Sculpture Terminology: 50 Terms Every Artist Should Know

March 26, 2026

Reference Guide

Sculpture Terminology 50 Terms Every Artist Should Know

From armature to waste mold — the complete working vocabulary of sculpture, explained in plain language with links to the materials behind each term.

Sculpture Depot|Reference|Updated 2026

Sculpture has its own language. Walk into a foundry, a studio workshop, or a sculptor's critique and you'll hear terminology that doesn't appear in everyday conversation — and rarely gets explained clearly. This glossary fixes that.

Every term below is defined in the context of how working sculptors actually use it. Where a term connects to a specific material or tool, we've linked directly to the product. Use the search bar and category filters to find what you need quickly.

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Showing 50 of 50 terms

Additive Sculpture Structure

A sculptural method where material is built up to create form — adding clay, wax, or plaster to an armature. The opposite of subtractive sculpture (carving). Most figurative clay and wax work is additive.

Almaloy Wire Material

A non-staining aluminum alloy wire used for building armatures. Softer and more pliable than standard aluminum, it bends easily without springing back and won't discolor oil-based clays.

Armature Structure

The internal skeleton of a sculpture — wire, steel rod, wood, or a combination — that supports the clay or wax from within. Every figurative sculpture larger than a few inches requires one. Sculpture Depot carries wire armatures, TruForm anatomical armatures, and figure armature systems.

Armature Stand Structure

A freestanding metal base with a vertical rod and horizontal crossbar that holds an armature at working height. Offers 360° rotation. The Adjustable Armature Stand ($69.95) supports up to 75 lbs at 45°.

Backiron Structure

An L-shaped or T-shaped steel support that bolts to a baseboard and holds a figure armature upright. Bears the clay weight through a rigid vertical all-thread rod. Available in 16", 18", 24", and 28" sizes.

Baseboard Structure

The flat board (typically 3/4" melamine or plywood) that serves as the sculpture's foundation. The backiron bolts through it; the board sits on a sculpting stand or table. TruForm systems include a pre-drilled 11.5" × 20" white melamine baseboard.

Blocking In Technique

The initial stage of sculpting where large masses of clay are applied to the armature to establish the major forms — torso, head, limbs — without detail. Proportions and gesture are set during blocking in; detail comes later.

Brush-Up Mold Mold Making

A mold made by brushing liquid rubber (silicone or polyurethane) directly onto the sculpture surface in thin coats. Produces the most accurate surface reproduction. Requires a rigid mother mold over the flexible rubber. See silicone rubbers and polyurethane rubbers.

Casting Technique

Pouring a liquid material (bronze, resin, plaster, wax) into a mold to produce a reproduction of the original sculpture. The sculpture is created first in clay or wax, then molded, then cast. See polyurethane resins.

Chasing Technique

Cleaning, repairing, and refining a wax or metal casting — removing seam lines, patching bubbles, and restoring surface detail. Wax chasing uses heated irons and hand tools. Metal chasing uses pneumatic chisels and grinders.

Contrapposto Anatomy

An asymmetrical standing pose where the figure's weight rests primarily on one leg, causing the hips and shoulders to tilt in opposite directions. Creates natural, dynamic posture. One of the most important concepts in figurative sculpture.

Creep Technique

The slow, gradual deformation of clay under sustained gravity load over days or weeks. Creep causes sculptures to lean, sag, or slump — especially in warm studios. Prevented by proper backiron support and adequate armature wire gauge.

Draft Mold Making

The angle or taper built into a mold to allow the casting to release cleanly. Surfaces perpendicular to the parting line create zero-draft undercuts that lock the casting in the mold. Good mold design eliminates zero-draft situations.

Demold Mold Making

The process of separating the mold from the original sculpture, or removing a casting from its mold. Proper release agents are essential — without them, the mold bonds permanently to the sculpture.

Écorché Anatomy

A figure shown without skin, revealing the musculature and skeletal structure beneath. Écorché figures are essential study tools for understanding how muscles create surface form. Available as anatomical reference models.

Enlarging Technique

Scaling a small maquette up to a larger finished sculpture using proportional measurements (calipers, pointing machines, or grid systems). The maquette establishes the composition; the enlargement refines the anatomy and detail at full scale.

Flashing Mold Making

Thin fins of material that form along the mold's parting line during casting. Flashing must be removed during chasing. On wax, it's cut with wax cutting tools; on bronze, it's ground smooth.

Forton MG Material

A gypsum-based casting material reinforced with fiberglass for high strength and low weight. Used for making rigid mother molds and durable castings. Available at Sculpture Depot.

Foundry Finishing

A facility that casts sculpture in metal — typically bronze — using the lost-wax process. The sculptor delivers a finished wax (or the foundry pulls one from a mold), then the foundry handles investing, burnout, pouring, chasing, and patina application.

Gesture Technique

The dynamic energy, movement, and flow of a figure's pose — the overall sense of action captured in the sculpture. Gesture is established during blocking in, before any anatomical detail. A sculpture with strong gesture feels alive; one without it feels stiff.

Gate Mold Making

The channel in a mold through which liquid casting material enters. Gate placement determines flow patterns and where air can escape. In lost-wax bronze casting, gates are built from sprue wax.

Hollow Casting Technique

Producing a casting with hollow walls rather than solid fill. Reduces weight, material cost, and (in bronze) metal shrinkage. Wax castings are slush-cast hollow using casting wax; bronze is cast over a ceramic core.

Investment Mold Making

The heat-resistant ceramic shell or slurry mold built around a wax sculpture for lost-wax casting. The wax is burned out ("lost"), leaving a negative cavity. Molten bronze fills the cavity. The ceramic is then broken away to reveal the bronze casting.

Keys Mold Making

Registration bumps or notches built into a mold's parting line that ensure the mold halves align perfectly when reassembled. Made from plastic key nibs or cut into clay walls during the mold-making process.

Lost-Wax Casting Technique

The process of creating a metal casting from a wax original: the wax is encased in investment, the wax is burned out in a kiln, and molten metal fills the void. The dominant method for bronze sculpture for over 5,000 years.

Maquette Technique

A small-scale preliminary model (typically 6–12") created to work out composition, pose, and proportions before committing to a full-size sculpture. Maquettes are quick, expendable, and essential for planning monumental work.

Midline Anatomy

An imaginary vertical line running down the center of the figure from head to feet. Used as the primary reference for symmetry and balance. Sculptors mark the midline on the armature and check it continuously during modeling.

Mother Mold Mold Making

The rigid outer shell (plaster, fiberglass, or Forton) that supports a flexible rubber mold and maintains its shape during casting. Without a mother mold, the rubber would distort under the weight of the casting material.

NSP (Non-Sulfur Plasteline) Material

A sulfur-free, professional sculpting clay compatible with silicone molding rubbers. Sulfur inhibits platinum-cure silicone, so NSP is required when molding with tin-free silicone. Available at Sculpture Depot.

Oil-Based Clay Material

Sculpting clay made with wax and oil binders that never dries out or hardens. Can be reworked indefinitely. Includes Chavant, Classic Clay, Le Beau Touché, and Castilene. The standard medium for figurative sculpture intended for molding.

Patina Finishing

A chemical surface treatment applied to bronze (or resin) sculpture that produces color — greens, browns, blacks, blues. Created by applying chemical patina solutions to heated metal. Protected with paste wax.

Parting Line Mold Making

The line where mold sections meet. Determines how the mold separates for casting removal. Visible as a seam on the casting — this seam is removed during chasing. Good parting line placement minimizes visible seams on the finished piece.

Plasteline (Plasticine) Material

A generic term for oil-based, non-drying modeling clay. Plasteline stays pliable at room temperature and can be softened with heat or hardened with cold. Common brands: Chavant NSP, Classic Clay, Le Beau Touché.

Plumb Line Anatomy

A weighted string held against a figure (live model or sculpture) to verify true vertical. Used to check balance — if the plumb line from the pit of the neck doesn't pass between the weight-bearing foot/feet, the figure will appear to fall.

Polyurethane Resin Material

A two-part liquid plastic that cures to a rigid, paintable solid. Used for casting reproductions from molds. Much lighter and cheaper than bronze. Available in various hardnesses at Sculpture Depot.

Premiere Bronze (Wax) Material

A dark brown microcrystalline sculpting wax from REMET, specifically formulated for hand-forming original wax sculptures. Pliable, non-sticky, holds detail. The standard for wax originals in fine art foundry work. Available here.

Release Agent Mold Making

A spray, brush-on, or wipe-on barrier applied to a surface before molding or casting to prevent the materials from bonding permanently. Critical for multi-piece molds. See release agents and barrier coats.

Rubber Mold Mold Making

A flexible mold made from silicone or polyurethane rubber. The flexibility allows the mold to stretch over undercuts that rigid molds can't release. The most common mold type for figurative sculpture.

Silicone Rubber Material

A flexible molding material that captures extreme surface detail and releases cleanly from most sculpting materials. Available in brush-on and pour grades. Platinum-cure silicone is incompatible with sulfur-containing clays. See silicone rubbers.

Slush Casting Technique

Pouring liquid casting wax into a mold, rotating to coat all surfaces, then pouring out the excess — producing a thin, hollow shell. The standard method for creating wax patterns for lost-wax bronze casting.

Sprue Mold Making

A wax rod that creates a channel in the investment for metal to flow through during casting. Built from extruded sprue wax and attached with sticky wax. Also called a runner or gate system.

Sticky Wax Material

A high-tack bonding wax used to attach wax sprues to wax sculptures during the lost-wax casting process. Low ash content ensures clean burnout in the kiln. Available as pastilles.

Subtractive Sculpture Technique

Creating form by removing material — carving stone, wood, or hardened plaster. The opposite of additive sculpture. The sculptor works from the outside in, revealing the form that exists within the block.

TruForm Armature Structure

A pre-built, proportionally accurate skeleton armature with articulating joints, scaled to an ideal 8-head figure. Available in 12", 18", 24", and 36" systems. Teaches anatomy while providing structural support. Reusable indefinitely.

Turning Point Anatomy

The point on a form where the surface turns away from the viewer — the boundary between the lit side and the shadow side. Sculptors define turning points to create readable form; without sharp turning points, surfaces look soft and undefined.

Undercut Mold Making

Any area of a sculpture that prevents a rigid mold from releasing in a straight pull — overhanging forms, deep recesses, hooked shapes. Flexible rubber molds stretch over undercuts; rigid molds require multi-piece construction to release them.

Vent Mold Making

A small channel in a mold that allows trapped air to escape as casting material fills the cavity. Without vents, air pockets create voids in the casting. Placed at the highest points of the mold cavity.

Waste Mold Mold Making

A plaster mold designed to produce a single casting — the mold is chipped away to release the casting and destroyed in the process. Used when only one reproduction is needed. Fast to make but irreversible.

Water-Based Clay Material

Natural clay (earthenware, stoneware) that uses water as its binder. Dries out if not covered; can be fired in a kiln. Distinct from oil-based clay, which never dries. Less common for figurative sculpture but used for ceramic sculpture and pottery.

Wax Chasing Technique

The process of cleaning and refining a cast wax for foundry work — removing seam lines, patching air bubbles, welding sections, and restoring surface detail. Requires heated irons, hand tools, and patch wax.