How do you get a hydrojetting contractor to let loose his inner Picasso in public? Just ask, according to Brian Gleeson, owner of Midwest Mobile Waterjet LLC, based in suburban St. Paul, Minn.

The firm’s waterjetting wizardry is on exhibit at the Walker Art Center in Minneapolis. Midwest crews used high-pressure water to blast thousands of holes that, from afar, create a random, paisley-like

pattern on the exterior of the center’s walls, made out of poured concrete mixed with pea gravel.

“It came out of left field,” says Gleeson. “It’s really cool. I’ve never seen anything else like it.” The architecture firm that designed the center, which opened in 2005, asked Gleeson if he could replicate a dot pattern on the exterior of the center’s parking ramp and on its lobby floors. Intrigued, Midwest workers built concrete slabs and pattern mock-ups and “blasted the heck out of them,” Gleeson says.

When they figured out how to make it work, the design was downloaded into a computerized waterjet cutting table. Then the machine cut a stencil out of about a dozen, 5-foot by 10-foot sheets of metal 1/8-inch thick.

Next, the workers bolted the metal sheets to the center walls and floors and went to work. They used a Jet Edge 36-250 DX waterjetter (made by Jet Edge Waterjet Systems), which generates 40,000 psi/4 gpm, equipped with a Gyrojet multi-jet rotating nozzle, made by Siddharth Enterprises.

“You can’t cut concrete unless you hit it with at least 20,000 psi,” Gleeson notes. “As long as you hit the wall perpendicular, and not at an angle, you’re good.” Since that project, Midwest did a similar job at a high-end condominium development in New York City. But Gleeson says the company has no plans to broaden its reputation for artistry.

“We haven’t really marketed it,” he says. “It’s pretty expensive to do.” But getting your work displayed at a major art gallery? Priceless.