Trimmed feet on pottery gives a nice visual lift and a certain elegance to many pottery forms. The decision to give a pot a trimmed foot must be made before the form is thrown, however, in order to ensure that there is enough clay in the pot's floor to allow for trimming.
The object in trimming is for the pot's outer surface to mirror the inner surface. The pot's walls and floor should be even in thickness, except for the foot ring itself.
The pot is ready to trim when it has reached medium leather hard. If the clay is too soft, it will clump; if it is too hard, the clay won't cut well and may chatter. Before re-centering the pot on the wheel, check the pot's walls and floor curvature and thickness.