Molding

The brick industry in New Jersey typically used one of three methods of molding: the soft-mud process, stiff-mud process, or dry-press.

In the soft-mud process, the clay was mixed with water and pressed into wooden molds. The inner surfaces of the molds were sanded before being filled to keep the clay from sticking. The clay could be pressed into the molds manually or by a machine such as the Hand Operated Brick Press, Grand Automatic Brick Machine, or the Quaker Brick Machine. These machines usually had an upright box with a vertical shaft with rotating blades and a plunger that pushed the clay down into the press box. When the mold was filled, the extra clay was removed by an iron scraper.

The stiff-mud process used less water and involved the pressing of the clay through a rectangular die to shape the clay into a long rectangular shape, after which it was cut up into individual bricks. The machine (e.g., the Brick Extruding Machine and No. 3 Brick Machine) would typically have a cylinder with blades similar to a pug-mill, an auger to force the clay through the cylinder, and a die that would shape the clay into a rectangular bar of clay, which was then cut by a series of wires on a rack, a brick cutting machine, or an end-cut machine.

In New Jersey, the dry-press method was mostly limited to the production of front brick. In this method, the clay, either dry or semi dry, was pressed with great force by a dry press machine into steel molds. The molds were lubricated with steam to prevent the clay from sticking, and air holes were made in the dies to let air escape from the clay.

Many of the soft-mud and stiff-mud bricks to be used as front bricks were re-pressed to improve appearance, density, and strength. The re-pressing machines could be manually operated (producing as many as 3,000 bricks a day) or steam powered (producing as many as 25,000 bricks per day) (Ries and Kummel, 1904: 226-232).