Leather-Hard Decoration Techniques
Most surface decoration happens at the leather-hard stage — when the clay is firm enough to handle but soft enough to carve. Timing matters enormously. Too wet and the clay deforms under your tools. Too dry and it cracks or chips. Stephen Jepson describes the perfect moment as when the clay feels like cold butter — it holds its shape but yields to pressure.
Slip Trailing
Slip trailing applies liquid clay through a squeeze bottle to create raised lines, dots, and patterns on the surface. Think of it as cake decorating with clay. The slip sits on top in a slightly raised profile, catching light and glaze differently than the surrounding surface. Use a thick, yogurt-consistency slip for clean lines.
Sgraffito
Apply a contrasting layer of slip or underglaze, let it dry to leather-hard, then scratch your design through it to reveal the clay body beneath. The contrast between the colored surface and the exposed clay creates bold, graphic patterns. Use a needle tool for fine lines or a loop tool for broader strokes.
Mishima — The Inlay Technique
Mishima reverses the sgraffito approach. Carve your design into leather-hard clay, then fill the carved lines with contrasting slip. Let it set up, then scrape the surface clean so slip remains only in the grooves. The result is precise, inlaid lines — a technique with roots in Korean ceramics dating back centuries.
Bisque-Stage Decoration
Underglaze Painting
Underglazes are colored ceramic pigments applied before the final glaze. They stay exactly where you paint them, giving you precise color control. Paint on leather-hard clay or on bisqueware — both work. Layer colors, blend gradients, or paint detailed images. Cover with a clear glaze to seal and brighten the colors.
Wax Resist
Apply liquid wax to areas you want to remain unglazed or to keep one glaze from overlapping another. The wax burns away in the kiln, leaving clean divisions between glazed and unglazed surfaces. Creates striking two-tone effects and exposes the beauty of the bare clay body.
Oxide Wash
Mix metal oxides — iron, cobalt, copper, manganese — with water and brush over textured surfaces. Wipe the high points clean while the oxide settles into the recesses, highlighting carved or stamped details. A simple way to add depth and age to your work.
Carving and Stamping
Carving removes clay to create recessed patterns — from simple lines to intricate floral designs. Stamping presses patterns into the surface using found objects, commercial stamps, or hand-carved tools. Both must be done at leather-hard stage. Stephen Jepson often combines carving with oxide washes for pieces that have remarkable depth and texture.
When to Apply Each Technique
- Wet clay — Texturing with tools, finger marks, impressing objects
- Leather-hard — Carving, stamping, sgraffito, mishima, slip trailing, coil attachment
- Bone dry — Very light sanding only, no decoration (too fragile)
- Bisque-fired — Underglaze painting, oxide washes, wax resist, glazing