- Ball Clay.-A natural
clay which is the most plastic of all clays. Often mixed with other
clays to make them more plastic.
- Bat.-A plaster of Paris
slab, used to absorb moisture from wet clay. See part II, lesson VIII.
- Blanks.-China ware and
tiles fired with a white glaze, upon which overglazes are often applied.
- Bisque.-Biscuit, terra
cotta-unglazed clay fired until chemical water is driven off.
- Body.-Clay which is ready
for use, raw or compounded.
- Bone Dry.-Unfired clay
which has been air dried to the maximum at room temperature.
- Bone China.-China ware
in which ashes of calcined bones are added to the clay body to increase
translucency of the china.
- Calcined.-Made powdery
by the action of heat.
- Casting.-The process
of making reproductions with clay slip in plaster of Paris molds.
- Ceramics.-Art of creating
and making fired clay objects.
- China Stone.-Petuntze;
one of the major ingredients of porcelain, which gives it translucency
and acts as a flux in firing.
- China Painting.-The
painting on china with overglaze colours.
- Dipping.-A method of
applying glaze to ceramic objects, by dipping into a bucket or pot of
- Earthenware.-A coarser
heavier type of clay ware, glazed or unglazed, pertaining to utility
ware and generally undecorated.
- Clay Body.-The clay
from which the ceramic object is made.
- Coil Method.-A procedure
for making clay objects from plastic clay coils or snakes.
- Compounded Clay.-Clay
body which is made by blending several clays and minerals together,
as opposed to clay found in the natural state.
- Cones.-Pyrometric pyramids
used to determine maturity during firing.
- Consistency.-The degree
of firmness, density, viscosity, plasticity, etc.
- Covering Quality.-The
degree with which a glaze obscures the clay or other glazes beneath
- Cracked.-The position
of the kiln door when barely open.
- Crazing.-The effect of
crackle glazes; tiny fracturing of the glaze surface.
- Curing.-The process of
permitting moist clay to rest until it attains a uniform moisture density
- Decorating Wheel.-A
rotating device upon which objects to be decorated can be placed to
assist the decorator.
- Delft.-Types of English
and Dutch ware which employ opaque tin and lead glazes, generally using
shades of cobalt blue colour decoration.
- Drain.-The act of removing
the excess slip from a mould during casting. See lesson VII.
- Dresden China.-Porcelain
china from Dresden where the first true porcelain was made in Europe.
- Embossing.-Placing a
raised clay decoration on the surface of a ceramic object-such as in
certain types of Wedgwood ware.
- Enamel.-A highly glossy,
highly covering glaze.
- Engobe.-A clay slip
generally used for slip painting or covering the clay body beneath.
See lesson X.
- Faience.-A type of ceramic
ware originally made in Faenza, Italy, and later made in France. Like
Delft it employs a lead-tin opaque covering glaze.
- Feldspar.-A constituent
of crystalline rock comprising aluminium silicates with potassium, sodium,
calcium or barium. When decomposed it becomes Koalin.
- Firing.-The act of applying
heat to ceramic ware.
- Firing Cycle.-The period
from when heat is first applied in a kiln until the fired ware has completely
cooled and is ready to be removed from the kiln.
- Flint.-A very hard kind
- Flood Mould.-A one-piece
mould. See lesson VII.
- Flux.-A substance which
assists in the melting of metals or minerals when heat is applied.
- Frit.-Pulverized glass
of various kinds.
- Fuse.-Liquefy or melt
- Gate.-Opening in an
assembled mould through which casting slip is poured into the mould
cavity, through which the air escapes, and through which the excess
slip is drained off.
- Green Ware.-Unfired
clay either in leather hard or bone-dry condition.
- Grog.-Crushed bisque;
used sometimes in larger clay objects to prevent warping when fired.
- Gum.-A solution of gum
Arabic or tragacanth used to hold underglaze colours in place until
- Gypsum.-Hydrous calcium
sulphate which, when calcined, forms plaster of Paris.
- Incising.-The act of
cutting into with a sharp instrument, as in carving and engraving.
- Keys.-The mounds and
depressions in opposing faces of mould pieces which fit together exactly,
retain, and insure the proper position of the pieces.
- Kick Wheel.-A type of
potter's wheel which is rotated by applying the foot against the fly
- Kiln.-An oven in which
ceramic ware is fired.
- Kiln Wash.-A slip made
of pulverized koalin and flint and applied to kiln floors and kiln furniture
when firing glazed ware.
- Koalin.-One of the principle
ingredients of porcelain clay.
- Leather Hard.-Condition
of moist clay when sufficiently dry to be no longer plastic.
- Luster.-Metallic overglaze
which, when fired, forms a thin metal sheen or gloss.
- Majolica.-A type of ceramic
pottery developed in Italy during the Renaissance, with high glossy
glaze; a type of opaque glaze with high gloss.
- Maturing.-The temperature
at which particular clays and glazes attain their desired quality and
- Matt Glaze.-A
type of glaze which is nonglossy, satiny in appearance, and feels like
- Model.-The object from
which reproductions are duplicated, or from which plaster of Paris molds
- Mould.-An assembly of
plaster of Paris pieces containing a cavity in which castings are formed.
- Mould Marks.-Ridges
formed on castings where clay slip has run into the seams where two
pieces of the mould come together.
- Muflie.-The walls of
a type of kiln which prevent the open flame from coming in contact with
- Overglazes.-Ceramic colours
or lusters which are applied over glazed surfaces for decorative effects,
and fired thereon.
- Plaster of Paris.-Calcined
gypsum used in making molds, bats, and models.
- Plastic.-A condition
of moist clay during which it can be easily modelled by hand, but will
retain its shape without collapsing.
may pertain to a type of engobe decoration.
- Porcelain.-A high firing,
hard, translucent, fine texture china, comprising fusible petuntze and
nonfusible koalin; the finest ceramic clay body known.
- Potters' Wheel.-A rotating
device upon which plastic clay objects are formed by hand.
- Pottery.-Fired objects
made from raw clays.
- Pressing.-A method of
working plastic clay by forming around a model.
- Press Mould.-A type of
open mould into which plastic clay is pressed to form it in the desired
shape. See lesson VIII.
- Pouring.-The putting
of slip into a plaster of Paris mould.
- Proving Colours.-The
application of underglaze, glaze, and overglaze colours on tiles, and
firing to maturity to establish the true final colours, prior to their
use on other ceramic ware.
- Raw Clay.-An
unblended or noncompounded clay; as found in the natural state.
to fuse, heat resistant.
- Sagger.-A fire clay
box in which ware is stacked and sealed to avoid contact with flame
in open flame kilns.
- Salt Glaze.-A rough,
thin transparent glaze caused by volatilizing salt in the kiln, which
salt deposits itself on the ware as a glaze upon cooling.
- Separator.-Moist brown
soap film applied to a model to prevent adhesion of plaster of Paris
formed around it; and to facilitate the removal of the model from its
- Sgraffito.-A type of
engobe decoration. See lesson X.
- Sevres.-A fine type
of French ceramic ware.
- Slip.-A liquid consisting
of clay suspended in water.
- Slip Painting.-The painting
of engobe on clay objects. See lesson X.
- Slip Pasting.-A procedure
by which plastic and/or leather hard pieces of clay are caused to adhere,
using clay slip as the adhesive.
- Soft Paste.-Chinese soft
paste is porcelain to which soap stone is added to lower its maturing
temperature. English soft paste is bone china. European soft paste was
made in an attempt to imitate the translucency of porcelain by adding
frit. Soft pastes are all low firing bodies.
- Spare.-The part of a
clay casting, formed in the gate of a mould, which is cut away after
pieces of the mould are removed.
- Splice.-A method of
joining coils, snakes, or other pieces of plastic clay.
- Stacking.-The loading
of a kiln with ware to be fired.
- Staffordshire.-A well-known
type of English ceramic, ware.
- Stilt.-A type of kiln
furniture for supporting ware to be fired.
- Stoneware.-A high firing,
hard, nonporous coarse type of ware, of grey or brownish colour.
to the sense of touch.
- Thermal Shock.-The result
of a too sudden rise or fall in temperature on ceramic ware.
- Throwing.-The process
of forming objects on a potter's wheel.
- Triangle.-A type of kiln
- Turning.-A process of
cutting the surface of thrown objects with scrapers, to a fine finish.
- Undercut.-A portion of
the model which folds in or under. in such a way that if plaster of
Paris is formed on it, the plaster mould cannot be removed without damage
either to the model or mould.
stains used for decoration which are applied to green ware or bisque
before glazing. See lesson XI.
- Vitreous.-Glassy or
- Vitrify.-To change into
glass or a glasslike substance by the application of heat to fusion.
- Wedgwood.-A fine type
of English ceramic ware characterized by the use of finely designed,
embossed, or bas relief, classical, clay decoration on stained bisque
- Wedging.-The process
of kneading or working plastic clay until it has a uniform consistency
throughout, and is free of air bubbles or pockets. Also, the process
of working one piece of plastic clay into another piece. See lesson
- Wetting Agent.-Water
glass used in casting slip to reduce the amount of water necessary for
proper slip consistency.