The main problem that results in ugly bottom is mostly wrong use of the hands while the lay is on the wheels. Most often, the clay has a tendency to spread out at the bottom but if they are being worked by expert hands, this is prevented from happening by the hands pushing in just enough to keep the clay from splaying. The right amount of collaring of the clay using the fingers will help ensure that the clay is not thicker at the bottom than at the top.
Avoid Pinching through the Walls
Pinch pots are common type of hand building pottery that is used to create what is known in pottery as pinch pots. The process of pinching pot involves using the thumb to press against the clay in a pinching motion. Since the process of creating pinch pots required molding with the hand, it can result in the potter pinching right through the wall of the clay. To avoid pinching through the walls of the clay, it’s important to avoid pinching to the required thickness using only one pinching movement. Rather carefully pinch the clay in a couple of movements until the desired thickness is reached.