Clay shivering is a ceramic defect that occurs when the glaze applied to a clay surface does not properly adhere and contracts more than the clay during cooling, causing the glaze to crack, flake, or even detach from the underlying clay body.
Cause and Mechanism
Clay shivering is primarily caused by a mismatch in the coefficient of thermal expansion between the glaze and the clay body. If the glaze contracts more than the clay during the cooling phase of firing, it can exert tension on the clay surface, leading to cracking and detachment.
Types of Shivering
There are two main types of shivering:
- Hard Shivering: In this case, the glaze contracts so much that it creates significant stress on the clay, resulting in visible cracks or flakes in the glaze.
- Soft Shivering: Soft shivering is less severe and may result in subtle surface irregularities or small cracks in the glaze.
Prevention and Solutions
To prevent clay shivering, consider the following:
- Use glazes with compatible coefficients of thermal expansion to your clay body.
- Adjust firing schedules to promote better glaze-to-clay bonding.
- Test glaze-clay compatibility before applying glaze to larger pieces.
Understanding clay shivering and taking appropriate measures to ensure glaze-clay compatibility can help you create ceramics with durable and visually appealing finishes.