How To Make Clay Slabs For Hand Building Pottery

This is where problems can develop. The grain in a slab will affect the clay’s shrinkage. The slab will shrink more along the width, across the grain, than it will along its length, or with the grain. If pieces are assembled so that the grains aren’t aligned in the same direction, the pot can pull itself apart during drying and firing. To flip a large slab, you will need two pieces of canvas, larger than the slab will be. Begin by rolling the slab on one piece of canvas. After the initial rolling, cover the slab with the second piece of canvas. Spreading out your hands as much as possible to support the clay, flip the canvas-clay-canvas sandwich over. Remove the top layer of the canvas (that used to be the bottom) and continue rolling. If you want to be certain that a slab is uniform in thickness, you can use two slats of wood on either side of the slab as depth guides. Just be sure to rotate the slab as you roll, rather like rolling out pie dough. Use plastic wrap instead of canvas. Flatten the clay between your palms, then lay it between two sheets of plastic wrap. Roll with a rolling pin, being careful that no wrinkles develop in the plastic. Rotate and roll out again, repeating this sequence until the clay is as thin as you desire. Carefully pull the uppermost piece of wrap straight back and away from the clay. After firmly applying the thin slab to the other clay surface, pull the second piece of wrap straight back and away. The clay slab should stick to the other clay surface. To do this, add a couple of handfuls of chopped nylon per hundred pounds dry weight to the clay as you mix it. Sprinkle the nylon in while the dry clay is combining in the clay mixer, before adding the water. You may also be able to special order a custom mixed batch of clay; check with your favorite supplier. When using a slab roller, care must be taken to avoid creating a grain in the clay. If the slab is too long to fit width-wise in the roller when rotated, roll across the width of the slab with a rolling pin using very positive, even aggressive, strokes.