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Simple Ceramic Terms
A
Antiquing
A method of applying color and wiping it
back to accentuate the detailed surface.
Airbrush
A device operated with an air compressor
used for spraying on colors, either in
overall coverage or decorative form.
B
Banding
Wheel
A turntable operated by hand, used for
decorating purposes.
Basecoat
Generally an all over coat of color on
bisque on top of which detailed decorating
is done.
Bat
A plaster disk or slab for clay work.
Bisque
Clay that has been fired but not glazed.
Sometimes referred to as "biscuit."
C
Cleaning
Greenware
The process by which mold seam lines and
surface imperfections are removed from
unfired clay objects.
Ceramics
Clay forms which are fired in a kiln.
Crawling
Glaze which pulls together and beads up,
leaving bare spots of bisque. Also referred
to as "separation."
Crazing
Tiny cracks that appear in the fired glazed
surface.
Craters
Bubbles in the glaze finish which break.
Cone
Temperature
The mixture of time and temperature at which
the cone will bend.
Cone
Plaque
A small clay cone holder used when cones are
placed on the shelf of the kiln.
Cone (pyrometric
cone)
A mixture of ceramic materials that is
designed to soften and bend when the proper
mixture of time and temperature is reached
in the interior of the kiln.
Conditioning Coat (glaze or underglaze)
A thin coat of color that will soak into the
greenware or bisque well.
Cadmium
Heavy metal used in producing red glazes and
underglazes.
Coats
Applications of ceramic color by brush,
sponge, and spray which cover an entire area
or a specific area of a piece.
China
A term which usually refers to the bone
china of England, but also is associated
with vitreous white wares and porcelain.
Cavity (of
a mold)
The inside section of a mold where the
casting is formed. Ceramics: Clay forms
which are fired in a kiln.
Casting
Slip
A liquid clay used in the process of forming
objects with molds. Also referred to as
"slip."
Casting
A clay form made from a mold. May also refer
to plaster castings.
Conditioned Brush
A brush lightly coated or dampened with a
fluid to prepare it for the application of a
specific type of color or medium. A brush
lightly coated or dampened with a fluid to
prepare it for the application of a specific
type of color or medium.
D
Dry-Brushing
A technique of applying color which produces
a feather-like effect using a dry brush and
liquid colors.
Defloculant
The alkaline substance which is added in
extremely small amounts to slip to make it
more fluid without adding excessive amounts
of water.
Dryfooting
The process by which glaze is removed from
the bottom or foot of a clay object so it
may be fired without stilting.
Dipping
The process of dipping ware into glazes.
E
Element
The heating coils of an electric kiln.
(Tired or burned-out elements refer to
elements which carry too little or no
electrical current for producing heat).
Earthenware
Porous clay bodies which are fired to
maturity at approx. 2000°F.
F
Firing
Chamber
The interior of a kiln in which the ceramic
ware is fired (also referred to as a fire
box).
Foot
The base or the part of the piece of ceramic
on which it rests.
Food-safe
A product that has been tested and
determined to be safe for use on surfaces
which come in contact with food or drink.
Firing
Cycle
A system of gradually raising and lowering
the temperature of a kiln to properly fire
ware.
Fired
Products (fired color products)
Products which must be fired.
Fired
Finish
A finish that must be fired to produce
proper color and surface finish.
Firing
The process by which ceramic ware is heated
in a kiln to bring glaze or clay to
maturity.
Finger-sand
Gentle rubbing of the glazed surface to
remove ridges.
Fettling
Lines (seam lines)
The ridges created on a casting where the
mold comes together. They are usually
removed during the cleaning process.
Flowing
Coats
An application of glaze applied with a
fully-loaded brush so the color flows onto
the surface of the ware.
G
Glaze
A fired glassy coating on a piece of
ceramic.
Gloss (G)
A shiny, glass-like finish. Greenware:
Unfired clay forms or shapes.
Grit Cloth
A rough scrubbing material used in the
process of cleaning greenware.
H
Hard Spot
An area on greenware or bisque surface that
resists color application.
Hot Spot
A section of a kiln that fires to a hotter
temperature than the rest of the kiln.
I
Incise
The process of carving a design into a
greenware surface.
K
Kiln
Furniture
The series of posts, stilts, and shelves on
which the ceramic ware rests in order to
take full advantage of the interior space of
the kiln.
Kiln
The device in which clay and glazed c!ay
objects are heated to maturity.
Kiln
Sitter (automatic shut-off)
A device used with a pyrometric cone to shut
off the kiln when conditions inside the kiln
cause the cone to bend.
Kiln Wash
The refractory coating applied to the top of
the kiln shelves to protect them from glaze
drips.
Keys (of a
mold)
The series of notches and bumps carved in
the excess plaster around the cavity of the
mold to !nsure a proper fit.
L
Lead
Release
The amount of lead that is dissolved from
the surface of a glaze which has been in
contact with acid solutions.
Leather-hard
Greenware that is taken from a mold and is
allowed to become firm but still retains its
wet look.
M
Mold Strap
(mold bands)
Devices made of cloth, rubber, or metal used
to tightly secure parts of a mold together
during the pouring process.
Matte (M)
A soft finish with little or no shine.
Matured
Bisque
A bisque that has been fired at the proper
rate of heating and cooling to produce an
even state of hardness throughout.
Mini Bars
Pyrometric cones used to measure the firing
temperature of a kiln. They are shaped like
bars rather than cone-shaped.
N
Nesting
The procedure of stacking greenware in a
kiln during the bisque firing.
Non-fired
Finish
A color that is applied to bisque. These
colors are never fired in a kiln.
O
OK
Dinnerware
A product that when applied and fired
according to label directions is safe for
use on surfaces that come in contact with
food.
Opaque (O)
Color which does not allow other colors to
show through.
One-Piece
Mold
A mold that is made up of only one section
or piece of plaster. Also referred to as an
open-pour mold because of the lack of a
pouring gate.
P
Pouring
Spare
The excess clay formed at the pouring hole
of a mold during the casting process.
Pyrometric
Cone
A small piece of clay compound that reacts
to time and temperature used to indicate
maturity of ceramic clays and glazes.
Prop
(1 ) A device of clay or refractory material
used for supporting greenware (usually
porcelain) during the firing process. (2)
Term applied to the slight opening of the
kiln cover during the first stages of the
firing process, kiln prop. (3) Another word
for kiln posts.
Pour Hole
(pour gate)
A section at the opening of the mold used
for pouring the slip into the mold cavity.
Posts
(kiln)
Articles made of refractory material which
support kiln shelves during firing.
Plasticity
Refers to the ability of clay to be formed
into a shape and retain it.
Peep Holes
(vent holes)
Small holes in the side of a kiln used for
viewing shelf cones and ventilating the kiln
during the firing process.
Pin Holes
Tiny holes in the final surface finish of a
glaze or underglaze.
R
Refractory
Material
Substances that have a resistance to high
temperatures.
S
Soaking
Cycle
A short cycle at the end of the regular
firing cycle which maintains the level of
heating in the kiln, and enhances many glaze
finishes.
Stoneware
A combination of clays which form a
stone-like vitreous body during firing.
Stilts
Small shapes of bisque with metal or wire
spurs used for supporting glazed greenware
during firing.
Stain
Unfired colors used for decorating.
Sponge
Usually refers to a natural sponge used for
cleaning and decorating greenware. There are
also synthetic sponges available for
ceramics.
Spray Gun
See airbrush.
Shelf Cone
Temperature
The cone temperature that is fired on the
shelf of a kiln. The amount of heating the
ware actually receives.
Separation
See crawling.
Semi-Transparent (ST)
Slightly colored and/or speckled colors
which allow most colors to show through with
only slight distortions.
Semi-Opaque (SO)
Colors which generally allow only dark
colors to show through.
Seam Lines
Small lines on greenware produced where two
sections of a mold are locked together
during the pouring process. Also referred to
as fettlings.
Slip
See casting slip.
Semi-Matte
(SM)
A satin-like surface which has a slight
sheen to it.
T
Test Cone
Plaque
See cone plaque.
Two-piece
Mold
A mold that has two parts.
Transparent (T)
Clear base colors which are free from
cloudiness or distortion.
Thermal
Shock
Sudden changes which occur in a clay or
glaze which causes damage, usually through
sudden heating or cooling.
Three-piece Mold
A mold that has three pieces.
Thermal
Expansion
The expansion that occurs in glazes and
clays when heated in a kiln.
U
Underglaze
A color which is usually applied to
greenware and in most cases is covered with
a glaze.
Underfiring
Not firing hot enough or long enough, or
both.
V
Vent Holes
Small holes made by puncturing the wet
greenware with a needle tool when two pieces
of ware have been attached. These small
holes allow the air and gases to escape
during firing. Also refers to the peep holes
in the side of the kiln.
Vitrified
Usually refers to porcelain and stoneware
that are fired at a high temperature. The
clay begins to become glass-like in nature,
although not necessarily waterproof.
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