Few would question the high seriousness of a sculptor using bronze, wood or welded steel. But what of nontraditional sculptural materials like plastic or glass? Can they inherently diminish even a good artist's chances for success? Or perhaps enhance it? The question came up so often in galleries last week that it seemed worth exploring.

Washington artist V.V. Rankine is a case in point. She has been constructing three-dimensional, semiabstract sculpture from sheets of sleek, shiny plexiglass for years, most recently the smoky-black transparent variety that she uses exclusively in her show now at Franz Bader.

For me, plexiglass has always made better looking picture frames than art, though Rankine temporarily disarmed that prejudice last year with her monumental generic running figures shown at Washington Square. They had matte, opaque surfaces and appeared to be made of black painted wood, or perhaps painted metal. It turns out, however, that they were built from plexiglass that had been sanded, a process that transformed -- and denied -- the inherent qualities of their surfaces, resulting in work that was altogether satisfying.

Yet the prejudice kept flickering in Rankine's current show, even in the most agreeable works, such as "Night Runner" -- a semiabstract wall relief suggesting a lone jogger making his way through the darkness of an urban landscape. Though the figure has the acceptable matte, sanded surface, he is set against a shiny black plexi background that shatters the silence, even though it can surely be argued that the mirror-like surface is justified here because it suggests the glow of city lights.

But then there's the matter of the plastic boxes. "Que Passo?," perhaps the most affecting work on view, is as haunting as an ancient funerary sculpture, with two generic figures sitting side by side, barely discernible inside the smoky plexi box in which they are entombed. True, the box adds to the sense of distance, of mystery. It even apes the way ancient sculpture is often displayed in museums. But after all these rationalizations, it is still jarring, and I simply wish it would go away.

There are less successful boxed pieces about which there can be little argument: "Canyon," for example, might well evoke a western landscape in its basic, craggy forms, but it is done in by the cute, butte-shaped plexi box that surrounds it. As for the wall relief "Ceremony of Innocence," there is no deliverance from shallowness, even in the pretentious title, taken from Yeats.

Oddly, the one place where the shiny/dull surfaces work well is in the huge, squarish abstraction titled "Oblique Accent," which recalls a high altar from some ancient Mayan city. Or could it be Hollywood?

Rankine's thought-provoking show will continue at the Franz Bader Sculpture Gallery, 1701 Pennsylvania Ave. NW, through June 21. Hours are 10 to 6 Tuesdays through Saturdays.

Sculpture at Anne O'Brien

Can glass be taken seriously as a sculptural medium? At the Anne O'Brien Gallery, located above Bader, the question is always relevant, since O'Brien specializes in the more adventurous artists working around the country in glass.

Don't sneer until you've looked. It turns out that lots of interesting sculptural work is coming out of the decade-old renaissance in studio-glass -- enough, in fact, to have spawned three good glass galleries in the area: O'Brien, the Glass Gallery in Bethesda (the first) and Maureen Littleton in Georgetown. All are worth a visit.

O'Brien is currently featuring a young area artist, Jeffrey Chapline, who creates what he calls "contemporary fossils" -- sand-cast glass reliefs and three-dimensional objects. Using the debris of modern society -- broken radios, TVs, cameras, toys, tools and such -- he produces updated "junk" sculpture by arranging such items in a sand mold, making a cast and then filling it with molten glass.

The results have a sandy, distressed, cobwebby surface that gives them the aura of old objects unearthed in an archeological dig. The best examples also convey messages and puns or provoke thought about the nature of contemporary society by juxtaposition and implication: "TV," for example -- one of several hexagonal relief panels -- combines a broken TV set with toy soldiers and a toy gun in a way that forces viewers to make connections in their own heads; "Christ" includes a crucifix, a dove, a whiskey bottle and an overturned toy car -- pretty rough stuff in any medium.

Beyond giving worthwhile content to his work, Chapline has also done something else: He has gone beyond mere experimentation to expand meaning. He would seem, in this first show, to be an intelligent artist who happens to be working in glass, and with promising results.

The show continues through June 21 at 1701 Pennsylvania Ave. Hours are 10 to 6 Tuesdays through Saturdays.

Prize Winners at the Glass Gallery

The Glass Gallery, under the direction of Sarah Evelyth, was the first in the area to promote contemporary art glass, and for the past several years has sponsored a national invitational show, offering the three prize-winners a show of their own. The winners of this year's invitational are the subject of the current show in Evelyth's handsome, newly expanded space at 4931 Elm St. in Bethesda, and though the others are more experimental (or perhaps because they are), the most traditional of the three -- Curtiss Brock -- comes out best.

Brock makes blown, cut, polished and acid-etched vessels that are masterfully made and lush in every way. Some, shaped like ancient stone grinding vessels, even take on the expressive qualities of sculpture, as they cradle forms within. But Brock's work stands out because he carries his craft to such masterly heights, not because he moves into the realm of high art.

David Leppla fuses tubes of clear glass to emulate the undulating nature of undersea flora and fauna, and Chris Davis Rockmore toys with landscapelike combinations of glass and metal. Neither, however, has gone beyond the experimental stage so far as sculpture is concerned, and in a real way they define the boundary where glass-making and art divide.

This show will continue through July 12 at 4931 Elm St. in Bethesda. Hours are 11 to 5 Tuesdays through Saturdays.