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Making Simple Molds for Slabware
Posted By Jonathan Kaplan On July 26, 2013 @ 9:14 am In Daily,Features,Handbuilding Techniques | 8 Comments
My son starts kindergarten this year (how could that possibly be?!), so the rapid pace at which this summer is flying by is on my mind quite a bit. This might also be the case for all of those school teachers out there.
So, today I thought I’d share a project that would work great as a lesson plan from a technique in Pottery Making Illustrated. It would also work great for all of you non teachers who are just looking for new ways to streamline your processes in the studio. - Jennifer Harnetty, editor.
What you will need:
1 inch blue Styrofoam, available at home centers in 4×8 ft. sheets (one sheet can make many molds)
Straightedge or ruler
Jigsaw with an adjustable base plate.
Learn to teach handbuilding!
Neil Patterson has spent years putting on workshops to help art teachers introduce clay into their curriculums. In his comprehensive video, Neil provides all the information you need to begin teaching handbuilding techniques – pinch, coil, and slab – to anyone, young or old. And if you’ve never tried it, you’ll find this video a great place to start.
The first step is to make a template for the shape you wish to make in clay. This can be an oval, a square, a rectangle, or any other polygon shape. Draw an oval on a piece of matte board, Masonite, or thin plywood.
Then extend a rectangle around its perimeter as shown in figure 1. This will give the template some rigidity. Make sure to oversize the mold to account for the shrinkage of your clay body. Lay the template on the Styrofoam sheet. Measure an additional 1 inch around the perimeter of the template to make the mold sturdy and rigid and, using a felt-tipped marker, draw the perimeter of the template as well as the inside shape (figure 1).
Then, using a sharp utility knife and a ruler, cut the Styrofoam along the outside perimeter. Once this basic shape is finished, it’s time to cut the interior shape, which will then be used to form the inside of the oval platter. Using a jigsaw set at a 20° angle cut out the oval (figure 2). Remember that the saw blade needs to bevel the oval outward, so that the top of the cut is wider than the bottom. This is called ‘draft’ and allows for the easy removal of the pressed clay piece.
Remove the cut oval (figure 3) and using a piece of medium-grit sandpaper, sand the cut edge smooth (figure 4). Then place this cut piece on a larger piece of Styrofoam and cut a rectangle to correspond to the outside edge of the first mold piece. This becomes the bottom of the mold. Once cut and squared up, use duct tape along all the edges and the face to secure the bottom of the mold to the top piece with the cut oval (figure 5). Your mold is now complete! If you wish to make different shapes, now is a great time to make additional molds so that you have a variety of shapes to work with.
Making an Oval Plate
Using a slab roller or a rolling pin, roll out a slab. Macy uses a selection of SlabMats with a table top slab roller for smaller pieces. Canvas can also be used as an alternative to the SlabMats. The slab is rolled with a SlabMat on the top and the bottom of the clay. This allows the finished slab to be moved without distortion. Macy uses the outside perimeter of the Styrofoam mold to estimate an approximate size to cut the slab.
Once the slab is prepared, he uses a small rib, moving in all directions to smooth out any marks in the slab and to compress the surface. Remember that the slab is just slightly thicker than what is desired for the finished ware since it will become thinner once it’s worked into the mold. Removing the top SlabMat, the mold is positioned upside down over the freshly rolled slab. The SlabMat is then wrapped over the mold and the entire “sandwich” is flipped over in one smooth move. The mat is removed revealing the slab as it begins to slump and conform to the cut Styrofoam oval.
After the piece has set up, it can be safely removed from the mold by gently but swiftly flipping it onto a ware board (figure 9). Lastly, the piece is flipped over, the outside edge can be detailed and smoothed with a sponge or rib. To make sure the bottom does not dome up during the drying, he presses the bottom of the platter so that it stays flat.
Macy Dorf, a well-established potter in Denver, Colorado, makes a colorful line of high-fired functional stoneware. He sells work out of his storefront in the Santa Fe Arts District as well as to galleries and craft shops in many western states. Jonathan Kaplan is a potter, designer, and gallerist living in Denver, Colorado.
For more handbuilding inspiration, be sure to download your free copy of
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