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Published Jan 21, 2022

Slump molds are great tools in handbuilding because they allow you to dream up whatever shape you want and repeat it many times. They can be made from a wide variety of materials—from found objects to plaster.

Plywood is Joe Singewald's slump mold material of choice. In today's post, an excerpt from Making & Using Molds & Templates, he explains how he uses plywood to make his signature clover bowls. - Jennifer Poellot Harnetty, editor

Making a Paper Template 

My clover dishes are constructed with a slump-mold technique. Making the form requires basic woodworking tools and skills. The desired shape is first cut from a paper template to scale. Note: It’s important to know how much your clay shrinkage is so that you can compensate for it in the template. You can use any shape, symmetrical or asymmetrical, large as a serving platter or as small as a soap dish.

Cutting a Wood Slump Mold

With a marker, transfer the paper pattern onto a piece of plywood that is at least one inch larger than the paper pattern in all dimensions. Use a drill and jigsaw to cut out the pattern (figure 1). Start by drilling a hole just inside the traced form with a drill bit that is wider than the a jigsaw blade. Tip: Sometimes several holes make cutting complex forms easier. In this case, I cut three holes at each of the inner clover points. Next, slide the saw blade inside a drilled hole and slowly begin cutting along the pattern. Once the form has been cut and removed, hand sand the edge. Softening and slightly rounding this edge helps prevent unwanted shearing of the clay. Now your slump form is ready to be used.

Next, compress each side of the slab with a firm rib and then texture one side. I like to use self-made, bisque-fired, clay spindles or cords for texture (figure 2). The great thing about handbuilding with soft clay is how easy it is to impress while flat as opposed to impressing an already formed, leather hard, curved wall. Once textured, the clay is ready to be put in place. Drape the slab, texture side down, over the slump mold (figure 3). Lifting the clay-covered form from the tabletop immediately allows the clay to take shape. Tapping all four of the edges on a tabletop promotes further slumping (figure 4).

Now set the board and clay on wooden blocks or kiln posts tall enough so the draped clay does not touch the table surface. Wait the necessary time to allow the clay to become leather hard. I typically cover the slab with plastic and return the following day. The wooden form will absorb some of the clay’s moisture overnight. Once leather hard, the slumped slab can be removed from the mold and gently flipped onto a table. Next, cut a beveled edge, 1⁄8 of an inch from the outside edge (you will see a distinct line created from the wooden form) (figure 5). After placing foam on the mold (I re-use cone pack foam) return the clay to the form (figure 6). The foam prevents the clay from falling through after being cut.

Adding Walls to Form a Dish

Start by flattening coils of clay and cut them at equal widths. An extruder works great if you have access to one. I have made extruder dies from Masonite by cutting the wall cross section with a jigsaw in the same manner the clover mold was made. A string can be used to determine how long each of the three clover sides need to be. Next, attach the walls after slipping and scoring both parts (figure 7).

Cover the dish for a night, allowing the walls to become leather hard. Once this has occurred, add a worm-sized soft coil to fill in the inner seam where the walls connect to the base and where they connect to each other (figure 8). I often texture the exterior walls with a paddle or spindle tool. In this case, I used a Surform to true up the sides and to create texture. At the same time, I pinch and refine the lip.

Joe Singewald maintains a home and studio in River Falls, Wisconsin. Visit his website at