History of Bricks
The history of bricks is a long and fascinating one. At Old World Bricks, we’ve compiled a brief overview so that you can learn how bricks were once made. At the turn of the century, brickmakers used a five-step process. This process created the timeless coloring that we love and made bricks as strong as steel and impervious to weather.
STEP 1: MINING THE CLAY
Because the steam shovel was not invented until 1879, early brickmakers dug for the clay on site with hand shovels. This was done in the fall. The early brickmaker chose his clay based on its color and texture and his own personal experience. He sought clay that was located just under the topsoil to minimize the work of digging with hand spades. The clay was then exposed to the weather, so winter’s freeze-thaw cycle could break down the clay and make it easier to be worked by hand. The elements made the clay soft and removed unwanted oxides.
STEP 2: PREPARING THE CLAY
In the spring, brickmakers could work the clay by hand. The clay was either ground into a powder and screened to remove stones, or placed into a soaking pit. Here, it was mixed with water to obtain the right consistency for moulding. The clay was then kneaded by hands and feet to thoroughly mix all the elements of the clay together. This step was called tempering or pugging and was the hardest work of all. In the mid-1800’s, horse-driven pug mills were invented to minimize the labor. At an opportune time, the clay was removed from the soaking pit or pug mill by a temperer, who then delivered it to the moulding table.
STEP 3: MOULDING
The assistant brick moulder (the “clot” moulder) would prepare a lump of clay and give it to the brick moulder. The brick moulder was the key to the operation and the head of the team. He would stand at the moulding table for twelve to fourteen hours a day and, with the help of his assistants, could make 3500 to 5000 bricks in a single day. He would take the clot of clay, roll it in sand, and “dash” it into the sanded mould. The clay was pressed into the mould by hand and the excess would be removed with a strike, which was a flat stick that had been soaking in water. This excess clay was returned to the clot moulder to be reformed. Sand was used to prevent the clay from sticking to the mould.
Single, double, four-, or six-brick moulds were used. The single brick mould had an advantage in that a child could carry it to the drying area. Beechwood was the preferred material for the mould for it was claimed that the clay would not stick to it. The top of the mould was laminated with iron to prevent wear. The brick slid easily out of the mould because it was sanded; these bricks are referred to as “sand struck bricks.” The process was also referred to as slop moulding.
The next person on the team was called an off-bearer. He would walk up to the moulding table, remove the filled mould, and take it to a drying area on a pallet or barrow. Here, the mould would be placed on a level bed of sand. He would then return the mould to the table and wet and sand it to receive the next brick.
STEP 4: DRYING
The moulded bricks were stacked in a herring bone pattern to dry in the air and the sun. They were left to dry for two days, at which time they were turned over to ensure uniform drying and to prevent warping. During this time, tools called dressers (or clappers) were used by “edgers” to straighten the bricks and obtain a smooth surface. After four days of dry, hot weather, the bricks were hard enough to be stacked in a herringbone pattern with a finger’s width between them for further drying. This area was called a hack or a hackstead, and the bricks were covered under a roof or with straw to protect them from the rain or harsh sun. After two weeks the bricks were ready to be burned.
STEP 5: BURNING
If fired bricks were on hand, they were used to construct the outer walls of the kiln and the surface was daubed with mud to contain the heat. If no fired bricks were available, the kiln was constructed entirely of green or raw bricks, which were stacked in such a way as to act as their own kiln. These kilns were called clamps or scove kilns. Wood and coal were used for fuel. Even after drying in air, the green bricks contained 9-15% water. For this reason, the fires were kept low for 24-48 hours to finish the drying process. During this time, steam could be seen coming from the top of the kiln. This was called “water smoke”. Once the gases cleared, brickmakers had to go-ahead to increase the intensity of the fires. If it was done too soon the steam created in the bricks would cause them to explode. Intense fires were maintained in the fire holes around the clock for a week until temperatures of 1800 degrees F were reached.
The knowledge and experience of the brickmaker dictated when the fireholes would be bricked over. At this point, the heat was allowed to slowly dissipate over the course of one week. When the kiln was disassembled, the sorting process began. If only raw bricks were used, the bricks from the outermost walls were kept to be burned again in the next kiln. Some bricks which were closest to the fire received a natural wood ash glaze from the sand that fell into the fires and became vaporized and deposited on the bricks. These bricks were used in the interior courses of the walls. Bricks that became severely over-burned and cracked or warped were called clinkers and were occasionally used for garden walls or garden paths. The best bricks were chosen for use on the exterior walls of the building. Those that were only slightly underfired had a salmon color and early bricklayers knew that the porosity of these bricks would help to insulate the structure and they were placed on the innermost courses of the wall.