Potter's Wheel and Kiln Lab: Exploring Clay Behavior |…

Clay Throwing Dynamics

Pottery making begins with shaping a lump of clay on a spinning wheel. The dynamics at play here involve the balance between centrifugal force and friction, which determines whether the clay will hold its shape or collapse under the wheel’s motion. By adjusting the radius profile, one can control the distribution of forces acting on the clay, ensuring that it forms a stable vessel.

The simulation allows you to edit the clay's thickness and shape in real-time, providing insights into how these changes affect the final product. Understanding these principles is crucial for creating functional and aesthetically pleasing pottery.

Drying Shrinkage

Once shaped, the clay must be dried to remove excess water before firing. Drying shrinkage occurs as the moisture content decreases, causing the clay body to contract. This process can lead to cracks and structural weaknesses if not managed properly. The simulation models a 5-8% drying shrinkage rate, which is typical for most ceramic materials.

The model takes into account the diffusion of water molecules through the clay matrix, illustrating how moisture moves from wetter areas to drier ones until equilibrium is reached.

live demo · related simulation● LIVE

Firing Process

After drying, the pottery must be fired in a kiln at high temperatures to transform it into a durable ceramic. The firing process involves several stages, including heating up to the quartz inversion temperature (573°C), where silica polymorphs change, and cooling down again. The simulation models these thermal processes, showing how heat is conducted through the clay wall and how stresses develop due to uneven heating.

Understanding the firing process is essential for achieving desired properties such as strength, color, and texture in the final product.

Energy Balance and Thermal Stress

The simulation also models the energy balance within the kiln, showing how heat is distributed and conserved during firing. This includes conduction through the clay wall, which can lead to thermal gradients and resulting stresses that might cause cracking or deformation if not controlled.

By simulating these processes, one can optimize the firing schedule to minimize defects and ensure a successful transformation of raw clay into finished pottery.

Frequently asked questions

How does drying shrinkage affect the final shape of the pottery?

Drying shrinkage can cause the pottery to deform or crack if it is not dried uniformly. Uneven drying can lead to internal stresses that may result in a misshapen vessel once fired.

What role does heat conduction play during firing?

Heat conduction through the clay wall affects how temperature changes are distributed throughout the pottery, influencing its strength and integrity. Uneven heating can lead to thermal stresses that may cause cracking or deformation.

Why is quartz inversion important in the firing process?

Quartz inversion at 573°C marks a phase transition where silica polymorphs change, which can affect the density and strength of the fired pottery. Understanding this temperature point helps in controlling the quality of the final product.

Can the simulation predict potential defects during the firing process?

Yes, by modeling heat conduction and thermal stress, the simulation can help identify areas where thermal gradients may lead to cracking or deformation, allowing for adjustments in the firing schedule or technique to prevent such issues.

Try it live

Everything above runs in your browser — open Potter's Wheel and Kiln Lab: Clay Throwing, Drying Shrinkage and Firing and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.

▶ Open Potter's Wheel and Kiln Lab: Clay Throwing, Drying Shrinkage and Firing simulation