AROUND HOME : Notes on Gazebos, Sconces and Teakettles : Equa Chairs

WE ALL NEED wriggle room. Within five minutes of sinking into a chair, most people cross and uncross their legs or slither forward onto the edge. Indeed, we are not built to remain in one position for long.

An ergonomic chair satisfies the body’s craving for frequent position changes. With its movable backrest and five-branched swivel base, an ergonomic chair resembles steno chairs, but cost much more.

The Equa chair, released in 1984 by Herman Miller, is to ergonomic chairs what Miller’s earlier, classic Eames recliner is to lounge chairs.

Designers Bill Stumpf and Don Chadwick, aided by time-lapse X-ray, film and video studies of seated workers, aimed for a chair that would adjust automatically to different sitters performing different tasks. After five years of research and 27 prototypes, they devised a flexible, one-piece shell, the first to use Dupont’s glass-reinforced polyester resin, Rynite.

“Traditionally, office chairs are thickly upholstered--you see the cushiness before you even sit on it. But when you look at the thin-profile Equa, you’re not sure,” says Chadwick of Don Chadwick and Associates in Santa Monica.

Indeed, first-time Equa chair sitters are in for a surprise. The slender, graceful shell, with a profile that evokes the curvature of the human spine, encourages correct posture. The H-shaped cutout near the bottom bulges discreetly to accommodate buttocks of diverse shape and weight. The remarkably adaptable self-adjusting shell seems to possess a liquid, alive quality--like a water bed but firmer.

The Equa tilt mechanism also rates as a breakthrough. Traditionally, chairs tilt at the central support column; unfortunately, when one tilts back, the edge of the front seat rises and puts pressure on the underside of the thighs, cutting off blood circulation. The Equa rights that wrong by pushing its pivot point six inches forward to a position just behind the knee. The height of the front seat edge stays constant no matter how far one tilts backward, allowing one to keep both feet on the floor while reclining.

Two more strategies promote blood circulation: a gently rounded, “waterfall” front edge instead of a (cheaper to make) squared-off seat front, and the shell’s slope downward toward the back, which encourages one to sink into the chair--further taking weight off the thighs and transferring it to the buttocks, where it belongs. It all adds up to a chair, Chadwick says, “where you won’t fidget, and your feet won’t go to sleep.”

Suggested retail prices for the Equa chair range from $325 to $1,600, depending on fabric and options. Contact Herman Miller Inc., Pacific Design Center, 8687 Melrose Ave., Los Angeles 90069 (213) 659-7600 for area distributors.