The Pittsburgh Glass Center joins in the commemoration of the city's 250th anniversary with "Glass & Steel: Art Transcends Industry," a celebration of the city's rich industrial heritage and its vibrant creative future.

The exhibition showcases the work of 31 artists from Southwestern Pennsylvania. The wide variety of art on display, much of it created in the center's flameshop or casting studio, makes for an engaging, visually appealing exhibition.

Visitors may be struck by the diversity of themes that emerge when contemplating the exhibition's open, eclectic organization. The show is not installed by theme. However, connections among objects can be made piece by piece.

One prominent theme that arises is Pittsburgh's position as an innovative producer and user of glass and steel products. Several artists combine these materials in imaginative ways to communicate strong messages concerning urban flight, emptiness and Pittsburgh's past.

Brian Engel's "Escape Mechanism #2" is a technically challenging fusion of a vintage bicycle and glass elements. An intricately woven glass basket is affixed to the front of the bicycle, while a period-issue baseball glove rides on the rear fender -- behind an imaginary peddler. A piece of blown glass attached to the bicycle's frame displays a map of the city that includes the location of Forbes Field. Engel's work provokes viewers to contemplate Pittsburgh's glorified, yet dismantled, monuments. At the same time, the bicycle itself serves as useful transportation within, or away from, the city.

Tina Rojas' "Vacancy" also represents a unique combination of glass and steel. A wood box, with slightly rusted steel parts, rests open on its side. On the inside, 36 kilncast glass keys hang. The keys have a frosted appearance and are arranged on hooks, reminiscent of an old-fashioned motel's display of room keys. One way to read "Vacancy" is to notice that all hooks have a key. The proprietor has plenty of room, but too few tenants. Applied locally, "Vacancy" could refer to Pittsburgh's dwindling population, which leaves empty spaces waiting, anticipating an influx of new citizens.

Botanical designs also can be seen throughout "Glass & Steel." Two exceptional wall-mounted sculptures by Chris Clarke titled "Leptotes" and "Tenuifolia" express nature's ability to display variety in color and shape. Twists of steel rods protrude from shellacked tree trunks, which are interspersed with organically shaped colored glass. Clarke's art effectively combines glass, steel and wood (three heavy materials) into flowing shapes that appear fresh, colorful and amazingly airy.

Cleverly placed in the foreground of Clarke's floral works is Anthony Schafermeyer's "Because," a large, golden-colored glass beehive with three steel bees awaiting entry into the honeycomb. Paige Ilkhanipour, marketing director at the Pittsburgh Glass Center, explained that "Because" is the most technically challenging blown-glass work in the exhibition; Schafermeyer used an ancient Italian mosaic glass technique called murrine, in which glass pieces are precisely melted and fused together. Leslie Kaplan's especially eye-catching and intricate pair of "Weird Botany" necklaces, comprising borosilicate glass, steel, silver and copper wire, complement the other botanical works on view and are part of the exhibition's larger display of jewelry. A key ingredient in borosilicate glass is boron, which increases the temperature at which the glass will melt and requires a somewhat nontraditional production method. An advantage to using borosilicate glass for jewelry is that the glass resists breaking and, if it does break, the glass is less likely to shatter into pieces.

"Glass & Steel" exhibits several conventional glass pieces which also incorporate steel, such as Dan LeDonne's swirling and arcing room divider, titled "Screen Series (No Boundaries)."

There are also several overtly Pittsburgh-themed works. Most interesting among these is Jeffery Phelps' "On a Clear Day," a view of Downtown Pittsburgh, perhaps from the North Shore, that is reverse-painted on fused glass panels. Phelps' scene is highlighted by a frame which, as the spotlights shine from above, projects shadows on the wall consistent with the shapes of the city's Three Sisters bridges.

Visitors to the Pittsburgh Glass Center will discover their own themes among the works on display, which are also available for sale.

"Glass & Steel" continues through Sept. 5 at 5472 Penn Ave., Friendship. Admission is free. Hours are 10 a.m. to 7 p.m. Tuesdays through Thursdays and 10 a.m. to 4 p.m. Fridays through Sundays. For information: 412-365-2145 or www.pittsburghglasscenter.org.