The Technique Step by Step

Knowing why we score and slip is important. Knowing exactly how to do it is what keeps your work together.

Step-by-Step

1. Identify both surfaces that will meet.
2. Score surface A: Scratch a firm crosshatch pattern, about 1cm square.
3. Score surface B: Do the same on the matching surface.
4. Apply slip to surface A: Use a brush, your finger, or a small tool. You want a visible coat: not a flood, not a thin smear.
5. Press together firmly: Push the two pieces together with real pressure. Wiggle slightly to help the slip spread and the two surfaces mesh.
6. Blend the seam: Use a finger or wooden tool to blend clay from one piece into the other on any accessible side.

The Moisture Match Rule

The two pieces you are joining should be at roughly the same moisture level. Joining very wet clay to leather hard clay is risky. The wet piece will shrink more than the leather hard piece, cracking the join as they dry.

The Fix: If moisture levels do not match, wrap the drier piece in a damp cloth for 15 minutes before joining.

Common Mistakes

• Dry slip: If your slip has dried on the surface before you press, it acts as a barrier, not a bond. Apply slip just before joining.
• Not enough pressure: A gentle press is not enough. Press firmly and wiggle.
• Skipping one surface: Both surfaces need to be scored. One is never enough.

Premium Repair Strategy

If a join looks weak before bone dry:

• Re-open the seam carefully.
• Re-score both surfaces.
• Add fresh slip and re-press with firm pressure.
• Add a thin reinforcing coil and blend well.

Early repair is far easier than post-firing regret.

Pro Tip

After joining, run a thin coil of soft clay along the seam and blend it in. This is the single best thing you can do to guarantee a strong join, especially on the inside.

Keep Exploring

The moisture-matching rule exists because clay minerals shrink as water leaves the spaces between their plate-like layers. When two pieces at different moisture levels are joined, they shrink at different rates and the resulting stress fractures the bond. This is the same principle behind differential shrinkage cracking in engineering materials.