Boston Valley Terra Cotta is the only ceramic manufacturer in the world utilizing 4 different forming methods in the manufacture of our architectural terra cotta products. These different processes give us the flexibility to create everything from flat TerraClad® rain screen panels to balusters for restoration of a Juliet balcony, all under one roof. When approached with a design, Boston Valley will consider the size, shape, ornamentation, finish, and individual piece quantity and select the best process for manufacture. Frequently, several of the processes below will be used on one project.

RAM Press

The RAM press is a hydraulic press originally used as a forming method in the porcelain industry. Pieces made with this forming method are not generally as sculptural as those made by hand pressing, however like hand pressing, this forming method does not allow for undercuts to be included in the die. The RAM die is a two part die made at Boston Valley to the approved shop drawing in the model and mold shop. A clay slug is placed on the die and hydraulically pressed into the form. Air forces water in the plaster die to the surface, releasing the piece from the mold.

Hand Press

This forming method is used for sculptural pieces, particularly ones that contain non-linear detailing or details with undercuts. The molds that are the negative of the finished piece are filled by hand with malleable clay. Rubber mallets are used to press the clay against all five faces of the mold to a set thickness. Internal webs are formed according to approved shop drawings and provide stability for the walls during drying and firing. Once pressed, the piece sits for a period. The plaster dehydrates the clay, allowing the piece to hold its form when released from the mold.

Extrusion

The extrusion forming method is most useful for the production of a linear directional profile that requires many units. This method of production utilizes a large extruder to force the clay through a steel die, forming a hollow cored unit. The profiles are extruded into lengths longer than the finished size required to account for the shrinkage during drying and firing. They are cut to a finished dimension in our sizing department after firing. Boston Valley has amassed a large catalogue of extrusion dies that can be used for new construction masonry projects.

Slip Cast

Slip casting utilizes a special recipe that produces a liquid clay body. This clay body is poured into a plaster mold and allowed to sit for a specified period of time. Again as in hand pressing, the plaster begins the dehydration process, drawing the water out of the liquid clay suspension and causing a measurable quantity of the solids to build up on the sides of the mold. Once the desired wall thickness of the finished piece is achieved, the extra liquid clay body is evacuated from the mold, and the piece is allowed to dry further before being released from the mold. This forming method is particularly suited for pieces with fine ornamentation and units that need to be hollow for anchoring such as balusters.