Hand Building Vocabulary
We put together this post to help you find common terms of Hand building and the process of creating pottery.
Hand Building Vocabulary
Clay - A naturally occurring aluminum silicate composed primarily of fine-grained minerals. Clay deposits are mostly composed of clay minerals, a subtype of phyllosilicate minerals, which impart plasticity and harden when fired or dried; they also may contain variable amounts of water trapped in the mineral structure by polar attraction. Organic materials which do not impart plasticity may also be a part of clay deposits.
Types of Clay:
Terra Cotta - A low fire red clay body.
Porcelain - A high fire transparent clay body that you fire to Cone 5 or 6, 8 or 10 (depending on the clay body) to mature.
Stoneware - A high fire clay body that fires to maturity over 2100 degrees.
Hand Building - Sculpting any clay body by hand. Most often ceramic tools are used to carve, engrave, incise the clay.
Coil - Rolling out wet clay into rope like pieces. Pieces can then be stacked to form and build a piece like a cup or vase.
Pinch Pot - Simple clay vessels such as bowls and cups of various sizes can be formed and shaped by hand using a methodical pinching process in which the clay walls are thinned by pinching them with thumb and forefinger.
Slab - By forcing a lump of clay through a roller mechanism (slab roller), flattening the clay to a consistent thickness. Slabs can be used to build sculpture or functional vessels, and often gives the artist more freedom to alter a form from the beginning of the process, rather than after a basic form is wheel thrown or coil built.
Throwing - Creating objects on a potter’s wheel.
Extruder, Extrude, Extruding - Machine that forces plastic clay through a die to produce extruded clay shapes.
Slump Mold - A typically shallow frame or mold into which a slab of clay is allowed to fall or settle in order to form a vessel. These can be frames with no bottom
Hump Mold - hump molds or drape molds are convex ceramic forms. An advantage that they have over slump molds is it enables you to add feet and handles to the outer surface of the piece.
Score - To rough the surface of the wet clay in order to attach another piece of wet clay.
Impressing- Decorating technique where textured or patterned material or object is pressed into clay surface.
Wedging - Method of kneading clay to get rid of air pockets in the clay.
Leather Hard - The damp but stiffened stage in drying clay. Typically a great time to add handles or other additions so the body of the piece doesn’t warp.
Bone Dry/Greenware - Any unfired clay body before it is Bisque Fired and is very fragile. Unfired clay that is free of water and only contains the amount of moisture in the atmosphere.
Underglaze- Colors that can be painting on greenware or bisque that will show through a clear overglaze
Decorating/Branding Wheel - A wheel that will turn to allow for ease in decorating
Sgraffito - scratching designs on pottery
Kiln - A special furnace that reaches high temperatures used for firing clay products. Kilns can be electric, gas or wood-firing.
Bisque - Unglazed clay body fired to a low temperature - typically fired to Cone 05/06 or around 1945 degrees at slow speed. During this process all moisture and gases are taken out of the clay body.
Bisqueware - The state of clay when it comes out of the kiln. It is a permanent state and is hard enough to have glaze applied.
Glaze - Noun - A ceramic paint typically composed of opaque or transparent colors which becomes vitreous when fired to maturity.
Glaze Firing - Typically the second firing of a ceramic clay body after it has been Bisque Fired. The temperature for the Glaze Firing will depend on the clay body and the glaze.
Glaze-resist/Wax - Decorating technique where resist materials are applied to prevent glaze from adhering to certain areas.
Paper Resist - Decoration technique where strips of moist or adhesive paper are adhered to the surface to resist application of slip or glaze.
Thermal Shock - Breakage of a ceramic piece caused by sudden temperature changes.
Crawling: When the clay doesn't stick to glaze (This is because the dust on the clay was not cleaned)
Crazing - Very fine surface cracks in fired glaze surface—technically a fault in glazed wares, but often sought after, especially in raku.
Bloating - Firing defect where blisters form within claybody, raising large lumps on the surface.
Blistering - Glaze defect where fired glaze surface contains bubbles, which often break open to leave sharp-edged craters in surface.
Pinholing - Glaze defect characterized by fine pinholes in the surface—often caused by pinholes already present in dry unfired glaze coating. Can also be caused by burst bubbles in glaze surface that are not given opportunity to “heal” at end of firing.
Warping - Distortion of clay forms caused by uneven stresses within clay due to forming method, uneven drying, uneven support in firing, or uneven or excessive heat in firing.
Ceramic Luster Glaze - Metallic overglaze finish created either by painting prepared luster (metallic salt in organic binder) over previously fired glaze and firing to cone 018 or by spraying metallic salt dissolved in water into kiln and/or on to wares at low red heat, either during cooling cycle of a glaze-firing, or in a separate firing heated to that temperature
Shrinkage - Permanent contraction of the clay in both drying and firing stages.