One of the complications of throwing plates on bats, discs attached to the pottery wheel head, is removing the plate from the bat without cutting through the bottom of the plate. Traditionally, ceramists pull a wire stretched between two toggles to separate the clay from the bat. When the wire is long, as is needed for plates, the center of the wire tends to ride up making it cut in a shallow arch shape. The arch shape of the traveling wire can a hole through the enter plate. Watch the video for a solution. Afterwards, consider using canvas bats for other pieces too.
