Clay is decomposed granite

Primary clay

• Primary clay is relatively rare. It is clay that is found at the same place the rock broke down.

• Very white in color

Secondary clay

• secondary clays have been transported by wind, water or both from their places of formation.

buff, brown, or red color

Earthenware

• Low-fired ware, usually still porous after firing—must be sealed with glaze to be functional.

Stoneware

• literally as hard

and durable as stone.

• Used for plates and mugs

Porcelain

• Porcelain can informally be referred to as "china" or "fine china” as China was the birthplace of porcelain makin. The highest temperature as well and most temperamental clay body. It is the purest form of clay possible, it is white and has translucent capabilities.

Paper clay

• Uses a claybody or slip containing paper pulp, which reduces shrinkage in drying stage, and is easy to join pieces together.

• Very strong and easy to work with.

STAGES OF CLAY

• Plasticity(noun):refers to how flexible a clay or clay body is. Any particular clay's plasticity is greatly influenced by the clay's particle size, water content, and aging.

Leather hard

• Leather-hard (adjective) At this stage, the clay is still visibly damp (usually a darkish gray) but has dried enough to be able to be handled without deformation. The clay is able to be carved without breaking, but will not receive impressions.

Greenware- period when the clay is completely dry

Bisqueware

• The first firing for the clay, removes all of the water, (both actual and chemical) and carbon, The fusing of the particles has begun, yet the clay is still porous to allow for glaze absorption.

• The clay has been painted with a glass-based paint (called Glaze) and has been fired again... this is what makes the glaze paint so shiny!.

HANDFORMING TECHNIQUES

• Pinch • The process of

starting with a ball of clay, inserting your thumb and "pinching" the clay between your thumb and fingers, gradually expanding and shaping the wall into a bowl-like form.

coil

• Coil pots are made when clay is rolled into thin snake-like ropes and then layered on top of one another. Often times the outside and inside of the pots are smoothed so the coils are not obvious

slab

• Using thin sheets of clay to build a structure, the sheets can be either rolled or stretched out.

Press pot

• A form is used for support and shaping of the clay. Soft slabs are draped on top or slumped inside and allowed to get leatherhard and then built upon or cut and shaped further. Clay can be pressed into plaster molds with a design carved or cast into a negative space and then popped out and attached.

Wheel throwing

• Putting clay in the center of an electric wheel to form the pottery.

• Kiln –clay oven• A furnace made of

refractory (non-melting) materials constructed to fire clay. They are usually fueled by electricity, gas or wood, but may also be fired using coal, oil, manure or even old tires.

• Cone • A pyrometric cone is a

triangular shaped piece of ceramic materials carefully formulated to melt at a specific temperature. They are placed in the kiln to monitor and determine kiln temperature. However, we use a computerized cone. So, for us the cone is the temperature at which the clay is fired.

• Stamp • Any device that

can be pressed or rolled into clay to create an imprinted design. It can be made of clay, plaster, wood or a found object

• Sprigging • The technique of

adding an appendage or decorative element to the surface of the work using coils, stamps, molds or free-form design

Glaze

• A mixture of powdered ceramic materials

clay, glass, fluxes and colorants in suspension with water. It is applied to bisqeware and then re-fired to a higher temperature (usually). Glaze is used to decorate, protect and make the ware food-safe. Do Not apply glaze to the bottom surface of the work or the any part that may rest upon or touch the kiln shelf.

• 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

• Slaking: • Adding water to dried up clay to make it plastic again.

Grog- pieces of brick or sand added to clay to make it strong

• Wedging-pounding of the clay over and over to get rid of air bubbles

Air bubbles?

• If your clay has air bubbles the clay could explode.

• Water gets trapped in the air bubbles. The water begins to steam and the steam explodes the clay.

• CANDLING:• When you preheat

the clay for 24 hours to 180 degrees to release water gently.

• Almost totally reduces the threat of blowing up the clay.

Phases of Firing

• Preheat (candling)-180 degrees

• 428 degrees-initial breakdown of plant materials in clay. (smelly time).

• 572- 1292 degrees- release of chemical water.

• Chemical water has a strong electrical charge that binds it to other molecules that may be attached to it.

http://www.youtube.com/watch?v=mww6XOYYhtA