The Number One Rule of Handbuilding
If there is one rule you must never break in handbuilding, it is this: always score and slip before joining two pieces of clay.
Skip this step, and your pot will fall apart: in your hands, on the shelf, or explosively in the kiln.
What Is Scoring?
Scoring means scratching or roughening the surface of both clay pieces where they will meet. You can use:
- A serrated rib tool
- A fork
- A needle tool
- The edge of a credit card
Scratch a crosshatch pattern: lines going in two directions. This creates a rough surface with more area for the slip to grip.
What Is Slip?
Slip is clay diluted with water to the consistency of thick yogurt or sour cream. It acts as the glue between the two scored surfaces.
You can make slip by:
- Mixing scraps of the same clay with water and stirring.
- Letting a lump of clay soak in a small cup of water.
Always use the same clay body for your slip as for your pot. Different clay bodies shrink at different rates. A mismatch in shrinkage will crack your join during drying.
The Danger of Skipping
Fresh clay-to-clay joins may look fine when they are wet. The real damage happens during drying and firing, when the clay shrinks. Unscored joins peel apart. Slipless joins crack. Fired pots break along the seam.
Join Strength Checklist
A reliable join includes all four:
- Score both surfaces deeply enough to create texture.
- Apply fresh slip right before joining.
- Press firmly with slight wiggle to mesh surfaces.
- Compress and blend the seam after joining.
Miss one step and failure risk climbs fast.
Dig Deeper
Slip has been used as a bonding agent and decorative medium for thousands of years, from ancient Greek red-figure pottery to modern studio work. The crosshatch scoring pattern works because it increases the surface area available for adhesion, the same principle behind sandpaper roughening before gluing in woodworking.
