Brick

Of all building materials, brick carries an emotional resonance unlike any other. Our attraction to it must be primal, given that humans have been making brick since at least 7000 B.C., . rst with mud and sunshine and then, around 3000 B.C., by putting earthen clay in fiery kilns. Brick is beautiful. Brick is plastic. And, as we know, it lasts practically forever, hardened by the kiln's extreme heat against all but catastrophic insults.

Since the rise of the kiln and what is called “. re brick,” essentially little has changed in the way brick is made. At the Belden Brick Co., a maker of architectural brick based in Canton, Ohio, some production lines are automated on a grand scale and some brick is made by hand, but the recipe still involves a conspiracy of earth, air, . re, and water. The last big technical change at Belden Brick was to switch its kilns completely from coal to natural gas in 1974. “The changes in brick manufacturing in the past 100 years are not signi. cant as far as engineering goes,” says Brian Belden, the company's marketing director. “The differences now are about how to get the brick fired more quickly and efficiently.”

Brian Belden is one of seven family members running the company and is a great-great grandson of its founder, Henry S. Belden, who started the company in 1885. Today, Belden Brick has about 500 employees who make 230 million bricks a year in six plants (each plant makes its own unique types of brick). All the plants are set among the picturesque hills around Sugarcreek, about a half-hour south of Canton.

Belden Brick is located in north-central Ohio because it's where the company gets its main raw materials, shale and fire clay, which lie just beneath the earth's surface, anywhere from 10 to 100 feet down. The company owns 17 broad, shallow mines, or pits, on 3,000 acres around the region. Before any site is mined, Belden's staff geologist, Joe Angel, takes core samples of shale and clay from the ground back to his laboratory for firing in a test kiln (or “skut kiln”), examining them for color and shrinkage as well as for their carbon and sulfur content (in both cases, less is better).

In an active pit, drivers board huge mechanical shovels and gouge into the earthen walls. They load big chunks of clay and shale separately—the materials, found in successive or alternating layers of the pit, stay separated until ground nearly to dust— into 22-ton hauling trucks. The same drivers then take the trucks back to the plant, which receives about 33 truckloads a day.

Credit: Timothy Hursley

Credit: Timothy Hursley

Grinding and sifting are carried out behind closed doors, simply to contain the epic amounts of dust they create. The conveyor belts outside bring the materials to belts running along the roof ridge, which dump into one of nine bins the size of small cabins. These bins deliver the shale and clay to the grinders, where three wheels rotating in different directions reduce the material to a consistency “like talcum powder,” Belden says. The ground material moves by conveyor to a separate area for sifting. Overhead bins (b) steadily release it onto a series of canted sifting screens (c) that work by vibration— even the catwalks shake jarringly while the system runs. Various gauges of interchangeable screens achieve specific levels of fineness, set to the type of brick being made at a given time.

After sifting, the clay and shale are mixed together. Barium carbonate is added to the mix in measured amounts to prevent unsightly white “scumming” on the brick and to reduce efflorescence during the firing. Belden Brick also adds a mined powder called garnet as a coloring agent for dark red bricks. Once the mixture reaches the first of two large tubs, water is added. In the first tub and then in the second, large augers churn the material vigorously before a belt takes it to what is known as a batch feeder.

Credit: Timothy Hursley

From here, the rather stiff wet mixture becomes bricks in one of two ways: It is either molded (by machine or by hand), or it is extruded. Molded bricks are made en masse when the batch feeder's auger forces the mix down into an open mold box that has slid beneath it to make 10 or more bricks at once. A robotic wheel then turns the lot of them onto pallets that are then carried away to the next stage, the chamber dryer, by automated “finger cars,” which have multiple prongs to hold racks of “green,” or unfinished, brick.

Alternatively, the wet mix is set aside for the hand-molding operation, where three craftsmen take hunks of wet brick to make “loaves” (see opening photo on page 116) they press into individual wood molds for custom shapes such as water tables, radials, sloped bricks, and bullnoses. As on the mass-molding line, the custom-brick makers line the molds with sand, which helps loosen the brick out of the mold and gives it color. They make between 400 and 500 bricks a day, compared with the 100,000 molded en masse. Once the bricks move to the finger cars, they are taken to the chamber dryers, ranged down a dim corridor like a series of crypts, where they warm at 300 F for about 24 hours. The empty finger cars return to the molding area for more wet brick.

Belden makes about 75 percent of its brick by extrusion, a process in which the wet mixture first is pressed through a vacuum chamber to compress it and then is pushed out like Play-Doh (a) through a die (b) that shapes a running strand of brick of a specific length and depth (with or without the “core bridge,” a set of horizontal metal rods that creates the holes in the beds of some bricks). The strand moves forward to be cut by a harplike contraption (c) strung with wires that cut the brick to a programmed height. Off to the side of this setup are a series of cast-iron dies the size of car wheels that create different shapes of brick. The design of new or custom dies is the job of the three-person Shapes Department.

Credit: Timothy Hursley

Extruded brick, once it's cut and placed on a car, travels to what is called a tunnel dryer, which is heated to the same temperature as the chamber dryer. (However, extruded brick contains less water than molded brick, so it won't stick when pushed through the extrusion machine.) In either case, the bricks have been stacked exquisitely on their narrow edges in alternating directions to maximize air flow and enhance variation in their final color palette.

Credit: Timothy Hursley

Dried bricks head for the 400-foot-long kilns, of which there are three in this plant, one for molded and two for extruded brick (including the kiln shown below). At any given time, the kilns hold 39 carloads of bricks. They inch along to warm slowly to about 2,100 F at the kiln's center and then slowly cool as they move to the other end. They emerge from the kiln quite warm to the touch.

As the bricks are packaged in lots of 525, a carousel distributes them around to several packers at a time in a process called blending. “We do that to control percentages of various colors that go together in a shipment,” Belden says. “That way, a mason can pull them out one at a time” to ensure that the fabric of the wall—or walk—they're building will be uniform only in its rich variation, which is typically the desired result. Getting the brick out of the plant is easy: Trucks can pull right up to the plant, as can trains on a rail spur, to load the brick and carry it off to its destination, where it is likely to stay for several lifetimes.