making your bisque mold on top of it. Roll out a slab of clay about 1/4 inch thick and place it over your drape mold (figure 1). If your drape form is glass or metal, place a piece of plastic wrap between the form and the clay to keep the slab from sticking. Cut and smooth the bottom edge so that it's a straight, even and level line, following the base of the form.
Stamp into the clay surface as if you were making a piece with a concave, design (figure 2). Make your own clay stamps or use items from nature such as shells, pine cones, and leaves. Using a wheel and a ribbon or loop tool, carve borders or defining lines to frame in your design. Remember that whatever is carved into the clay will be raised and reversed in your future piece.
If your hump mold is round, place it on the wheel, center it and secure it with lugs of clay as you would when trimming and use a metal rib to create a spiral in the middle giving it a thrown appearance if you wish. Usually, a small leaf finds its way into the interior of the design on my work (figure 3). Once you've finished the design work, wait until the piece is leather hard and remove it from the mold. Let the form dry slowly, then bisque fire it.
Final Convex Piece
Roll out a slab of clay and place it over the bisqued clay mold (figure 4). With a small hand roller firmly roll the clay from the center of the mold out toward the edge (figure 5). Use a rubber rib to smooth this surface after rolling. Cut and smooth the bottom edge with a needle tool following the base of the mold.
At this point, you can extrude a 1/2 inch thick coil to add a raised foot to the form. The clay and the coil need to be the same wetness. If the form is round, place the mold on the wheel, center it, and secure it with clay lugs, and throw the foot. Using your pin tool, make two concentric circles about a half inch apart while the wheel is spinning to indicate where you will place the coil. Place the coil (figure 6), then press downward on the inside and outside of it to adhere it to the base surface. Once it's fastened, firmly give the coil an upward pull to create height, then smooth the surface with a chamois or sponge (figure 7).
To add the coil to an oval, square or oblong form, simply eyeball where you want it. Lay the coil down and be sure to bevel the edges where they join to secure the connection. Use a flat wooden tool to smooth the coil on the inside creating a secure join. When the coil is secured, smooth the transition between the coil and pot with a rubber rib (figure 8). Use similar clay stamps on the outside of the foot to tie the patterns together (figure 9).
For more interesting ceramic decorating techniques, download your free copy of Five Great Pottery Decorating Techniques: A How-to Guide for Decorating Ceramics with Slip Transfers, Chinese Brush Techniques, Ceramic Slip, Sgraffito, and More.