Wedge Your Clay
Of all the steps you should do before sitting down to your wheel, wedging your clay is the most important one. Wedging helps compact your clay as well as getting air pockets out and ensuring the clay is uniform in stiffness.
Wedge your clay on a clean canvas or plaster surface. The kneading style of wedging also helps to align the clay particles. After you have fully wedged your clay, about 50 cuts or 50 kneading strokes, shape the clay into a smooth ball or oval.
Before sitting down to the wheel, be sure to place your tools and slurry or water bucket close at hand. I also recommend having a slop bucket close by for trimming scraps and pots that don't make it. Recommended tools are a potter's needle, a 2 x 3-inch piece of chamois, an all-purpose wooden trimming tool, and a cut-off wire.
Center the Clay on the Wheel
There are several ways to center clay on the potter's wheel. The following method is the one I have found works the best for most people I have taught.
Using medium force, smack the clay ball as close to the center of your wheel's bat as possible. Tuck your right elbow into the crease between your leg and torso or against the inner surface of your thigh. This keeps your wrist and hand steady; the clay can easily move just your hand. With the weight of your body acting as a brace, your wrist and hand can move the clay without having to fight.
Your wheel should be moving at full speed. Wet your clay with water or slurry. The clay should always be lubricated. If it dries out and grabs at your hands, the friction will cause the clay to go off center. Tuck the loaded sponge between your left palm and last two or three fingers. Squeeze liquid out as needed.
Using your braced right hand, push the clay inwards toward the center of the wheel head. Use your left hand to push the clay downwards. Feel free to push your clay up and down a few times. Some potters believe that this helps compact the clay even more and aids you during the throws.
The clay is centered when you can lay your finger or hand against it and the finger does not move in any way. Visually, it will look as if the clay were still, even when it is rotating at full speed.
Open the Clay and Form the Bottom
The next step is to open the clay on the wheel. While the clay is rotating at top speed and continually lubricated, lay your right thumb across the top (through the center axis). Push down on the end of your thumb with your left hand. Because your thumb is crossing the center, opening the clay this way ensures the opening will be centered as it is created.
Open the clay down to its final depth. You want to keep approximately half an inch of clay at the bottom of the opening. (Some of this will be lost when the pot is cut off the bat.) This forms the floor of your pot. If you aren't sure how thick the bottom is, then stop the wheel and use you potter's needle to measure it.
Reduce the wheel speed down to about half. Use your left hand to guide and brace your thumb. Pull your thumb outwards, keeping your right palm controlling the outer surface of the clay. Widen the opening to the size you would like for your pot's inner floor. Don't make the base too narrow. Keep in mind that you need to be able to move your hand up and down in the pot's interior.
Opening the clay is a fairly complicated process in itself. For more detailed instructions, see How to Open Clay.
Throw the Pot
Your wheel should be rotating at one-quarter to half speed. Again, you need to keep the clay continually lubricated.
Keeping the knuckle joint straight, bend both forefingers into a crook. Place your crooked right forefinger at the outer base of the pot, right up against the wheel. Your left forefinger goes on the inside wall, lightly resting on the floor of the pot. This automatically positions your hands for the throw: left forefinger raised above the right forefinger about half an inch.
Keeping your hands in tandem, move them straight upward. By doing this, you are thinning the walls and stretching them upwards. This action is the actual throw. If the clay tries to move outward, then slow your wheel speed.
Most pots take about three throws to thin the walls enough. Generally speaking, you should be aiming for a wall between a quarter and a half inch thick. To see more detail on how to throw (or pull up) the walls, go to the article, how to throw walls.
Compress the Rim
After the pot has been thrown, you need to do some finishing touches before cutting it from the wheel. First, use your sponge and soak up all liquid that has accumulated at the bottom of your pot. The liquid left in the pot will almost always cause cracking as the pot dries.
Soak your chamois in the water or slurry for a moment, until it is thoroughly saturated. With the wheel at about quarter speed, stretch the chamois across the rim, fingers against each side of the wall about a quarter inch from the rim's edge.
Push downward slightly on the chamois, without moving your fingers themselves downward. This will cause the clay to compress and form a bulge at the rim, which both strengthens it and is also visually pleasing. The chamois will also smooth the rim.
Lift up and away slowly.
Trim the Pot
Maintain the wheel at quarter speed. Use the wedge-shaped end of your wooden trimming tool on the outer bottom of the pot, removing the clay that your fingers couldn’t get under. Stop the wheel to cut through the trimmings, then gently rotate while lifting the trimmings away from the pot.
Do a final trim, producing a slight undercut at the bottom sixteenth to eighth of an inch. This undercut will give the pot a visual lift and finished look.
Cut the Pot Off the Wheel
Stretch your cutting wire as taut as possible across the far side of the bat. Start the wheel rotating very slowly. Keeping the wire flush to the bat’s surface and as taut as possible, bring the wire toward you in one slow, continuous motion. Stop the wheel and carefully remove the bat from the wheel head.
Place the bat somewhere out of harm’s way. When the pot is leather hard (approximately one to three days), then gently lift it from the bat and store it carefully. The pot will be ready for its bisque firing when it is bone-dry.