A process for mass producing simple shapes on a mechanized pottery wheel having a solid swinging arm with a template. For plates, a profile describing the outside shape of the ware is used to force the soft clay against a rotating plaster mold describing the inside shape. For vessel forms, the profile forms the inside shape. After drying against the plaster the clay shrinks and releases and can be removed from the mold and the process repeated. After removal, fixup generally needs to be done to smooth any irregularities on the surface that was against the mold.
A crock being jiggered by Jim Etzkorn in 2013 at the historic Medalta Potteries in Medicine Hat, Alberta.
Surface treatment affects glaze speck development in jiggered stoneware
Notice the inside of this large transparent glazed cone 6 stoneware bowl. There is a concentration of specks on one part because that area was sponged at the leather hard and dry stages to smooth surface problems that happened during the jiggering process. These specks are normally driven below the surface during forming.
Laminations in a jiggered bowl
These are not cracks. They do not go through to the inside. During forming the clay was folded over itself rather than compressed against the mold.