To make bricks from clay, there are traditionally five steps involved:
1. Obtaining the Clay
Making bricks in Minnesota in the late 1800s and early 1900s was a labor intensive process. Machines and automation were not in the picture yet. In the early brickyards, a shovel was the only way to dig clay. Of course, a good source of clay had to be found, and it helped to locate the clay source near an established transportation corridor. Damp or wet clay can be very heavy, so it is difficult to transport for long distances using man or horse power. Dried bricks are also heavy, and to transport large numbers of them, a railroad or river was extremely beneficial. Many clay deposits were found along the Minnesota River, and therefore the finished bricks could easily be transported by barge or boat into the Minneapolis/Saint Paul area. A railroad line was also built out to Chaska, Minnesota, which provided another means of transportation for the Chaska brickyards.
After being dug, the clay was aged over the winter. Brick making in Minnesota was a seasonal job, once winter arrived, operations essentially shut down. When the clay was exposed to the changing winter temperatures, it made the clay easier to work with. So each year, bricks were made from the past season’s clay.
2. Making the “Batter”
If you have ever dug clay and experimented with making bricks, you will find that clay is not always a uniform consistency. Sometimes small pebbles or rocks can get mixed in. The clay had to be screened or checked for these undesirable elements. The clay was also mixed with sand, which helped increase the strength of the bricks. I am unaware of what sort of clay-to-sand ratios the old brickyards used, but in some of the ones I have made, I have used about a 4 to 1 ratio.
3. Shaping the Raw Bricks
Once the raw ingredients were combined into the brick mixture, they had to be moulded into the proper shape for bricks. In the United States, most common bricks were made into a rectangular shape about 4 x 8 x 2 ¼ inches. Not that all the old Minnesota brick makers followed this standard, but they were close.
Balls or lumps of clay were “dusted” with sand and pushed into rectangular wooden forms. Any excess clay could easily be removed at this point. I have seen a Chaska brick mould which held about eight bricks in one solid frame. Again, if you have worked with damp or wet clay, you know how sticky it is. The sand dusting helps prevent the new clay brick from sticking to the sides of the mould.
4. Drying the Raw Bricks
After being formed, the new raw clay brick still had to be dried. A wet brick, if not handled properly, could easily be disfigured, rendering it useless. Rows of the new wet bricks were laid out in the sun or in special buildings to dry. These special buildings had stacks of shelves in them and a roof overhead to prevent rain from damaging the drying bricks. If you see old postcards or photographs of the brickyards, you can see rows and rows of these drying sheds.
Rain was an enemy to the early brick maker. If the rain was heavy enough, it could wipe out an entire batch of unprotected drying bricks. I researched a tornado that hit Grand Forks, North Dakota, on June 16, 1887. The heavy rain that occurred during the tornado destroyed thousands of drying bricks at the Grand Forks brickyard. Raw bricks would harden after several good days of drying, getting turned about midway through the process to ensure both the top and bottom sides dried out.
5. Firing the Bricks
The final step in the brick making process was cooking the bricks in special kilns. Many of these old kilns looked like beehives, which gave them their name, beehive kilns. These were rounded buildings that looked much like a ball cut in half. These kilns were made of special bricks, to keep the high temperatures needed for curing the bricks inside the kiln. The first brickyards used wood to fire the kilns, therefore it also helped to have the brickyard near a good source of wood. Once again, the Minnesota River valley was a good source of wood, so brickyards in this area were successful. Later on, brickyards transitioned to coal fires.
Thousands of raw bricks were stacked in the kilns prior to the burn. The circular shape of the kiln was not a random design, the circular shape helped keep the hot air circulating inside the kiln. Once the fires were started, the temperature was kept at a low heat for several days. This allowed any remaining moisture from the inside of the brick to dry out. Then the temperature of the fire was increased until it reached a very high point (1500 to 2000 degrees Fahrenheit). At this point, any remaining holes to feed the fire in the kiln were bricked over and the fire was allowed to burn out. The kiln was then left alone until it cooled off.
Once it was safe to go inside the kiln, the bricks could be removed for sale. However, despite their best efforts, burn temperatures were never equal. Bricks that were located closest to the fire turned out differently than those farther away. Too much heat could warp or crack a brick. Not enough heat could result in a brick having to be fired again. Heat variations could also change the natural color of a brick.