Tuesday, May 27, 2008

How To Center A Cylinder On A Potter's Wheel

Forming a cylinder while working with a potter's wheel is common. What many don't know is that it can be a test of sorts. When a potter can successfully through a cylinder, and find that it is perfectly centered and completely even in all proportions it is proof that the potter is ready to begin forming more difficult and special shapes. Also, throwing a simple cylinder is the first step to making many different types of pots and vases. To that end here are step by step instructions on how to correctly through a cylinder and check to see if it is even.

Things You’ll Need:
Potter's Wheel
Clay Ball
Stick Sponge
Sharp knife

Throwing The Cylinder
Step 1:
Slam a ball of clay hard down on the wet batt covering the head of the potter's wheel. This will add suction to the bottom of the clay and keep it attached to the batt.

Step 2:
Start the wheel slowly with your hands cupping the clay ball so that it is evenly rounded and shaped.

Step 3:
When the ball is centered, press downward with the thumbs to make a depression in the top.

Step 4:
Brace the left hand against the mound of clay and, resting the right hand on the left, press the fingers of the right hand down on the middle of the mound to enlarge the opening.

Step 5:
The opening should go down far enough to leave a 3/4 inch thickness at the bottom of the piece. If you can't tell, use a toothpick, press it all the way down in the center and measure how much of the toothpick comes up wet with clay on it. Don't worry about the hole, that will be covered as you continue to work the clay.

Step 6:
The clay is now shaped like a low squat bowl with a thick wall. Let the wall turn in your hands for a while with your left hand on the outside and the fingers of your right on the inside. They should be exerting almost not pressure at all.

Step 7:
For this next step, slow the wheel down slightly as we will be doing the Pull up technique. Put your right hand on the outside of the piece and your left hand on the inside, with the thumb of the left hand brace against the right wrist.

Step 8:
Press the clay between the index finger of the left hand and the first knuckle of your right. Bring your hands straight up. Your left thumb, braced against your right wrist, will help you keep your hands the same distance apart so that the wall of the cylinder will be even in thickness.

Step 9:
Repeat this process two or three times, each time making the wall thinner and higher.

Step 10:
keep the piece cylindrical. The top will have a tendency to become wider and turn the cylinder into a bowl, do not let this happen. Using both hands, pull the top together to keep it the same width as the base. Try to make the cylinder six inches tall, taller if possible, but six inches should be difficult enough.

Step 11:
The top edge of your cylinder will probably be uneven, so it will be necessary to trim off a narrow strip. Brace both hands in position and hold the left index finger against the inside of the rim while you press the point of the knife toward it from the outside.

Testing The Cylinder
Step 1:
With the finished cylinder before you and the wheel locked in place, put your knife on the top edge and cut straight down to the bottom. Then do the same thing to the other side.

Step 2:
Cut through the base and remove one half of the cylinder, so that you can look at the cross section. Is the wall even in thickness and only slightly heavier at the bottom? is it free from thin spots?

Step 3:
If not than you need more practice making cylinders before you can progress. If the cylinder is perfect, then congratulations are in order

Tips & Warnings
Remove the water that collects on the inside of the piece with a stick sponge. The fewer times you need to pull the piece upward, the lesser likelihood that the piece will collapse.

Use just enough water to keep the work lubricated, too much will cause the walls to weaken and slump. Remember you probably won't get this right the first time around, so don't be too hard on yourself.

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