Clay— a natural, earthy material made primarily of fine-grained minerals and water. It's formed through the weathering and erosion of rocks, and when wet, it becomes moldable, making it ideal for shaping into pottery and other forms. Clay particles are plate-like, making the material flexible and plastic when hydrated. When fired at high temperatures, clay undergoes chemical changes, transforming into a durable, hard material used in functional and decorative objects.
Earthenware — A low-fire clay body that remains porous after firing unless glazed. It’s often reddish-brown or white and is commonly used for decorative pottery.
Terra Cotta — A type of earthenware clay that is red-orange in color, known for its durability and use in flowerpots, tiles, and sculptures.
Stoneware — A high-fire clay body that becomes dense, strong, and non-porous after firing. It’s often gray or brown and is great for functional pottery like mugs and bowls.
Porcelain — A high-fire, fine-grained clay body that is smooth, white, and often translucent when thin. It’s used for delicate, detailed work and is known for its elegance.
Slip — A fluid mixture of clay and water.
Plastic — Very soft, malleable clay.
Leather Hard — When some of the moisture has evaporated but clay is still soft enough to be carved or joined to other pieces.
Bone Dry — clay that has dried out completely and lost all moisture, making it extremely fragile and powdery to the touch. At this stage, the clay is no longer workable or plastic and is ready to be bisque fired, where it undergoes its first firing in the kiln. Bone-dry clay is a crucial phase before firing, as any remaining moisture can cause the piece to crack or explode in the kiln due to rapid expansion of trapped water vapor.
Greenware — Unfired clay.
Bisqueware — Ceramic pieces that have gone through the first firing.
Glazeware — Ceramic pieces that have been glazed and fired.
Wedging— Kneading clay to remove air bubbles and make clay a uniform consistency.
Score and Slip— The method for joining pieces of clay where the two surfaces are scratched up and slip (or water) is added like a "glue" to create a strong, melded bond. It is an essential step in ceramic construction because the clay will stick to itself when wet but then will fall apart after bisqued when all the water is removed. Texturing the surface gives the clay some grip, almost like Velcro.
Pinch Pot— A hand-building method where the pot is formed by pinching the clay.
Coil Construction— Forming a pot from long snakes of clay which are blended together to create walls.
Slab Construction— Building a pot from rolled out sheets of clay.
Wheel Throwing— Using a potter’s wheel to form pots. Wheels can be electric or manual (kick-wheel). First, the clay is centered, then an opening is created; next, the opening is widened and the walls are raised. Each time the walls are raised, it is called a “pull”. The pot is shaped, the bottom trimmed, and the rim finished. Later, the foot of the pot is trimmed when leather-hard.
Firing— Heating the clay to a specific temperature in the kiln.
Kiln— The “oven” in which the clay is fired. Ours runs on electricity. Some are heated by gas or wood.
Bisque Firing— The first firing when the clay is heated to a relatively low temperature to remove all moisture.
Glaze Firing— The second firing during which glaze materials melt to produce a glassy non-porous coating.
Glaze— A mixture of chemicals which, when fired, create a glassy, non-porous surface on a pot. Coats of glaze should be evenly applied to bisqued pots and then glaze fired.
Underglaze — A mixture of chemicals that, when fired, create a matte surface on a pot. Underglazes do not move during the firing. They can be applied to both greenware and bisque-ware. Glaze can be applied over LUGs.
Sgraffito— Decoration carved or scratched into the surface of the clay.
Banding Wheel — A freely revolving metal or plastic wheelhead mounted on a pedestal base. Can be turned by hand and used to help with decoration and sculpting.
Bats— A flat piece of wood, sheetrock, plaster, etc. used for storing and working on pots. Round bats are used for throwing large pieces on the wheel.