Ram pressing uses a porous mold mounted in a hydraulic press. Damp clay is placed in the mold and the press is closed. Molds can be made from wood, plaster, or other porous material.
A vacuum is drawn on the mold halve to withdraw water from the work.
After the desired dewatering and dwell period has passed, the bottom half of the mold is pressurized and the mold is opened. The vacuum on the top half retains the work on the punch side.
The top half of the mold is pressurized to eject the part off of the mold.