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Near the southeast curve of Lake Nokomis sits a coal-black sauna. The little teahouse-inspired structure is a dream realized for Steffanie Musich and her husband, Matt. It also represents a growing local interest in shou sugi ban, a wood-scorching technique that has been used in Japan since at least the 1700s.

The Musiches were first exposed to shou sugi ban in Japan, on a snowboarding trip to Hokkaido. They were wandering the streets of Tokyo, and came across a stark, wooden building, maybe a temple. With the sun at just the right angle, they could see a kind of subtle opalescence moving across the wood — obsidian to smoky dark gray, ink, charcoal and all the dark hues in between. They didn't know what they were looking at, but their architect, Jody McGuire of SALA Architects, recognized the treatment right away when the Musiches brought out their trip photos. McGuire explained that generations of Japanese people have burned lumber to protect their homes from bugs, rodents, rot and, paradoxically, fire.

Until recently it was rare to see examples of shou sugi ban in the West, but lately scores of young designers have been embracing the age-old process, in part to avoid using toxic sealants and stains. It works because charring so transforms wood at the cellular level that it becomes remarkably fire-resistant, like a blackened campfire that refuses to reignite. The flames also burn away insect-attracting oils and leave behind a protective surface layer of black-silver carbon. Some shou sugi ban homes in Japan are more than 100 years old and still in terrific shape.

"It was really appealing to us," said Steffanie. "It seemed practical. We tend to use finishes that don't need a lot of upkeep — and we really like the way it looks. It adds another interesting element."

Traditionalists stand planks of Japanese cypress into an upright funnel and allow the flames to brush upward. The Musiches devised a utilitarian assembly line, with concrete blocks for bracing the cedar planks, and a propane tank and weed burner for the charring. Over the course of five weekends, they burned hundreds of planks of cedar with help from a rotating cast of 14 friends and neighbors, lured with the promise of home-brewed beer and a chance to play with fire. One person blazed the wood, another turned it, and another swept the burned surface with a stiff-bristled brush. For the final step, they added a generous coating of tung oil, made from the nut of the tung tree. The valuable oil is prized because it hardens to a transparent luster when exposed to air.

The Musiches discovered shou sugi ban in its native land, but the origin of the stateside trend is usually credited to Delta Millworks in Austin, Texas, a lumber and millwork operation that first sold charred siding in 2010, and has since made shou sugi ban the core of its business. A Delta spokeswoman said that shou sugi ban sales at the company have increased 800 percent over the past five years.

Delta Millworks supplied all the shou sugi ban for Josh and Trish Hanson's stark, modernist abode on Little Carnelian Lake, in Stillwater Township. Their 7,300-square-foot house, designed by SALA architect Katherine Hillbrand, is practically covered in Delta's "half-gator" shou sugi ban, both inside and out. The name comes from the level of charring. With deep, successive burns, the carbon solidifies in such a way that it looks like scaly alligator hide. For the half-gator option, Delta burns the wood to a "full gator" and then hand-brushes it along the pattern of the grain. But it's not a bargain product. Delta's shou sugi ban ranges from $8 to $20 per square foot, depending on species and burn level. To cut down cost, builder Justin Streeter, Streeter & Associates, burned hundreds of planks of cedar this spring for Matt and Amanda Murray's new house in Deephaven. But he, and the Musiches, both caution that it took a lot longer than they expected.

"For future projects we're trying to figure out the best price for doing this because it's right around 40 minutes per board," said Streeter. "But it's not difficult at all, I mean, you catch on pretty quick. To overburn a board is pretty tough. I mean, to overdo it, you'd really have to sit there and torch it."

For a taste of shou sugi ban without the hundreds of hours of work, Escape Homes in Rice Lake, Wis., has introduced its latest travel-ready tiny RV home, the Escape One, made with a light pine interior with an all-shou sugi ban exterior. All yours for just $49,800.

Alyssa Ford is a Minneapolis freelance writer.