Wedging is a technique for preparing clay for working. Clay that has not been wedged will have an uneven texture, making it difficult to work with and potentially causing problems as it is worked and fired. In some cases, unwedged clay will explode in the kiln, destroying many of the pieces that are fired with the clay. This can enrage people whose work was ruined as a result of the explosion in the case of shared kilns.
Wedging is a method of removing hard spots in clay repeatedly kneading it on a porous surface to draw some of the water out while evenly distributing the moisture. Air bubbles are forced out of the clay during the process, ensuring that they do not heat up and cause the clay to explode in the kiln. Clay that has been properly wedged is very smooth and even in texture, making it easy and enjoyable to work with. People can also use clay to set it up for specific tasks while wedgeing, such as a conical wedge of clay that is ideal for working on the wheel.
Wedging can also be used to blend multiple types of clay together, ensuring that the clay is thoroughly and evenly worked and that no patches or pockets of one type of clay remain. Potters who use recycled or reclaimed clay often take extra precautions with their wedging to ensure that the clay has been properly prepared.
It’s crucial to create a conducive environment for wedging. A counter or block should be used to work with the clay, and it should be at a comfortable height for kneading. Tables work well for this, though people who are unusually tall or short may need to find a more adjustable surface to wedge without straining their arms, shoulders, or backs. A wedging table in a pottery studio might have a slab of basalt, concrete, or another porous material on which clay can be worked directly, but a canvas sheet can also be used for wedging.
The goal is to knead and work the clay into a smooth mass, but everyone wedges differently. Some people prefer to slam the clay during the wedging process, while others prefer to use their hands to create a churning motion that keeps the clay rotating in order to press the air bubbles out. People who bake bread often knead clay in the same way they knead dough. Some people use a technique called wire wedging, in which the clay is cut, stacked, and slammed against the table several times to thoroughly blend it.
People who are new to wedge clay may want to start wedgeing two different colored pieces of clay together. The mixture of colors will serve as a visual indicator of their progress, allowing for frequent checks on the wedging process. People can work with a single color of wedged clay once they’ve gotten used to the texture and feel of it.