Ceramics, the focus of this part of our web guide, refers to the craft of making pottery and other objects from clay and decorating them.

Ceramics refers to objects created by shaping clay and other raw materials, then firing them at high temperatures. This thermal process alters the molecular structure of the clay, producing a hard, stable material that resists heat and chemicals. Glazing is often applied before a second firing. A glaze is a glassy coating that seals the surface, adds color, and increases durability. Combined forming and glazing allow for a wide range of textures, finishes, and decorative effects.

The major categories of pottery are defined by different firing temperatures and clay bodies.

Earthenware: Fired at lower temperatures, around 1,832 to 2,102°F, earthenware remains porous unless glazed. Examples include sigillata and delftware.

Stoneware: Fired between 2,192 to 2,372°F, stoneware is vitrified and nonporous. It ranges from rustic brownware to translucent porcelain-like bodies.

Porcelain: Made from refined kaolin clay and fired above 1,300°F, porcelain is prized for its whiteness, strength, and translucency.

Terracotta: An unglazed earthenware, terracotta is recognized by its reddish color and rough texture. It is often used for architectural elements and gardenware.

Besides the firing temperatures, the quality and character of a ceramic piece depend on its raw ingredients. Kaolin clay is a pure, fine-grained white clay known for its plasticity and minimal impurities. It provides strength and whiteness in porcelain bodies. Ball clay is highly plastic and often has a darker color. It improves workability and green strength, but can introduce organic matter that burns out during the firing process. Fireclay is a fixed and ground grog clay, resistant to high temperatures, which reduces drying and shrinking stresses.

Feldspar (potash and soda) is the most common flux. It melts during firing to form a glassy phase, adding vitrification. Nepheline Syenite is a low-cost alternative to feldspar, offering a similar fluxing action and added alumina. Talc contributes magnesia and acts at mid-range temperatures. Lithium carbonate significantly lowers the melt temperature, thereby enhancing thermal shock resistance.

Quartz is the primary glass former. It stiffens clay bodies, controls shrinkage, and contributes to the gloss of glazes. Silica sand is often added to bodies or glazes to adjust thermal expansion and to prevent crazing.

Used as an additive, grog is prefired clay crushed to various sizes. It lowers warping, controls shrinkage, and creates surface texture. Alumina hydrate enhances refractory properties, particularly in high-fire and sculptural bodies. Chamotte, a coarser refractory grog, is ideal for large sculptural work and kiln furniture.

Metal oxides, such as cobalt (blue, iron (browns, reds), copper (greens, reds), and manganese (browns, purples) are used as colorants, while titanium dioxide and zircon add opacity, concealing the clay body beneath a glaze, controlling gloss.

Paper clay, which is clay mixed with processed fibers, is used for lightweight, crack-resistant pieces. Sawdust or rice husk burns out during firing to create porous surfaces or a horsehair effect.

Learning ceramics involves study and hands-on practice. Resources may include studio classes, which can be accessed through local workshops or community art centers. Mentorship and guidance from experienced potters might also be available in your area. Additionally, online resources, some of which are referenced below, offer video tutorials, specialized forums, and virtual masterclasses. A starting home set can be created with a small wedging table, basic hand tools, a kiln, or access to a community firing facility. Ceramics requires consistent practice, regular making, testing various clay bodies and glazes, and studying functional and sculptural works.

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