Vocabulary

Clay— Particles of decomposed rock combined with water to create a plastic, malleable body which is then fired in a kiln to fuse the particles back into a stone-like state.

Types of Clay:

Slip— A thick and creamy mixture of clay and water used to join clay parts together or to decorate the surface. It is applied before firing, when the clay is still wet.

Earthenware— A low-fire, porous body. This is the clay we use in class. It matures at a low temperature during firing. It is more fragile than stoneware. 

Stoneware— Clay that matures at a very high temperature during firing and gets very hard.

Grog— Fired clay which has been ground up to a sand consistency and added back into the clay body. Grog adds strength to the clay.

Stages of Clay:

Slip — 

Plastic — 

Leather Hard — When most of the moisture has evaporated but clay is still soft enough to be carved or joined to other pieces.

Bone Dry — Unfired clay that has no moisture left in it. Very fragile at this stage.

Greenware — Unfired clay.

Bisqueware — Unglazed ceramic pieces that have gone through the first firing and are ready to be glazed.

Glazeware — 

Processes:

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 Terms:

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.

Decoration Terms:

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.

Liquid Underglaze (LUG)— 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.

Clay Tool Terms:

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.