Ceramics

1. Ceramics Introduction to clay terms and vocabulary

2. 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.

3. Terra cotta A brownish-orange earthenware clay body commonly used for ceramic sculpture.

4. Stoneware A high-fire clay. Stoneware is waterproof even without glaze; the resulting ware is sturdier than earthenware.

6. Porcelain True porcelain was being made in China and Korea around 960 AD. Porcelain is a combination of kaolin (a pure, white, primary clay), silica and feldspar. A unique aspect of porcelain is that it can be worked as clay, but when fired properly reaches a state similar to glass. Primary qualities of porcelain are translucency and whiteness. In the 17th Century, English potters invented Bone China to compete with the porcelain being imported into Europe.

8. Earthenware A low-fire clay. Porous and not waterproof. To be functional, it needs to be glazed.

9. Methods of forming the Clay • Coil • Slab • Pinch • Wheel

10. Coil method One of the oldest ways of forming pottery. Long strands of clay which are laid on top of each other and joined through blending coil to coil. Coil pieces can be almost any shape and any size.

12. Slab Built Clay slabs are cut to shape and joined together using scoring and wet clay called slip. Slabs can be draped over or into forms, rolled around cylinders or built-up into geometric forms. Large forms are difficult because of stresses on the seams and because the slab naturally sags. Some potters get around this by working fibers into the clay body. The fibers burn out during the firing, leaving a network of tiny holes.

15. Mold • A form used for support and shaping of the clay, usually made of paper, clay or plaster. 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.

16. Hump and Slump Molds

17. Pinch Pots Starting with a ball of clay the potter opens a hole into the ball and forms a bowl shape through a combination of stroking and pinching the clay. Many coil-built pieces are constructed on top of a pinched bottom.

19. Wheel thrown The term throw comes from Old English meaning spin. A piece of clay is placed on a potter's wheel head which spins. The clay is shaped by compression while it is in motion. Often the potter will use several thrown shapes together to form one piece (a teapot can be constructed from three or four thrown forms).

21. Plastic • Clay that is soft, pliable and easy to work with.

22. Wedging • The kneading of plastic clay in a rocking, spiral motion in order to remove air bubbles and create a uniform consistency. This can be achieved also by repeatedly slamming a ball of clay onto the table on alternating sides to force the air out.

24. Slip A fine, liquid form of clay applied to the surface of a vessel prior to firing. Slip fills in pores and gives uniform color.

25. Slip and Score • 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 clay will stick to itself when wet, but when will fall apart after bisque when all the water is removed. Texturing the surface gives the clay some grip, almost like Velcro.

26. 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.

27. Sprigging • The technique of adding an appendage or decorative element to the surface of the work using coils, stamps, molds or free-form design.

29. Leather-hard • Clay that has been allowed to dry slightly, making it stiffer and able to support its weight, but can still be worked on and have parts attached.

30. Greenware is clay that has completely dried, but not been fired

31. Kiln The furnace in which ceramics are fired. Kilns can be electric, natural gas, wood, coal, fuel oil or propane. Materials used to heat the kiln can affect the work: wood ash can build up on the surfaces of a piece and form a glaze at high temperatures. Some potters introduce chemicals into the kiln to influence the effects of the firing. Famed ceramist Beatrice Wood achieved a lustre effect by throwing moth balls into the kiln.

33. Firing Clay is hardened by heating it to a high temperature, fusing the clay particles. Primitive pottery is usually fired on the ground or in pits with whatever flammable material is available. Kilns allow a more efficient use of materials and more control over the atmosphere during a firing. The two basic atmospheres, oxidation and reduction, affect the color of the final piece. Glaze A coating of material applied to ceramics before firing that forms a glass-like surface.

34. 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 t monitor and determine kiln temperature.

35. Bisque • 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. It can no longer be slaked down and recycled.

37. Glazes can be colored, opaque, translucent or matte.

38. Glazeware • The second firing of the clay with a coating of glaze upon its surface, it is fired to a higher temperature than bisque and therefore fuses the particles into a solid, non-porous state called vitrtification.

40. Clay • Clay - decomposed rock • Wedge – knead and pound the clay to remove air bubbles • Slab – A flat piece of clay • Slip & Score – Process of scratching 2 surfaces to each other • Tools – Used to model and add texture and decoration to clay

41. Greenware- clay that has dried but not been fired yet • Glaze – Painted on after clay has been fired to add decoration • Fire- process of heating clay • Kiln – where clay is placed to be fired