Aardvark
A national supplier of clay and ceramic materials.
- Address: 1400 E Pomona St, Santa Ana, CA 92705
- Phone: (714) 541-4157
- Supplies: Bee Mix, Bee Mix with Sand, Rod’s Bod, Rio Red, Black Mountain, Coleman Porcelain.
Bat
A circular disk used on the wheel as a work surface for throwing.
- Held in place by bat pins, clay, or synthetic materials.
- Allows easy removal of work from the wheel.
- Plates and large bowls benefit most from bats.
Bisque
The first firing of pottery before glazing.
- Our studio bisque fires to Cone 06.
- Porous surface allows glaze to adhere.
Blistering
A glaze defect where bubbles rise and break, leaving sharp edges.
Bloating
Air “blisters” or raised bumps on the clay surface, usually during firing.
Bone Dry
The driest stage of greenware, with all moisture evaporated.
- Ready for bisque firing.
- Very fragile — can break easily.
- Small defects may be lightly sanded with ScotchBrite pads.
Break (of glaze)
The effect of glaze appearing lighter/thinner on edges and texture, showing variation in color.
- Examples: WooWoo Blue, Tenmoku.
Burnishing
Polishing greenware with a smooth tool (stone, spoon, etc.) to create a shiny surface without glaze.
Calipers
Adjustable measuring tools for inside and outside diameters.
- Double-ended; one end measures internal, the other external.
Celadon
A transparent glaze that allows surface decoration to show through.
- Studio uses KW Celadon and Coleman Blue Celadon.
- Works best on light clay bodies.
Centering
The first step in throwing clay on the wheel, shaping it into a symmetrical mound.
Chuck
A bisqued cylinder used to hold unevenly shaped pieces for trimming.
- Centered on the wheel, with the pot placed inside.
- Temporary chucks can be made from fresh clay.
Clay
Naturally occurring soil composed of fine particles that give it plasticity.
- Provides elasticity and moldability.
Clay Body
A formulated mix of clays and other materials designed for specific uses (functional, sculptural, etc.).
- Varies in color (white porcelain to dark stoneware) and texture.
Closed Form
A fully enclosed clay shape (balloon-like).
- Requires a small vent hole before firing to release air.
- Can be sealed with glaze afterward.
Compression
Pressing clay to align platelets and strengthen the structure.
- Wheel: achieved with ribs/fingers across the base to avoid cracks.
- Slab/coil: requires thorough compression to prevent S-cracks.
Cone
Pyrometric cones measure kiln temperature by bending at specific heat levels.
- Cone 06 = bisque.
- Cone 10 = glaze.
Cookie
Clay disks (approx. ¼” thick) placed under pots during glaze firing.
- Protect kiln shelves from glaze drips.
Crawling
A glaze defect where glaze pulls away, leaving bare spots.
- Usually caused by dirt, dust, or oil on the bisque surface.
Crazing
Fine cracks in fired glaze.
- Considered a defect in functional ware (can harbor bacteria).
- In raku, it is often valued for decorative effect.
Earthenware
Low-fired pottery, often porous unless glazed.
- Traditional terracotta is earthenware.
- Historically widespread (Egypt, Greece, Rome, China).
- Softer and less durable than stoneware or porcelain.
⚠️ Note: Our studio does not use earthenware — we fire only to Cone 10 stoneware.
Faceting
Cutting straight surfaces (facets) into clay forms, usually on thrown or handbuilt work, to create texture and angles.
Flameware
Clay formulated to withstand direct heat from stovetops.
- Rarely used; not available in our studio.
- Regular stoneware is oven-safe, but not stovetop-safe.
Fluting
A decorative technique using vertical grooves carved into a piece.
Greenware
Any unfired clay object.
- Stages: Wet → Soft Leatherhard → Leatherhard → Firm Leatherhard → Bone Dry.
- Fragile at all stages; must be handled carefully.
Glaze
A liquid suspension of minerals that becomes glass-like when fired.
- Makes pottery waterproof and decorative.
- Cone 10 glazes vitrify completely → durable and food safe.
- Raku glazes do not vitrify → remain porous.
Glaze Firing
The firing that matures glaze and clay into a vitrified surface.
- May be glossy, satin, or matte.
- Cone temperature depends on clay body and glaze used.
High Fire
Refers to clays and glazes fired to Cone 8–10 (approx. 2,234–2,381 °F).
- Produces vitrified, durable, oven- and dishwasher-safe pottery.
- Our studio uses Cone 10 clays and glazes, fired in reduction.
Kiln
A high-temperature oven for firing clay.
- Types: electric, gas, wood.
- Our studio uses gas kilns.
- Raku kilns are a special subset for rapid firing.
Laguna Clay
Supplier of clays we use: Amador, Dark Brown, Long Beach, B-Mix, WSO, Stony White, English Porcelain, Dave’s Porcelain, Max’s Paper Clay.
- Located in City of Industry, eastern LA County.
Leatherhard
Clay that has stiffened but still contains some moisture.
- Best stage for trimming, carving, and attaching handles.
Low Fire
Clays and glazes fired to Cone 06–04 (approx. 1,830–1,940 °F).
- Not used in our studio — we fire Cone 10.
Luster (Overglaze)
A metallic finish (like gold or mother-of-pearl) applied over glaze.
- Fired at a very low temperature (Cone 022–017).
- Adds decorative shine.
Mason Stain
Commercial stains made of encapsulated pigments.
- Can be added to slip, glaze, or clay.
- Used to create a wide range of stable colors.
Memory
The tendency of clay to “remember” its earlier shape.
- Can cause distortion if clay was stretched unevenly.
- More noticeable in porcelain.
Mid-Range
Refers to Cone 4–6 firings (approx. 2,150–2,230 °F).
- Sometimes called “high fire” in other studios relative to bisque.
- More accurately described as mid-range.
Mishima
An inlay technique: carve lines into clay, fill them with contrasting slip or glaze, then wipe the surface clean.
Mold
Forms used to shape clay.
- Hump mold: clay draped over the mold.
- Slump mold: clay pressed inside the mold.
- Often made of plaster to absorb water from clay.
Oxidation
A firing atmosphere with plenty of oxygen.
- Produces bright, predictable glaze colors.
- Electric kilns = oxidation by default.
Oxide
Metallic compounds used as colorants in glazes, slips, or underglazes.
- Examples: iron, cobalt, copper, manganese.
- Can be applied as washes or stains.
- Only oxides under glaze are food safe.
Pinholing
Tiny holes in fired glaze caused by escaping gases.
- May result from thick glaze application or insufficient firing.
- Prevented by careful glazing and firing schedules.
Plaster
Used for molds, bats, and wedging tables because it absorbs water.
- Clay releases easily from plaster molds.
⚠️ Never use metal tools on plaster — particles contaminate clay.
Plasticity
The quality of clay that allows it to be shaped and hold form.
- High plasticity = easy to shape.
- Low plasticity = more difficult to form.
Porcelain
A fine, white clay body that vitrifies at high fire.
- Extremely strong once fired.
- Can be translucent when thin.
- Delicate to work with in raw form.
Quartz Inversion
A critical change in the crystalline structure of quartz within clay at ~1,063 °F.
- Causes expansion and contraction.
- Kilns must be fired slowly through this stage to avoid cracking.
Reduction
A firing atmosphere with limited oxygen.
- Produces unique, variable glaze effects (copper reds, celadon greens, shino oranges).
- Our Cone 10 glaze firings are all done in reduction.
Resist
A material applied to bisque or greenware to block glaze.
- Common types: wax resist, tape, latex.
- Burns off in firing, leaving unglazed areas.
Rib
A flat tool used for shaping, smoothing, and compressing clay.
- Materials: wood, metal, rubber, silicone, plastic.
- Can be flat, serrated, curved, or flexible.
Rutile
A mineral (titanium dioxide with iron oxide) used in glazes.
- Creates streaking, mottling, and warm golden tones.
- Key ingredient in rutile blue glazes.
S-Cracks
Cracks that form in the base of thrown pots from poor compression or uneven drying.
Scoring
Scratching lines into clay surfaces to help them bond when joined with slip or water.
Sgraffito
Decorative carving through a layer of slip or underglaze to reveal the clay body beneath.
Shrinkage
The reduction in clay size during drying and firing.
- Most clays shrink 10–15%.
- Important to account for in design.
Slip
Liquid clay used for decoration, casting, or joining pieces.
- Can be colored with stains or oxides.
- Casting slip used in plaster molds.
Slipcasting
Pouring liquid clay (slip) into plaster molds.
- The plaster absorbs water, forming a clay shell.
- Common in commercial production.
Stain
Prepared colorant mixture applied to bisque ware before glazing.
- Must be covered with glaze (often transparent).
- Dry stains require masks and ventilation.
Stoneware
Durable, vitreous clay body fired to high temperatures (Cone 10).
- Less refined than porcelain, but stronger during handling.
- Excellent for functional ware.
Tenmoku
A traditional dark, glossy glaze originating in China.
- Colors range from black to deep brown, with reddish or rust highlights.
Thermal Shock
Stress caused by sudden temperature changes.
- Can cause pots to crack or break.
- Example: moving a hot pot directly into a cold environment.
Trimming
Removing excess clay at the leatherhard stage.
- Wheel-thrown pots are inverted and refined with trimming tools.
Underglaze
A liquid colorant applied to greenware or bisque before glazing.
- Brands in our studio: Coyote, Amaco Velvet, Stroke & Coat.
Vitrification
The process of firing clay until it becomes glass-like and non-porous.
- Stoneware (Cone 10) is vitrified.
- Porcelain reaches near-zero porosity.
Warping
Deformation of clay during drying or firing.
- Caused by uneven thickness, poor support, or overfiring.
- Porcelain is especially prone to warping.
Wax Resist
Wax applied to clay to block glaze or decoration.
- Burns off during firing.
- Commonly used to keep glaze off the bottom of pots.
Wedging
Kneading clay to remove air pockets and align particles.
- Ensures even consistency.
- Bagged clay often requires little or no wedging.