The fire sculptures have been constructed by the five members of Therm. One of them is Andres, who said the group's Herbst show will burn 1,000 pounds of propane and roughly 60 gallons of alcohol, a clean-burning substance more environmentally friendly -- and with a less-assaultive scent -- than the more familiar propellant kerosene.

Earplugs also will be available: Sculptures such as "The Cannon" shoot 14- foot flames and boom so loudly, Andres says, that without plugs "your eardrums will impact the side of your head."

Extreme as that sounds, Andres is quick to add that audiences should prepare "to wander into a magical landscape."

" They can expect to have their minds blown, basically," he said. "They will see fire take on shapes and colors they'd never have thought possible. They can expect to be awed."

Hucksterism? Hyperbole? Maybe a tad. But it's no idle boast. Andres and the five artists comprising Therm -- Vance Cearley, Orion Fredericks, Justin Gray, Jeremy Lutes and Zach Wetzel -- have been wowing audiences for three years. They have performed at the Burning Man festival in Nevada's Black Rock desert, at East Bay venues and for parties hosted by corporations such as Oracle and Cisco.

The Herbst Pavilion show is the troupe's first indoor performance. "It's a big step," Andres says, adding that Therm has always worked closely with local fire authorities to ensure safety. The Presidio Fire Department will have two marshals on site and a standby fire engine. (Calls to Chief Frank Richtarshich were not returned by press time.)

In his cement-covered backyard littered with, among other items, rusting trucks, tools and part of an old weight machine Andres, 35, moves to another control panel. He fires up "Stentor," built by Cearley and resembling some kind of alien life form.

" All our pieces come right out of the subconscious," Andres says. "We don't get too conceptual about our work."

Loud pops sound. Andres shows how he can flick switches to control the sequence of the pops, which herald changes in the fire emanating from the sculpture, so they become a percussive rat-a-tat rhythm. During the show, that will be accompanied by the self-billed "six-string sonic mayhem" of the Reverend Screaming Fingers -- Oakland guitarist Lucio Menengen.

" We can play off each other in an improvisational way," Menengen, 40, says.

For the "Dream" show, Oakland artist Jeremy Lutes will present part of "The Lily Pond," a sculpture he premiered at the Burning Man festival. Fifty circuit boards, designed to look like lily pads, are mounted on 24-inch steel stems. Illuminated dragonflies will rest atop some of them.

" It's very interactive and immersive, like walking through a garden with fire and light and sculpture," said Lutes, 38.

His girlfriend, Kathleen Fernald, specializes in weaving fiber optic strands on a loom to create wearable "light garments," which will be modeled by friends of the couple strolling around the Herbst Pavilion.

Andres, a sixth-generation San Franciscan, spent his first four years in France, and has lived in the Bay Area for 15 years. Always a hands-on person -- as a kid he "just liked making stuff" -- he left the UC Davis before completing a degree in engineering. (He plans to return to school next year to complete it.) After bumming around overseas, he settled down, at 25, to work on an invention -- an oil-free, water-based internal combustion engine. Over the years he secured funding, and had come close both to venture capital and corporate interest in a third prototype when the dot-com crash wiped it all out, along with his momentum." It was 10 years of my life and a huge part of my identity," he says.

Andres had spent his spare time working with fire. Why? " I ask myself that every day," he says with a laugh. "I loved fire as a boy. I started way too many fires. I don't know too many men who aren't tiny pyromaniacs." He and Cearley -- who has a fine arts background -- began building the first fire-breathing sculptures. Soon the other artists found their way to the group.

Eventually, Eccentric (pronounced E-centric) was born. The collective includes the members of SunBrothers as well as those of Light Fantastic. Andres is adamant that no one leads; decisions are democratic and sometimes arrived at heatedly. " The fire began as just joy and fun," he says. "Then I saw the possibility of doing performances in the Bay Area, and I pushed us to do that." One blustery evening three years ago, the group had its first showing -- of three fire sculptures -- in the backyard of the Crucible, a nonprofit sculpture studio, educational foundry and metal fabrication shop in Oakland. "It was a night of whiskey, rain and fire," Andres says with a chuckle.

Subsequent small showings followed, then Andres conceived of the "fire garden" -- all of the works in one place, with music. The first was mounted two and a half years ago, also at the Crucible. "It essentially blew us all to the ground," Andres says, speaking metaphorically. "We were all just floored. We had no concept that the sum was so much greater than the parts." Nor did audiences, which went wild. That's not surprising, Andres says, considering humans' elemental attraction to fire. "It has within it two sides, " he says. "It has its creative side, and it has its destructive side. It's warm, it's unpredictable, it's mesmerizing and it's slightly scary." While other fire artists play with the element's destructive aspects -- again, think of the Burning Man effigy -- Therm does the opposite, Andres says: " We create a sculpture that is beautiful in its own right, but the fire doesn't destroy it. Instead of being destroyed by the fire, it shapes the fire. We control the fire," he adds. "We can really, really, really play with (it).

Indeed, Andres says, "We can dance with (it)."
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Where to go The Eccentric Design Group's performance "Dream" starts at 9 p.m. (doors open at 8 p.m.) today and Saturday at the Herbst Pavilion at Fort Mason Center. $20.
Advance tickets: www.firegarden.org. For information, call (510) 601-6269.
E-mail Dave Ford at dford@sfchronicle.com.