Terminology


 * [[image:Grog2.jpg width="306" height="292" align="right" caption=""Grog" 1) a caveman in the comic strip "B.C"    2) a drink pirates made with watered-down rum     3) ground particulates (chunks & hunks) that shows up in clay, usually by accident but occasionally on purpose."]]Absorption**- the ability of fired clay to absorb water.


 * Annealing**- the process of cooling heated objects gradually to allow internal shrinkage to equalize without damage.

**Blistering-** When fired glaze has bubbles which can break, leaving sharp edged craters in the surface (sommetimes caused by firing or cooling too fast)

**Bagwall** - The wall on the inside of a fuel burning kiln which deflects the flame from the wear.

**Bat** - A flat disc made out of plaster, wood, or plastic which is affixed to the wheel head with clay or pins. Bats are used to throw pieces on that would be difficult to lift off the wheel head.

**Batch** - A mixture of weighed materials such as a batch of glaze or slip or a clay body.

**Banding Wheel** - A revolving wheelhead which sits on a pedestal base. It is turned by hand and used for finishing or decorating pottery.

**Bisque** - Pottery which has been fired once, without glaze, to a temperature just before vitrification.

**Bisque Fire** - First firing, without glaze. Slips can be used in a bisque firing.

**Bone Dry** - Completely air dried.

**Burnishing** - The ancient rubbing process of burnishing polishes the outside skin of a clay pot while greatly reducing its porosity. This finishing is done by hand, using a stone or a metal piece which is usually embedded in a wad of wet clay that perfectly fits the burnisher's hand.

**Calipers** - A tool used to measure the diameter of round forms, for example calipers are used to get lids to fit just right.

**Centering** - Technique to move the clay in to a symmetrical rotating axis in the middle of a wheel head so you can throw it.

**Chemical water**- trapped moisture at the molecular level that can cause breaks and blow ups in the kiln

**Chuck** - A piece used to aid the potter in trimming. A chuck is a form that can hold a pot upside-down above the wheel head while the potter trims it. Chucks are thrown and bisque fired clay cylinders which are open on both sides.

**Clay** - Alumina + silica + water.

**Clay body** - A mixture of different types of clays and minerals for a specific ceramic purpose. For example, Porcelain is a translucent white clay body.

**Coil** - A piece of clay rolled like a rope, used in making pottery.

**Compress** - Pushing the clay down and together, forcing the particles of clay closer.

**Composite Pots** - Pots that were thrown or hand built in separate pieces and then assembled.

**Consistency of Density**- while plastic, makes clay more workable, while drying, prevents cracks and crumbles

**Cone** - Pyrometric - A pyramid composed of clay and glaze, made to melt and bend at specific temperatures. It is used in a kiln to determine the end of a firing or in some electric kilns it shuts off a kiln setter.

**Crazing** - The cracking of a glaze on a fired pot. It is the result of the glaze shrinking more than the clay body in cooling process.

**Crawling** - A bare spot (from the shrinking of a glaze) on a finished piece where oil or grease prevents the glaze from adhering to pottery.

**Damper** - A slab of refractory clay that is used to close or partially close the flue of a kiln.

**Dry-Foo**t - To keep the foot or bottom of a pot free from glaze by waxing or removing the glaze.

**Earthenware** - A low fired clay body. Glazed pottery is fired to a temperature of 1,830 - 2,010 degrees Fahrenheit. Available in red or also white.

**Englobe** - Colored clay slip used to decorate Greenwear or leather hard pieces before bisque firing. Clay and oxide and water.

**Feldspar**- powdered stone that, mixed with water, makes clay (as opposed to dirt, soil, mud, earth, etc.)

**Fire** - To heat a clay object in a kiln to a specific temperature.

**Firebrick** - An insulation brick used to hold the heat in the kiln and withstand high temperatures.

**Firing** Range - The range of temperature at which a clay becomes mature or a glaze melts.

**Flux** - A melting agent causing silica to change into a glaze.

**Foot** - Base of a ceramic form.

**Frit** - A glaze material which is derived from flux and silica which are melted together and reground into a fine powder.

**Glaze** - A thin coating of glass. An impervious silicate coating, which is developed in clay ware by the fusion under heat of inorganic materials.

**Glaze firing** - The final firing, with glaze.

**Gloss Glaze** - A shiny reflective gloss.

**Greenware** - Unfired pottery. Ready to be bisque fired.

**Grog** - Fired clay ground to various mesh sizes.

**Kiln** - A furnace of refractory clay bricks for firing pottery and for fusing glass.

**Kiln Furniture** - Refractory posts and shelves used for stacking pottery in the kiln for firing.

**Kiln** Wash - Mixture of Kaolin, flint and water.. It is painted on one side of the kiln shelves to separate any glaze drips from the shelf.

**Leather Hard** - Stage of the clay between plastic and bone dry. Clay is still damp enough to join it to other pieces using slip. For example, this is the stage handles are applied to mugs. The drying stage of clay when it has lost its placticity and has achieved maximum shrinkage. Clay is firm but not entirely dry yet. AKA "Green-Hard."

**Lubricate-** Apply water to minimize friction and allow the claybody to become slippery or smooth.

**Majolica** - A low fire glazing technique. The process involves applying an opaque tin glaze to earthenware and painting it with different colored oxides.

**Matt Glaze** - A dull glaze surface, not very reflective when fired. It needs a slow cooling period or it may turn shiny. Mold - A plaster shape designed to pour slip cast into and let dry so the shape comes out as an exact replica of the mold.

**Maturing Point** - The temperature at which the clay becomes hard and durable.

**Opaque Glaze** - Non-transparent glaze, it covers the clay or glaze below it.

**Oxidation** - Firing with a full supply of oxygen. Electric kilns fire in oxidation. Oxides show bright colors.

**Peephole** - A small observation hole in the wall or door of a kiln.

**Pinch** - Manipulate clay with you fingers in your palm to a hollow shape. Pinch pots are a popular beginners project.

**Plasticity** - The quality of clay which allows it to be manipulated into different shapes without cracking or breaking.

**Porcelain** - White stoneware, made from clay prepared from feldspar, china clay, flint and whiting.

**Potters Wheel** - A device with either a manual (foot powered) or an electric rotating wheel head used to sit at and make pottery forms.

**Pug** - To mix.

**Pug Mill** - A machine for mixing clay and recycling clay. Reduction - Firing with reduced oxygen in the kiln.

**Rib** - A rubber, metal or wooden tool used to facilitate wheel throwing of pottery forms.

**Rule of Thumb**- Anything thicker than your thumb needs to be hollow, this helps with structural integrity and prevents chemical water

**Satin Glaze** - A glaze with medium reflectance, between matt and gloss.

**Slab** - Pressed or rolled flat sections of clay used in hand building.

**Slip** - Clay mixed with water with a mayonnaise consistency. Used in casting and decoration.

**Slurry** - A thick slip.

**Soaking** - Maintaining a low steady heat in the early stages of firing to achieve a uniform temperature throughout the kiln.

**Stacking** - Load a kiln to hold the maximum number of pieces.

**Stain** - Oxide and water, used as a colorant for bisque wear. Stoneware - All ceramic wear fired between 2,100 and 2,300 degrees.

**Structural integrity**- stays together, durable

**Transparent Glaze** - Transmits light clearly.

**Throwing** - Creating ceramic shapes on the potter’s wheel.

**Viscosity**- The state of being thick, sticky, and semifluid in consistency, due to internal friction.

**Vitrification** - The firing of pottery to the point of glossification.

**Wedging** - A method of kneading clay to make it homogenous by cutting and rolling.