Ceramics II Chart

CERAMICS CLAY KILN FIRING GLAZE TECHNIQUES PROCESSES CERAMIC TOOLS

Ceramics-A hard brittle heat-resistant material made by firing a mixture of clay and chemicals at high temperature. Sculpture- A Three-dimensional form that is produced through modeling (hand manipulation), slab construction, coil construction, mold making, or slip casting. Pottery-Pots, bowls, cups, plates and any other functional wares that can be produced on the potters wheel.

Clay- The product of weathered granite and feldspathic rock; a hydrated silicate of aluminum. Clay Body- Earthenware: Natural low-fire secondary clay fluxed with iron, fires porous. Often called “common” clay, found almost everywhere. Matures below 2000˚ Stoneware: Naturally occurring refractory clays. With adequate fluxes to fire in stoneware temperature range. Porcelain: High fired vitreous clay body containing kaolin, silica, fluxes, and often ball clay to increase plasticity with total clay component not more than 50% usually pure white “eggshell” in color, some porcelain may fire translucent where thin.

Kiln-The device in which pottery is fired. Kilns can be fueled with wood, oil, gas, electricity. GAS KILN: A down-draft kiln is fueled by combustible material such as gas. The air from a gas kiln moves from a burner or fire box at the base of the kiln upward into the stack area, then swirls back downward to exhaust through a chimney opening at the base of the kiln. Mid to high firings are done in a gas kiln. The environment is known as a “reduction” firing because of the lack of oxygen.

ELECTRIC KILN- Runs on electricity Known as an “oxidation” firing; allows for more oxygen in the kiln atmosphere Low-fire- mid-fire ranges Produces brighter colors; yellows, oranges, reds

Firing- The process by which ceramic ware is heated in a kiln to bring glaze to maturity; changes clay to ceramic. LOW FIRE- 1112˚-2167˚ MID FIRE- 2185˚-2305˚ 5- 8 HIGH FIRE- 2336˚-2455˚ 9- 13

Pyrometric Cones- Used to measure the amount of work the heat in a kiln has accomplished.

Glaze-A thin glassy layer on the surface of pottery. LOW-FIRE GLAZES- Lusters: Salts of metals fired at low temperatures, giving a lustrous or iridescent metallic sheen to a body or glaze surface. Underglazes: A color that is usually applied to either greenware or bisque-fired pottery and in most cases is covered with a glaze. MID-FIRE GLAZES-These glazes can be dipped or brushed on. They are fired to higher mid-range temperatures and are often not as bright or vivid in color like underglazes. These glazes, depending on the manufacturer, can be fired in both reduction and oxidation environments producing different effects. HIGH-FIRE GLAZES-These glazes are often dipped, are rich, and darker in color. These glazes produce unique characteristics that can only be achieved in a reduction atmosphere.

Techniques-A skill or procedure to produce a variety of effects with clay or on the clay surface. SGRAFFITO-A type of surface decoration that requires light carving to scrape away the top slipped-surface. The effect should be a two-toned colored surface. SLIP TRAILING-Using slip to decorate the clay surface. Depending on the thickness will leave a raised surface when fired. STAMPING-Objects such as plastic toys, clay tools, or rubber stamps can be used to create interesting textures on greenware. WAX RESIST-A liquid wax is applied to bisque ware to seal clay underneath so that it resists glazing when dipped or brushed on. Will melt in the kiln exposing the bare clay surface.

TRACING- Uses images (photos) to transfer onto clay. STENCILING-Templates can be created, taped or paper to block- out portions of the clay surface than can be sponge glazed, or brushed on glazed. Once dry, remove stencil leaving the design. MODELING- Hand building, pinching, clay manipulation, sculpture. COIL BUILDING-Snake-like ropes of clay made by rolling clay with palms of your hands and using these coils to build or construct your form. SLAB CONSTRUCTION-Flattened clay using a rolling pin or slab roller. Slabs can be used to build forms such as boxes or other containers. MOLDING-Sometimes referred to as “hump” molds, slabs that are laid over plaster or bisque fired molds. SLIP-CASTING-Molds are created with plaster using an original form, than mold is filled with liquid slip, allowed to dry, and mold is removed creating a duplicate of the original. Can be used to mass produce.

Processes- A series of procedures that produce a specific outcome, or effect. LEATHERHARD-Condition of clay where it has stiffened, but is still damp. Point at which pieces are joined and most surface modification and trimming are done. Soft leatherhard ideal for forming, joining, thick slip-decoration, joining, incising, carving, piercing. Hard leatherhard good for thin slip decoration, carving, scraping. GREENWARE-Any unfired clay. BISQUEWARE-Clay that has been fired at a low temperature ˚, once. Also called the first firing. GLAZEWARE-Pottery that has been decorated with a glaze then fired to it’s recommended temperature. Also known as the second firing. SLIP-A liquid clay body. SCORING-Scratching into the clay creating grooves for easy attachment of clay pieces. BONEDRY-Completely dried, no moisture left in the clay. WEDGING-A process of kneading the clay to eliminate air bubbles and mixed clay throuroughly.