Ceramics is an art that uses both form and function. The potter must master basic construction techniques to create successful pottery. Beyond function, the artist can also use carving and sculptural techniques, as well as glazing and firing techniques, to give each piece a unique feel.
To prepare, the potter must wedge or knead the clay on a canvas board to achieve a homogeneous moisture level throughout the clay. Once the clay is homogeneous, the potter can start constructing a vessel. Slab construction consists of rolling out slabs of clay, cutting shapes from those slabs and then attaching those shapes to make a form. When attaching clay, score or cut shallow slits into the areas being attached. Then paint a layer of slip, which is clay in liquid form, on the two areas and carefully push them together. The slip acts like glue, holding the joint in place. The potter can also construct a vessel on the wheel. To do this, the potter places a ball of clay on the wheel and wets it down. Then the artist starts the wheel and centers the clay by slightly pushing one side into the middle. The potter can open a mouth for the pot by pushing a finger into the middle of the clay. That hole can then be pulled slowly to one side to widen the pot. To create the walls, the artist pulls the clay up on one side. The potter can alter hand movement to create different forms. The pot can be finished off with a metal scraper to remove any finger marks and then cut from the wheel using a wire cutter.
Carving and Sculptural Techniques
Ceramicists can use carving tools to create patterns and images in the clay. This process is done when the clay is in a leather-hard stage, which is the stage during which it will retain shape but will carve easily without producing dust. Artists can also attach sculptural additions to pots by scoring both the pot and the clay piece, painting on slip and then carefully attaching pieces to the vessel. Artists can also use slip bottles, which have fine applicator tips, to draw raised images on the pots.
Glazing and Firing Techniques
Glazes are comprised of minerals in water and are designed to fuse in the kiln to create a water-proof surface. Potters can use a variety of glaze colors and even combine glazes to get different effects. It is important to test fire glazes because they will change color when fired. Potters can also draw or paint images on bisque-fired pots using underglazes. The underglazes, which come in a variety of colors, are meant to be used underneath a clear glaze. Color and effects can also be achieved through the firing process. Both salt and ash firings introduce substances during the firing process that organically and unpredictably change the surface of the clay. A raku finish involves removing the clay during firing and immersing it in wood chips to help pull carbon to the surface. This creates a charred and sometimes sparkling effect.