The Basics of Pottery Wheel Throwing
Making pottery on the wheel consists of a series of hand pressures against a mass of moist clay which rotates with the wheel head. Different hand positions shape and form the clay, transforming it into a sturdy, useful vessel. The straightsided cylinder is the basis for all wheel-thrown pottery forms.
A Step by Step Guide to Forming a Cylinder
1. Wedging the clay
The purpose of wedging the clay is to work all the air bubbles out and evenly distribute the moisture throughout the piece of clay. It’s done by pushing the clay over and over again on a wedging table, similar to kneading dough.
2. Centering the clay on the wheel
The first step to making a pot is centering the clay. Place the clay as close to the center of the wheel head as you can. Apply enough pressure with both hands working opposite of each other so that the clay begins to move. As you apply pressure the clay moves upward. Then by placing your right hand on top of the clay you press it downward. These steps may need to be repeated several times to bring it into center.
3. Flatten and check for thickness
Once the clay is centered, flatten it some, then press thumbs down in center of the clay to open it up, being careful to leave a thick bottom.
You can check the thickness of the bottom with a needle tool. For most pots, 1/4” is perfect.
4. Opening & compressing the pot
To open it up further, place fingers of both hands to the inside, pulling carefully towards you.
Next, compress the bottom with a wooden rib to strengthen the bottom. Without this step, the bottom could crack during the drying or firing process.
Apply pressure from both the inside and the outside as shown. This will prepare the walls for the pulling.
5. Pulling up the walls
Apply equal pressure by both middle fingers on the inside and the outside of the pot simultaneously, working opposite each other. Then hold the pressure and pull slowly upward. The wall will grow taller and thinner.
Continue to pull the walls until the thickness on the side is about 1/4”. Then place the rib against the outside of the clay wall . With your hand, gently press the clay into the rib. This will smooth and straighten the walls.
With a wooden knife, cut into the foot of the pot at an angle, trimming only 1/4” inward. With the needle tool, trim the top of the pot if necessary (if it is uneven). Then use a sponge to smooth the lip. Now you are ready to shape the vessel.
Shaping a Vessel
Once a cylindrical base is formed, it can be shaped into dozens of different types of useful vessels in accordance with the amount of clay originally placed on the wheel.
The shape of a vessel is largely determined by the purpose and function of the piece. Each vessel should be not only attractive but should serve its function well with its design.
For a vase, start the shaping process by reaching down into the vase to the bottom with one hand and, balancing the pressure on the outside with your other hand, pushing the clay outward to form a rounded base. Repeat until the lower part of the vase is the shape you desire.
Next, apply pressure to the outside of the neck of the vase, pushing the clay inward, thus narrowing the neck. Then flare the top part of the vase using an outward pressure.
Further shaping can done with a metal rib, which will flex to the shape of the pot. With the rib, you can create gentle, smooth curves. The rib will also smooth the walls of the pot, removing any fingertip ridges. Once your shaping is completed, the upper edge, or lip, can be compressed to form a sturdy rim.
Drying the Inside
Check the bottom of your vessel on the inside for any remaining water. While the wheel head is turning slowly, absorb any water with your sponge. If water is left inside, it will dissolve the clay and lead to cracking.
Once you a finish shaping your vessel, you must slice it off the wheel head. Holding the wire tool taut, slide it under the pot on the far side and pull it across the wheel head toward you. This will separate the clay from the metal head. If necessary, set the edge with you finger to re-center the lip and also to round it. Very carefully transfer the finished vessel to a small wooden bat and place it on the drying rack to dry to prepare it for firing.