We think of bricks as models of consistency, modular building units about 2 x 4 x 8, relatively identical in color. By the early 1900s, though, the distorted shapes and intense hues of clinker bricks, the manufacturing accidents that had long been the bane of brick makers, became a boon to creative builders and architects who found visual energy and natural beauty in the bricks' irregularity. While clinkers are the famous example, other unusual brick types, such as Roman and tapestry bricks, were just as popular around the turn of the 20th century. If your old house is made with one of these uncommon bricks, a little background on what they are and where they come from can help with future restoration or repair projects.
What Are Clinker Bricks?
Named for the distinctive sound they make when banged together, clinker bricks are the result of wet bricks placed too close to the fire. The intense heat of coal-burning traditional kilns created a hard, durable brick that often twisted into volcanic shapes and textures. Overbaking produced rich, warm colors as well that ran the gamut from reds, yellows and oranges to deep, flash-burned browns, purples and blacks. No two clinker bricks were alike, rendering them trash to brick manufacturers who prized uniformity, but treasure to early modern architects, builders, and homeowners seeking uncommon architectural detail.
"Clinker bricks were rejects because they were discolored or misshapen," explains John Gavin of Gavin Historical Bricks, an Iowa City-based supplier of reclaimed antique paving and building materials. "The bricks were, however, still a solid building material, and in the early 20th century clinkers became popular when avant-garde architects started building houses with them precisely because they were so unusual."
During the Arts & Crafts era, clinkers were used to accentuate bungalow architecture, creating visual interest in focal points such as chimneys, porch supports and garden walls. The use of clinkers in English walls during the 19th century was well documented, but Charles and Henry Greene, who incorporated clinkers in their most famous California houses, may have been impressed after seeing the bricks used in buildings near Boston, where both brothers attended MIT.
Clinker use spread to other architectural styles, too, especially Colonial Revivals along the East coast, where entire homes, not just chimneys, were made of them. Kingston Heath, director of the historic preservation graduate program at the University of Oregon, thinks clinkers appealed to Colonial Revival designers because their irregularities hearkened back to pre-industrial times.
A Scarce Resource
In these days of automated manufacturing, when perfectly identical bricks are produced thousands at a time, clinkers are all but nonexistent. Therefore, homeowners who seek these one-of-a-kind bricks for restoration or renovation projects have limited options.
Clinkers are available through a few salvage companies that reclaim and rescue bricks from demolition sites or discard piles. Gavin, for example, looks for clinkers at their original source. "We find the old, abandoned kilns where bricks were made," he says. "Then we see where [workers] threw away the clinkers." Gavin researches promising kiln sites through historical societies and does flyovers in airplanes before he starts digging. When demand for clinkers increased about five years ago, Gavin began manufacturing them using a painstaking process, which is somewhat ironic given that the originals were created by mistake.
"To be real clinkers, the bricks have to be made in beehive kilns, which are slow-baking," says Gavin. These large, round, brick edifices are sealed and coal-fired for weeks at a time. Gavin's clinkers are baked in 100-year-old kilns. To ensure the highest percentage of these specialty bricks, the kilns sustain temperatures of 1,850 degrees Fahrenheit for three weeks straight. Although the demand for authentic clinkers is small, there is a growing market from people who are traditionalists or "want something unique and beautiful," says Gavin.
Working with Clinkers
Using reclaimed or freshly minted bricks isn't the only way to handle a clinker brick restoration. When Hurricane Isabel tore through the mid-Atlantic in 2003, it dropped a tree through the sunroom of Susan and Mike Burnett's 1932 clinker brick Colonial Revival home in Norfolk, Virginia. Scratching their heads in front of the pile of rubble, they had a clinker of a dilemma. They knew they would rebuild but weren't sure if they had enough intact original bricks to do it with. So Susan came up with a solution: Make up the shortfall with modern bricks, color-matched to the clinkers, and blend the old with the new.
Susan knew that she could use all new bricks for the foundation, which was hidden by shrubs. For the two most visible areas of the reconstruction—the front of the house and one of the corners—she worked out a ratio that carefully proportioned the old brick to the new. Imparting this blended-brick vision to their mason was another story, however. "He didn't follow our instructions the first time," says Susan, "and he had to take it down and start over." After that, Mike kept a close eye on the day's progress.
When using new bricks to replicate the look of clinkers, the Burnetts recommend taking an original with you to the brickyard. Contemporary bricks can match the color and approximate the shapes of less-distorted types of clinkers. For example, Lee Brick and Tile Company's Pinehurst #610 brick has a uniform raised texture on its face but is randomly nicked and roughened on the back from the manufacturing machinery to resemble less- explosive-looking clinkers. Blended with true clinker bricks and a mortar that's color-matched to the original, the brick is an economical alternative to tracking down reclaimed clinkers, which can be pricey depending upon the quantity and the source.
Gavin adds that it's important to remember that with clinkers, the finished effect is all in the bricklaying. You can lay clinkers in a straight line, and they won't be that unusual. But if you find a mason who knows how to set the butt ends and corners out on various bricks, the effect can be fabulous. Not a bad trick for a brick that was once thrown out with the trash.
Susan VanHecke is a journalist, author and owner of a 1932 clinker brick Colonial Revival house in Norfolk, Virginia.