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A
Absorption
Degree of moisture that will soak into plaster when casting, or into bisque when glazing or decorating with nonfired colors.
Accenting
Emphasizing an area with lighter or darker colors, by shading or outlining.
Add-Ons
Greenware parts added to main casting (ex. handles to cups). See Stick-Ons.
Adherence
Ability of a glaze, underglaze or nonfired color to stay in place on a given surface.
Aging
Letting newly mixed casting slip set, undisturbed, for several days. During this aging period, all the materials will become properly blended and produce the best casting qualities.
Airbrush
Small spray gun used for applying glazes, underglazes or nonfired colors. Also used for shading and general decorating.
Alumina Hydrate
A mineral that, in a powder form, prevents porcelain or stoneware greenware surfaces that touch from fusing together during firing or from adhering to kiln shelf.
Antique Brass and Antique Bronze
Special effect glazes that produce polished metal-like surfaces.
Antique Glazes
Trade name of glazes with a frosted look and variance of color tones.
Antiquing
Removing applied color to accentuate detail.
Antiquing Gels
See Water-Based Antiquing Gels
Appliqué
Applying material such as lace, string, grog, etc. to ware; name of a type of ceramic add-on.
Art Glazes
Trade name of glazes that produce a blend of colors within themselves.
Automatic Shut-Off Device
A mechanical device triggered by a small cone that shuts off the kiln.
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B
Banding
Applying color to ware in decorative bands.
Banding Wheel
A hand-operated turntable used to apply or blend bands of color and to accomplish other types of decorating.
Bar, Pyrometric
See Cone
Binder
Material added to hold ceramic ingredients together, such as gum arabic.
Bisq-Stain® Opaques
Trade name of nontoxic nonfired acrylic colors for bisqueware. Can also be used for accenting pattern in Crackletone Glaze.
Bisque
Fired, underglazed objects of clay. Hard bisque, witness cone 04 or higher; soft bisque, witness cone 06.
Blistering
Broken bubbles on fired glaze surface.
Blunger
A container, with agitator, for mixing slip.
Body
Term used to describe any formula of clay.
Bone China
Articles made from a clay body that includes bone ash for translucency and strength.
Bone-Dry
Term used to describe greenware that is completely dry, containing no free moisture.
Brush Cleaner
A cleaner and conditioner for brushes.
Butting
Term used to describe placement of two or more glazes in close proximity on the same piece. The second glaze is applied so that it comes within the width of a pencil-point line of the first glaze but does not touch it. If the glazes accidentally touch, the area is scraped clean with a cleanup tool,
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C
Casting
The process of filling a plaster mold with casting slip, thus creating a clay object.
Casting Slip
Liquid clay for mold casting
China
Special type of high-fire clay body that has a translucent quality.
Clay Carbon
Carbonless paper for transferring designs onto greenware.
Cleaning Greenware
Removal of mold seam lines and imperfections from unfired clay objects. See Greenware Preparation.
Cleanup Tool
A tool used to clean greenware.
Concepts® Underglazes for Bisque, Majolica & More
Trade name of nontoxic underglazes used for translucent, semi-opaque or opaque color coverage. Ideal for contemporary and classic design.
Cone or Bar, Pyrometric-Heat
Measuring device used when firing a kiln. A bar or a three-sided pyramidal form made of ceramic materials, which react, to time and temperature in the same way ceramic ware does in a kiln.
Cover-Coat®
Trade name of nontoxic opaque underglazes used for full color coverage. Also used for decorative purposes.
Crackles™ Glaze
Trade name of glaze that has been especially formulated to produce a delicate “crazed” surface pattern.
Cratering
Moon-like craters on a glazed surface.
Crawling
Term used to identify a glaze defect in which the glaze pulls away or crawls from the bisque, leaving bare bisque areas
Crazing
Hair-like cracks which appear on a fired glaze surface. Often referred to as either immediate or delayed crazing.
Crevice
A recessed area of greenware or bisque.
Crosshatch
To apply second and third coats in a series of parallel strokes that intersect.
Crystaltone™ Glazes
Trade names of glazes combined with crystals that melt in the firing to form interesting patterns.
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D
Debut Brushes
Trade name of Duncan Taklon brushes.
Decal
A picture or design, printed with ceramic colors (underglaze or overglaze) on special paper, which can be transferred to the surface of the ware and fired for permanency.
Decorating Wheel
See Banding Wheel
Decoupage
A process whereby a cutout design is applied to ware after which the ware receives several coasts of lacquer or sealer.
Deflocculent
An alkaline substance added to slip to increase flowing qualities without increasing water content.
Dinnerware Safe
Term used for a glaze that complies with the Food and Drug Administration’s safety requirements concerning lead and cadmium release when properly fired to witness cone 06.
Dipping
Coating an object with liquid glaze by immersion in a container of glaze.
Discovery Brushes
Trade name of a line of Duncan brushes.
Drybrushing
Effect achieved by applying color very lightly with an almost dry brush.
Dryfooting
Leaving the bottom area of an article unglazed so stilting is unnecessary. Not recommended for low-fire ceramic utility items due to the porosity of the ware.
Dunting
Breaking away of clay body during firing, due to trapped air or foreign substance.
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E
Earthenware
Nonviterous ware made from low-fire clays.
Element
A high-temperature resistance wire wound in a coil that carries electrical current for heating kiln.
Elephant Ear
Fine-grained, thin sponge.
Embossed
A raised design.
Engobe
Colored slip or clay. Also the term used when decorating an unfired clay object with colored casting slip or liquid clay.
Envision™ Glazes
Trade name of nontoxic lead-free translucent, opaque and speckled glazes. Can be mixed, blended and layered for translucent to solid opaque coverage.
E-Z Stroke™
Trade name of nontoxic premixed translucent underglaze colors for detail work, linework, color washes, etc.
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F
Ferrule
Metal band of brush to hold hairs or bristles in place.
Fettling Knife
Tool used to remove excess clay from the outside of the mold and from the mold pour hole.
Firing
The process of maturing ceramic products by various degrees of heat.
Firing Chamber
Inside area of kiln.
Firing Cone
See Firing Basics
Flash
The undesirable transference of a soft glossy sheen onto unglazed ware when high fired glazed and unglazed ware are fired together.
Flash Casting
Cleaning a mold by making a thin casting with a different slip to pick up any traces of the last-used clay body.
Flashing
Shiny edges on ware which many low-fire glazes show when high fired.
Flow
The term used when referring to the running or moving qualities of a glaze.
Flowing Chart
A coat of glaze applied with a well-loaded brush, so that the brush does not drag against the surface of the ware.
Flux
Any substance added to clay or glaze to lower maturing temperature.
Foot
Bottom of ceramic item.
Free-Form
Shape with no uniformity.
French Dimensions
Trade name of nontoxic high-pile glazes for raised design effects over and under glazes, and over each other.
Furniture
Articles necessary to use full capacity of kiln space. Shelves, posts and stilts.
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G
Gallery Opaque Glazes
Trade name of a family of opaque glazes.
Glaze
A fired finish consisting of a prepared mixture of frit that produces a glass-like surface when fired.
Glaze Brush
A brush with long full hairs for application of glaze and opaque underglaze.
Glazes, Nonflowing
See Nonmoving Glazes
Gloss Glaze
Shiny Glaze
Graining
To create a wood-grained effect by incising greenware or using thinned nonfired colors applied in a wood-grain pattern.
Granite Stone
Trade name of nontoxic nonfired water-based textured colors with sparkling flecks.
Greenware
Unfired clay articles.
Greenware Drill
A small tool with a threaded point used for drilling holes in dry greenware.
Greenware Preparation
Removal of mold seam lines and imperfections from unfired clay objects.
Greenware Saw
A small tool with a serrated edge used for cutting dry greenware.
Grit Cloth
An abrasive cloth for cleaning greenware or bisque.
Grit Sponge
A square sponge with an abrasive surface on one side.
Grog
Ground up bisque added to clay to reduce shrinkage and add strength. Sometimes changes texture and color.
Guard Cone
One cone hotter than the desired cone.
Guide Cone
One cone cooler than the desired cone to signal the approach of maturity.
Gum Arabic
Material added to hold ceramic ingredients together.
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H
Hard Bisque
Ware that has been fired to witness cone 04 or hotter.
Hard Spots
Areas that will reject color, and sometimes cause ware to have bare spots. Can be caused by over sponging greenware, but is generally caused by improper greenware casting.
High-Fire
Refers to ceramic articles or glazes that are fired to witness cone 4 or higher (stoneware or porcelain).
Hydrometer
Device to measure density of liquids.
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I
Immature Bisque
Ware that has been fired cooler than witness cone 06.
Imperious
Impenetrable; often used as another term for waterproof.
Incising
To cut clay surface to create design.
Incompatible Colors
Ceramic colors unsuitable for use together because of unbalanced chemical effects.
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K
Kaolin
A clay used in certain clay bodies for whitening. Main ingredient in porcelain.
Kiln
A heating chamber for hardening and maturing clay and glaze.
Kiln Furniture
See Furniture
Kiln Wash
Coating used on the tops of kiln shelves and kiln floor to protect them from glaze drippings.
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L
Lace Tool
Long, pointed tool for use in applying lace.
Leather-Hard
Term used to describe cast or hand-formed clay items that are damp but firm enough to handle without losing shape.
Liner Brush
A brush with long pointed hairs for fine lines and design work.
Liquid Pearls
Trade name of nontoxic nonfired pearlescent water-based colors.
Loading
To completely fill brush with color.
Luster
An overglaze that imparts an iridescent surface to the ware.
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M
Majolica Technique
Underglazes applied in design over an unfired nonmoving glaze. After the glaze firing, the design is a permanent part of the glaze surface.
Mask ‘n Peel®
Trade name of water-soluble emulsion used to protect design areas on greenware or bisque. Must be removed before firing. Can also be used with nonfired colors.
Maturing Point
Temperature needed to mature glaze or clay.
Mending
Repairing broken greenware or bisque.
Modeling Clay
Prepared clay for hand modeling.
Mold
A hollow plater-of-paris form in which articles are reproduced through the use of liquid clay (slip).
Mold Keys
Matching parts on each mold section that align mold properly for casting.
Muffle
Heat-conducting pieces of pipe around firing chamber of gas kiln.
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N
Nichrome
A heat-resistant type of wire.
No-Fire Snow
Trade name of a nontoxic product that creates realistic snow effects without firing.
Nonmoving Glazes
Glazes that move or flow very little in the glaze firing.
Nontoxic
Refers to a ceramic product that conforms to the US standard ASTM D-4236 and is certified to contain no materials in sufficient quantities to be toxic or injurious to humans or to cause acute or chronic heal problems.
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O
Oil Based Translucent Stains
Trade name of oil-based antiquing translucents that are wiped back with water.
Opaque
Nontransparent color.
Overglaze
A decorative finish applied over a fired glaze surface and made permanent by firing.
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P
Palette Knife
A flexible knife with no sharp point used for mixing, stirring, and applying color.
Pat
Gently touching color to desired areas of ware with brush, sponge or cloth, in an up-and-down motion.
Patch-A-Tatch®
Trade name of a mender for welding broken greenware or bisque.
Pinholes
Tiny holes penetrating a glazed surface. A glaze defect caused by underfired bisque, applying glaze to greenware, firing too rapidly or poorly deflocculated casting slip.
Plasticity
Pliability of modeling clay.
Pooling or Puddling
Fired glaze that has run to the bottom or puddle in detail of ware.
Porcelain
A vitrified clay body that matures at a high temperature and is translucent.
Porosity
The permeability of fired or unfired clay.
Posts
Columns of refractory material used to support shelves inside the kiln. See Furniture, Kiln.
Potter’s Wheel
Revolving wheel driven by foot or electric power, used in forming articles from clay.
Pottery
Articles formed from clay.
Pouncing
Applying color to ware with quick up-and-down movements, using a brush or a sponge.
Pouring
See Casting
Pouring Sprue
A term for the excess clay around a mold’s pour hole that is trimmed away before opening mold. See Spare.
Pyrometer
An instrument that indicates temperature in the kiln.
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Q
Quick-Crackle™
A nontoxic water-soluble medium used to create an antique wood or aged pottery effect.
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R
Red-Coats®
Trade name of opaque underglazes in intense reds.
Refractory
Heat-resistant material.
Rolling Consistency-
Consistency to which glazes are thinned for rolling inside ware: milk consistency for 2-coat glazes; light-cream consistency for 3-coat glazes; cream consistency for 4-coat glazes.
Rolling Glaze
Method of covering inside area of ware, by rolling thinned glaze inside, then pouring out excess.
Running
Refers to fluidity of a glaze at the point of maturity before cooling and hardening.
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S
Safety Timer
A back-up shut-off device designed to turn the kiln off if the automatic shut-off device fails to do so.
Satin Glazes
Trade name of nontoxic glazes that produce a smooth, opaque matte finish and move very little in the firing.
Score
To scratch tiny crisscross lines on areas of greenware that will be fastened together with Duncan Patch-A-Tatch® or clay slip.
Scrubbing
Applying an initial priming coat of thinned opaque underglaze or glaze, or partially removing fired metallic overglaze from ware.
Sealers
Spray or brush-on coatings for use over nonfired colors to protect the surface and enhance the colors.
Seam
Ridge formed in greenware where mold pieces join.
Seep
The leaking of fluids through fine cracks or openings.
Sgraffito
A method of creating a design by gently scratching through applied color to reveal the color of the clay body beneath it or to create carved designs.
Shelf Support
Same as posts. See Furniture, Kiln.
Shelves
Flat Slabs of special high-temperature materials on which ware is placed inside kilns. See Furniture, Kiln.
Shivering
Occurs when the glaze or underglaze and the clay body or incompatible. The clay body shrinks more than the color, causing the color to peel or break away from the body after firing.
Shrinkage
Reduction in size of a clay object as a result of firing.
Signature Brushes
Trade name of Duncan red sable or badger hair brushes designed specifically for use on ceramics.
Silk Sponge
For decorating; recognizable by short hairs over entire sponge. Soft when wet.
Slip
Clay in liquid form.
Slip Trailing
Using slip in an applicator bottle to flow on design for a raised effect. Tinting slip can be used for contrasting details.
Smoking
Greying or discoloration of a glaze, caused by underfiring.
Snow
A special effect glaze formulated to create snow and fur effects.
Snow Accents
Trade name of a nontoxic product that creates realistic snow effects without firing.
Soaking
Holding the temperature in the kiln chamber for a longer period of time than usual.
Soft Bisque
Ware that has been fired to witness cone 06-05.
Solvent
A dissolving agent used in antiquing and to clean brushes used with oil-based translucent colors.
Spare
A term for the excess clay around a mold’s pour hole that is trimmed away before opening the mold. See Pouring Sprue.
Sparklers Brush-On Glitter
Trade name of nontoxic nonfired premixed glitter colors.
Spattering
Method of applying small flecks of color to ware, usually with a bristle brush.
Sponging
Use of sponge instead of brush to apply colors directly to the surface of the ware or over a base coat.
Spray Sealers
Non-fired final spray coatings that produce smooth, hard surfaces.
Stagger
To separate successive coats of glaze by fractions of an inch to prevent glazes from flowing together or from dripping off base of ware in firing.
Stencil
Paper perforated with a design through which color can be brushed or sponged onto a surface.
Stick Ons
Greenware parts added to main casting (ex. handles to cups). See Add-Ons.
Stilts
Supports used to separate a glazed article from a shelf during firing. See Furniture, Kiln.
Stippling
A method of applying color by pouncing the tip of a brush loaded with color against the ware.
Stoneware
A heavily grogged clay body requiring a high firing to vitrify.
Suspension Agent
Chemical added to keep glaze ingredients from separating.
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T
Template
A pattern or guide used in shaping a clay form.
Terra Cotta
Natural low-fired clay. Also a color.
Texture
Planned surface finish or roughness produced for interest.
Thermal Shock
Subjecting the ware to abrupt changes from hot to cold or vice-versa.
Tint
To lightly apply diluted colors over a base coat or coloring a product with another product.
Tipping
Touching the tip of a loaded brush with other colors for a muted shading or accenting.
Translucent
Transparent, allowing color underneath to show.
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U
Ultra Metallics™
Trade name for nontoxic nonfired water-based metallic colors.
Underglaze
A ceramic color used under a glaze.
Utility Items
Dinnerware, cups, canister sets, lamps – functional rather than purely decorative items.
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V
Vent Holes
Small holes made by piercing greenware when attachments have been made to allow trapped gases and moisture to escape from attachments during bisque firing.
Viscosity
Rate of resistance to flow.
Vitreous
Impervious surface (waterproof).
Vitrify
To become a stone-hard impervious surface.
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W
Wash
Color and water solution, used for shading and antiquing.
Water Smoking
The first part of firing, during which moisture is forced from the clay.
Water-Based Antiquing Gels
Nontoxic nonfired water-based colors for antiquing over all Duncan nonfired colors.
Waterproof
See Impervious
Wax Resist
A wax emulsion that repels underglazes and glazes applied over it. The wax is burned off in the firing.
Wedge
To force air pockets and bubbles from modeling clay by rolling it back and forth and from side to side on a flat surface, applying hand pressure at the same time. Studios often use a professional wedging table equipped with a wire for cutting the clay to release air bubbles.
Welding
Sealing two clay surfaces together.
Wheel
See Potter's Wheel
Witness Cone
Cone placed on kiln shelf to check the firing accuracy. Due to heat rising, one should place a witness cone on each shelf to measure the consistency of heat throughout the kiln.
Wool Sponge (or Sea Wool Sponge)
Very open texture and soft when wet.
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