EARTHENWARE - A low fired clay which remains porous
when fired ( usually under 2000º )
STONE WARE - A high fired clay which becomes non - porous when fired
( usually over 2000º )
PORCELAIN - A strong, non - porous, white clay body which matures at 2345º or higher.
WEDGING - Kneading clay in order to take out air pockets and make it more workable.
PLASTICITY - The quality of clay which permits it to be readily shaped into
different forms without cracking, crumbling, or sagging.
SLIP - A mixture of clay and water to the consistency of heavy cream.
GREENWARE - Any clay form that has not yet been fired.
LEATHER HARD - The condition of unfired clay when most of the moisture has
evaporated leaving it still soft enough for joining or carving.
BONE DRY - The condition of unfired clay that has no moisture remaining in
it.
BISQUE - Clay which has been fired once, usually unglazed. Cone 04 to 06.
FIRING - To heat in a kiln to a desired temperature.
KILN - A type of furnace or oven used to fire clay and able to withstand high
temperatures.
FOOT - The base of a ceramic piece.
BAT - A slab or disk of plaster, wood, or other material used for supporting
clay work in progress.
RIB - A tool usually made from plastic, wood or metal which is used to shape
a pot.
BANDING WHEEL - A rotating work base useful for building or decorating ceramics.
PIN TOOL - A tool consisting of a metal or wooden handle with a pin attached.
Used for cutting or scoring clay.
SLIP AND SCORE - The technique used to join two pieces of clay. Pieces to be
joined are scored or roughed up and slip is added between them to make a strong
bond.
SEA SPONGE - A natural sponge used for a variety of purposes. Preferable to
a synthetic sponge because of for its ability to hold more water.
STAIN - A prepared ceramic colorant. A diluted coloring oxide made to produce
one definite color.
GLAZE - A glass like coating which is bonded to a ceramic surface by heat.
GLAZE FIRE - The second firing process in ceramics during which materials melt
and fuse to the surface of a ceramic piece.
GROG - Hard fired clay that has been crushed or ground to various particle
sizes. Grog is added to clay to reduce shrinkage.
TERRA COTTA - An earthenware clay, generally red in color and containing grog.
It is commonly used for ceramic sculpture due to its ability to resist warping.
ENGOBE - Engobes are sometimes just called slips, but this term refers to a
prepared slip with colorants added. Primarily used for decoration of greenware.
SGRAFFITO - Decoration achieved by scratching through a colored slip to show
the contrasting clay color underneath.
MISHIMA - A decorative technique in which Incised lines are filled in with
a colored slip or contrasting clay. The surface is then scraped flush, revealing
the design underneath. This technique is thought to have originated in Korea.
SLIP TRAILING - Decoration achieved by applying fluid slip to leather hard
clay using a bottle, syringe, or pastry bag. This technique for creating raised
patterns on the clay was popular in Colonial America and earlier in England.
MARBLING - Marbling is sometimes referred to as wet slip trailing. Contrasting
colored clay slips are thinned with water and applied to a surface. As the
two slips mingle the distortion is exaggerated by shaking the piece or rapping
the underside.
FEATHERING - A decorative technique in which slips are painted or trailed in
lines of contrasting colors. A pointed object such as a fork, pen, cake decorator
or feather tip is run through the slips creating a zigzag effect.
UNDERGLAZE - Colored decoration applied on bisque ware before firing. Underglazes
differ from gloss glazes in that they do not run or drip, and are therefore
suitable for the painting of intricate designs. In order to achieve a glossy
appearance, underglazes usually must be given a coat of clear glaze.
RED IRON OXIDE - A pure oxide which can be mixed with water to make a reddish
brown stain that can be applied to bisque ware to bring out textural qualities.
BLACK IRON OXIDE - A pure oxide which can be mixed with water to make a grayish
black stain that can be applied to bisque ware to bring out textural qualities.
FETTLING KNIFE - A general purpose knife consisting of a long, hard steel blade
and wooden handle. It is used for many trimming, carving and sculpting tasks.
SHUR - FORM RASP - A tool which is a type of rasp with a handle. Shur -
form rasps are often used to plane the sides of slab built objects and
ceramic
sculptures.
TEST TILES - Small fired tiles made by ceramic artists to test glaze results
and combinations.
STILT - A ceramic tripod upon which glazed ware is placed in the kiln to prevent
sticking.
CRAWLING - Blank or bald spots which appear on a glazed piece after firing.
Crawling may be caused by a dirty or dusty bisque surface, or by applying the
glaze too heavily.
PEELING - Separation of slip or glaze from the clay before firing. Peeling
may be caused when slip is applied to clay that is too dry, or when a glaze
is applied too heavily or to a dusty surface.
PUG MILL - A machine used for mixing plastic clay. Often used to recycle clay
scraps. Some models have pumps attached which remove air from the clay before
it is extruded.
