The potter learns about the inside while shaping what everyone will see outside.

The hand inside the pot feels the wall thinning while the hand outside gives it a shape. Neither works alone, and the visible curve is decided largely by what is happening where nobody can see. Most making is like this: the public form is a report on private conditions that were being managed the whole time.

Where you are trying to improve how something appears, ask what is going on inside it. Fixing the surface without attending to the wall usually produces something that looks right and does not hold.