Hyundai, always searching out new technology and processes to increase the luxury quotient of even its most affordable cars, is employing a very old material to dress up its interiors.

Realizing that cloth-wrapping the interior pillars of the ’12 Elantra compact and Accent subcompact would be cost-prohibitive, Hyundai engineers, working with suppliers Hyundai Engineering Plastics, Shinki Intermobile, Plastech, and Kopla, opted instead for a unique composition of plastic resin, fibrous material and volcanic rock to create the pillar trim piece and give it an upscale appearance.

Yes, it turns out volcanic rock, the same substance that is useful for smoothing rough feet, also helps plastic convincingly mimic cloth, although the discovery came about by happenstance for Hyundai.

“We had a supplier come to us that was using volcanic rock, and we were trying to find different types of (additive) that made stronger plastic resins,” Jake Welland, engineering manager at Hyundai-Kia Technical Center in Superior Twp., MI, tells Ward’s in a recent interview.

“It didn’t work out so well for using it for things like bumpers, so we thought, ‘Can we use (volcanic rock) in something else?’”

Hyundai engineers at the same time were exploring ways to make interior trim pieces look more high-end. They decided, after some experimentation, that volcanic rock would be a good replacement for talc as a filler in pillar covers.

Not only does the addition of 0.5% volcanic rock to the 1% fibrous material/98.5% plastic resin mixture make the Accent and Elantra pillars appear cloth-covered, it also makes scratches less obvious.

“Talc is a common filler for polypropylene materials, however, one of the problems with talc is that when you scratch the plastic it whitens and it looks a little bit cheap,” Welland says.

When the pillars with volcanic rock are scratched, the gouge still may be noticeable but doesn’t have as much contrast as pillars using talc, he adds.

While he can’t give dollars-and-cents figures, Welland says it is about half as expensive to injection-mold a pillar trim piece with volcanic rock for the cloth look compared with an actual cloth-wrapped pillar trim piece typically found in luxury models.

However, the cost of the volcanic-rock pillar is a “little bit more expensive” than typical injection-molding of an A- or a B-pillar, using polypropylene with resin, he says.

While Hyundai engineers are pondering other interior trim uses for volcanic rock, Welland isn’t sure of its usefulness beyond the pillar-trim application.

“Which interior parts are you trying to get looking like cloth?” he asks. “There’s not a lot more besides the pillar materials that you’re trying to do that with.”

The use of volcanic rock in passenger vehicles is not without precedence.

In the current-generation Acura MDX, which launched in 2006, Honda sourced from Azdel, a joint venture of GE Plastics and PPG, a product called VolcaLite for the cross/utility vehicle’s headliner.

Basalt mineral fibers combine with polypropylene resins to create the substrate, Frederick Deans, market leader for Azdel's glass-mat thermoplastics business, told Ward’s in 2007. The application was attractive to Japanese OEMs because of end-of-life regulations in Japan, which require that vehicles be recycled.

Welland says Hyundai also uses the volcanic-rock pillars in the Korean-market Hyundai Sonata midsize sedan.

As of 2007 ASATech, a subsidiary of the Austrian-Ukrainian Asamer Group, had 20 rock quarries in Central Europe and was pitching basalt to auto makers, after selling it in a variety of forms to various industries, including cement makers.

The family-owned supplier wanted to see basalt used in high-pressure tanks for hydrogen or natural-gas vehicles but admitted at the time it was fighting an uphill battle, as basalt was more expensive than glass fibers typically used in tank construction.

Hyundai says it plans to submit the volcanic-rock pillars for the 2011 Society of Plastics Engineers’ Innovations in Plastics competition.

– with William Diem