Fluted Beams: Knot Your Normal Wood

Fluted Beams: Knot Your Normal Wood

Imagine taking a piece of wood in your hands, then bending and twisting it into any shape imaginable, from a tight curve to a twisted pretzel knot. The possibilities are endless, but of course, wood only behaves that way in your dreams, while you are fast asleep.

Well, wake up; there’s good news. This amazing wood really does exist. No, I am not talking about some reconstituted wood substitute or even a weird or dangerous chemical process. I’m talking about the hardwoods you know and love, like oak, ash, maple, and walnut, among others, altered to make them easy to bend at room temperature.

Although this all sounds too good to be true, I can assure you it is real. I’ve tried it myself and it is indeed like a dream come to life. Curious about how it’s all done? Allow me turn you over to Chris Mroz, the man behind Fluted Beams, the only company in this hemisphere making and offering this unique wood.

“I established Fluted Beams about six years ago as an architectural fabricator,” Chris explained. “What interests me are organic sculptural curves and shapes. I wanted to make the crazy things out of wood that architects design and no one else can build.

“After finishing a master’s degree in Canada, I worked as a sales consultant in the pulp and paper industry, eventually becoming a specialist in recycling technology. For years, I worked selling engineering and manufacturing CAD/CAM software to the aerospace and marine industries. While doing that, I did some boat building and came up with a product that I wanted to commercialize, which I called a fluted beam.

“I basket wove boat ribs into a grid shell, which created a diamond pattern, then covered the structure with Dacron. Rather than separating the wales with individual square blocks, I bent one piece of wood into a zigzag wave pattern and captured it between two other bent pieces. That was the first fluted beam. I realized I could scale up that idea into architectural size and make all sorts of fluted beams for a variety of construction and design purposes.

“What made it possible was a compressed hardwood from Denmark. It was originally developed by The Danish Technical Institute and was licensed to Compwood Machines. I own the only machinery in the Americas to make this, and am the major world supplier of this unique material. I start with green lumber, mostly temperate hardwoods, and dry it to around 25 percent moisture content, what I call half-dried. It’s at the point where the free water is out of the wood, but the bound water is still in the cells.


“The wood is then autoclaved, a process of adding steam under pressure, which plasticizes the wood. Then the wood is put into a hydraulic press to compress its length about 20 percent. In other words, I take 10-foot planks of wood and turn them into eight-foot long planks. This forces the cells to slide into and over one another. The wood stays in a press overnight after the compression in order for the stresses to equalize, then it comes out of the press and is put into plastic bags for storage to maintain the moisture content. That’s the way it is shipped to a customer, and it can be stored for years that way and still remain flexible.
“As long as the wood is moist, it is extremely flexible. In fact, it is so flexible that you can take it and tie it into a knot. A one-inch-thick plank can be cold bent into a five-inch radius. Normally, wood cannot stretch, but this wood can. Thus, when you bend it, the wood stays compressed on the inside but stretches on the outside without greenstick fractures or stressing. This can all be done freehand with no pressure straps.

“Once the wood dries to about seven percent moisture content, it becomes stable and holds its bent shape. Ideally, it should be dried on its bending form. You can air dry it, but it takes a very long time. Most people put it on hot air ducts or put it in a drying box at 120 degrees F, which takes about a week for a one-inch-thick part. Because most cracking and checking shows up in early drying, you can typically dry it hard and fast without any of those problems.

“Because of the size of my press chamber, the largest planks I make are six inches wide. I make up planks in five and eight quarter stock in eight-and-a-half-foot lengths. The original product was developed to make Windsor chair backs, but I feel there are applications far beyond that. To that end, I have made a number of products that stretch the possibilities. Because this material bends more like wrought iron, I get some of my design ideas from that area. Unlike steam bending, which encourages gentle bending in only one direction, compressed hardwoods will bend simultaneously in three dimensions. I call it sculptural wood bending.

“While exceptionally versatile, it is a bit expensive, running about $25 a board foot. However, you can do things with it that are simply not possible with any other wood. I sell bendable wood directly from my website, and currently sell 10 different woods, including  white ash, red oak, white oak, rock elm, American beech, hard maple, hickory, black locust, black cherry and black walnut.

“Although I do sell the wood in its unbent state, the primary focus of this business is to create unique and unusual bentwood fabrications. Most of my customers are architects, designers, furniture factories and musical instrument builders. In fact, my biggest customer at the moment is a drum maker. I see curved wine bars and kitchen counters along with structural columns and beams as the direction of greatest growth in this industry.

“Inlaid architectural columns are another interesting new direction. Oddly enough, when you inlay this wood in a pattern into the surface of a green log, the inlay pattern stabilizes the surface so the log does not check during drying.

“I look for projects that otherwise could not be done in wood,” Chris summed up. “Granted, this stuff makes many normal bending jobs easier, but creating the impossible is what keeps me up at night.”

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