Glossary

Absorption	Takes place when water is soaked up by biscuit-fired clay.
Accelerator	A material that increases speed of a chemical reaction.
AC motor	Motor for alternating current, which is the type of current normally supplied to house holds.
Acrylic plastic	An artificial material made from carbon polymers.
Adhesion	Bonding between two surfaces.
Ageing	Also called maturing. Storing of plastic clay under moist conditions increases plasticity.
Armature	Internal framework to support a sculpture or other structure.
Ball clay	A fine-grained, plastic clay firing to a white or buff color.
Bat	A small slab of plaster of parts used as a base for pots during forming and drying. A slab of clay used in production of saucers and plates on a jigger machine.
Batch	A quantity of products or a mixture of materials treated as one set.
Bone-dry clay	Clay that has been dried above 100_C. No moisture remains between the clay pores.
Bullring kiln	Also called bull trench kiln. A continuous kiln for firing bricks. Bricks are stacked in a ring-shaped trench and covered with a sealing layer. Chimneys are placed on top of the kiln and moved as the firing zone moves around continuously.
Calcine	To heat a (ceramic) material to a temperature high enough to release carbon dioxide, chemical water or other gases.
Calgon	Deflocculant used in casting slips. Chemically termed sodium hexametaphosphate.
Chuck	A tool used to hold pots or other items while they are worked on.
Clay body	A mixture of different clays and other materials like grog, feldspar and talc. Clay is a natural product; clay body is man-made.
CMC	An organic binder based on cellulose. Chemically termed carboxymethyl cellulose sodium salt.
Coir	The outer husk of coconut used for making ropes.
Continuous kiln	A kiln fired continuously. In tunnel kilns the ware is moved through the firing zone. In ring kilns (Hoffmann kilns) the firing zone is moved.
Crockery	Clay pots used in the household.
DC motor	Direct current motor. A battery supplies direct current.
De-airing	Removing air from plastic clay by exposing it to a strong vacuum. It improves plasticity and reduces lamination problems.
Deliquescent	A material (salt) that easily absorbs moisture from the air.
Density	The modern term for specific gravity. The number of times a material is heavier than the same amount of water. If a slip has a density of 1.7 it means that 1 liter slip weighs 1.7 kg.
Dewatering	Removing water from a clay slip in order to get a plastic clay.
Extrude	Shaping of a plastic material like clay by forcing it through a die.
Fettling	Trimming rough edges of pottery before firing.
Fireclay	A clay that can withstand high temperatures though it may not fire to a white color. It is used for making refractory materials.
Flux	Material that lowers the melting point of a clay body.
Frit	Is made by melting several glaze materials to a glassy mass which is ground and used in a glaze. Frit added to a body or a glaze lowers its melting point.
Fulcrum	The point against which a lever turns.
Granule of clay	A small grainlike mass of clay particles.
Grog	Fired clay that has been crushed. Grog is added to clay to reduce drying cracks or to reduce thermal shock cracks in kiln furniture or firebricks.
Household ware	Pottery used in the household.
HP	Abbreviation for horsepower, a measurement of how much work a machine can do. 1 HP = 0.7457 kilowatts.
Hydrostone	A special hard plaster that is capable of making plaster mixtures with much less water than normal plaster .It is used for making models, master and case moulds and press moulds.
Kiln furniture	Shelves or slabs, saggers, posts or stands, used for placing ware in the kiln during firing.
Kneading	Manually work up clay for the purpose of mixing it better, getting air pockets out of it, and making it softer. Kneading is done immediately before clay is used for forming.
Lamination	Separation of materials in layers. Often seen in pressed tiles and in extruded clay products.
Low tension insulator	A glazed ceramic item used for insulating electric wires for currents below 440 volts.
Overglaze	Decoration with colorants on top of other already-fired glazes. The firing of over glaze decorations is done at a lower temperature than the original glaze firing.
Plastic	A plastic material (like clay) has the ability to be moulded easily. Acrylic plastic is often just called plastic.
Porosity	Ability of fired clay to absorb water. After firing the pores between the clay particles can hold water.
Refractories	Materials or products like firebricks, kiln slabs, etc., which can withstand high temperatures without melting.
Relief designs	A clay surface can be moulded so that some parts stand out from the rest of the surface. It is a picture in three dimensions.
r.p.m.	Abbreviation of revolutions per minute. A potter’s wheel may rotate at 200 r.p.m.
Sanitary ware	Ceramic ware used in bathrooms and for disposal of sewage.
Slip	Mixture of clay and water. Used in casting and for joining leather-hard clay pieces.
Smokeless stove	A stove for cooking provided with a small chimney that takes the smoke from the cooking fire outside the house.
Smoking	A potter’s term used for the first period of firing a kiln with greenware. During this period all moisture is released from the clay and the water vapor looks like smoke.
Tableware	Items like plates and cups used for eating at the easily.
Vitrified	When clay is fired to a high temperature it starts to melt. It is vitrified when after firing it is hard and brittle and absorbs little water.
Warping	Deformation of ceramic items caused by uneven drying or overfiring.
Wax	A long strip of clay extruded from a die.
Wedging	A manual method of preparing plastic clay. A lump of clay is thrown forcefully onto a solid table. It is then cut in two, one half then being thrown down on the other half. This is repeated 20-50 times.