Maintaining Integrity Dan Ingersoll

Appears in the May/Jun 2019 issue of Pottery Making Illustrated.

From my perspective, a creative approach to process in ceramics isn’t about coming up with a method of work that is totally new; rather, it lies in combining existing processes in new ways. Over time, I have developed a method for creating larger slab forms that combines the use of soft clay slabs, cut and folded paper patterns and mock-ups, a cast plaster support form, and plastic food wrap.

Using cut and folded paper to generate ideas for clay forms was the result of two experiences. The first was the building of a stressed-plywood sailboat that employed thin, flat plywood and V-shaped cutouts, which, when drawn together, created a three-dimensional boat form. The second was a workshop I took from Randy Johnston, in which he encouraged the use of cut and folded paper to explore ideas for ceramic forms. Later, when visiting his studio, I observed that he used wooden forms to support his large, boat-like platters during construction. I co-opted this idea of a wooden support system into a plaster support, cast directly from a paper pattern.

Plan at Hand

Begin with paper, scissors, tape, and a mindset of exploration. Explore cutting slits and darts, folding, and taping paper together to generate as many different three-dimensional forms as you can (1, 2).

With a paper design in hand, the next step is to create a plaster cast directly from the paper form. Scale the paper design to actual size and cut it out of heavy tag board (you will need a second full-sized pattern later in the process, so make two). Before cutting, while the tag board is still flat, reinforce the back with continuous strips of packing tape to strengthen and waterproof the form, giving it the integrity needed to support the wet plaster when poured. Cut out and assemble the pattern with additional tape. This paper and packing-tape form then becomes a mold pattern. If your paper pattern doesn’t have a straight and level top edge, add additional pieces of paper and tape to the form to create a flat edge that will contain the wet plaster. The packing-taped paper mold pattern is then placed in a cardboard box that has been resized to fit the form. With damp playground sand, fill the void between the pattern and the box to support the weight of the plaster and prevent the paper pattern from distorting when the mold is filled (3). Note: When filling the voids around the packing-taped paper pattern, simultaneously add sand to the interior of the pattern to equalize the force of the weight of the sand on it.

When both are filled to the top of the box, gently press down on the sand in the interior of the form. This packs the damp sand on the exterior and causes it to stay in place. After doing this, scoop the sand from the interior with a utensil, then vacuum up any remaining sand. Spraying the tag-board pattern with vegetable oil prevents the paper from sticking to the set plaster. Mix #1 Pottery Plaster according to directions then pour the mixture into the mold (4). Remove the plaster form from the mold when it’s set and let it dry out completely before using (5).

Creating the Clay Form

To create the final clay form, roll out a slab large enough to fit your pattern. Before rolling it to its final thickness, place the clay onto a sheet of plastic wrap laid flat on your table. Use the second paper pattern to trace onto the soft clay slab and cut it out, using care not to cut through the plastic wrap under the slab (6). Remove all excess clay from the cut-out slab. Leaving excess plastic at the ends of the slab allows it to be wrapped around sticks that serve as handles to pick up the slab. This plastic wrap support allows the slab to be transferred to the plaster mold without being distorted (7).

When the slab is in place, the plastic wrap is pulled away from the clay and smoothed against the mold at any point where a seam is made so as not to interfere with the joint. The plastic is not removed and remains as a layer between the clay and the mold. Note: As the clay stiffens and shrinks on the support form, the plastic allows the clay to move freely without sticking to the plaster. This layer of plastic prevents the plaster from drawing moisture out of the clay. However, I haven’t found this to be an issue.

To join the seams when using very soft clay it’s not necessary to slip and score. If your clay is leather hard, then score the edges and add slip before joining seams. After the clay slab has been placed on the support, the joints are drawn up, butted together (rather than overlapped), and forced in a V shape (8). Then, using what I call seaming blocks (two 3×4×1/2-inch-thick blocks of wood with rounded edges), the V between the edges to be joined is closed and compressed by squeezing them together with the blocks (9). The blocks are placed on the clay about a half an inch out from the joint. Then using firm pressure, the blocks are pressed down to bite into the clay and then pressed together to create a strong, compressed joint.

When the clay is leather hard and able to support its own weight, remove the form from the plaster support. Remove the plastic and smooth all interior seams by adding slip, scoring the seam, and attaching and blending a coil.

Refine the Form

Finally, refine and clean up the form as desired (10). Once the interior seams have been reinforced, the protruding exterior seams may be removed with a Surform or integrated into the final design.

In the end, there are many ways to accomplish a task. Using paper patterns and mock-ups allows for simple, yet deep, exploration of form and proportion. Support systems for soft-slab work can be made of wood, Styrofoam, found objects, and so on; however, I like the direct reflection of the original idea from a cast plaster support. While they become more things in the studio that need a home, I find that they are durable fodder for new ideas, and I love exploring their potential for creating new forms that are different from the original ideas.

All finished pieces shown above were constructed using elements created with the plaster form shown previously in this article.

Dan Ingersoll taught K–12 art in the public school system for 30 years (17 of them teaching high-school ceramics). Following retirement, for three years, he was a lecturer in art education at the University of Wisconsin, Eau Claire. He is currently retired and pursuing his passion for clay in a small basement studio and wood firing with a fellow potter. His work has been shown on both a regional and national level.