Once you are comfortable throwing cylinders, you may want to take on the challenge of throwing lidded jars. There are several types of thrown lids. Here we will discuss how to throw a basic inset-style lid.
In throwing lids, there are two main challenges. The first is to form the gallery flange. The second is to fit the lid and jar as closely as possible. This requires that you measure the jar and lid accurately, which is best accomplished with pottery calipers.
Begin by throwing a cylinder. As you complete each throw, leave a goodly section at the top that is thicker than usual. The actual amount you'll need to leave thickened will depend on the size of your pot, but it should be about one to three inches.
After the last throw to pull up the walls, finalize the lower portion of the jar into the form you desire. Clean up all liquid in the jar's floor and remove any excess clay from around the foot of the pot. Do not cut the pot free of the bat yet.
Working with clay you left at the top, support the wall on the outside with your right hand. The first two fingers on your left hand will be forming the flange of the gallery.
The upper finger should be placed at the rim and will press down and toward the right. At the same time, the lower finger be at the base of the bulge of clay and will pull upward on the excess clay. Since the two fingers are spread, with one and the top and one at the bottom of the excess clay, the excess will move into the gap forming the flange.
Keep the flange at about the same thickness as the main wall of the jar. You do not want the gallery flange to be too thin.