"Fire Chief" by Gene Davis. Courtesy of the Corcoran Gallery of Art.

When the Corcoran takes Sam Gilliam's "Light Depth" out of storage, its curators have to cover the floor of an entire gallery in plastic. They unroll the painting, 75 feet of stained and twisted canvas, and collaborate with the artist's team to fasten bolts to the wall of the gallery. In the end, the work drapes around a corner and across two walls. Its surface is soaked, constellated, pressed with paint, and its colors light up beneath skylights and deepen inside its folds.

What defines painting versus sculpture? What is the relationship between canvas and paint? What essential elements contribute to a complete image? During the 1950s, '60s and '70s, these questions were shifting the ways in which artists worked, and Washington, D.C., was a major center of experimentation.

An exhibition at the Corcoran Gallery of Art, "Washington Color and Light," examines the methodology and breadth of these artists, who came to be known as the Washington Color School.

"These artists were very kind of self-consciously trying to redefine paintings and to push the boundaries of painting and sculpture," says Beatrice Gralton, lead curator of the show.

[Watch a tour of "Washington Color and Light" above.]

The Washington Color School was a departure from earlier, abstract expressionist work. Instead, it focused on using color, scale and form as the most expressive, absolute aspects of making art.

"It was about color and light and form," says Gralton. "It was about an all-over approach to imaging-making. It was really this reduction to the most pure, elemental aspects of art making."

While they never considered themselves to be part of a group, a 1965 exhibit at the Washington Gallery of Modern Art (now defunct) showcased work by six Washington, D.C., artists: Gene Davis, Thomas Downing, Morris Louis, Howard Mehring, Kenneth Noland and Paul Reed. The exhibit, "The Washington Color Painters," traveled around the country, solidifying use of the term. The label stuck, becoming "synonymous with abstract painting and sculpture of the period," says Gralton. "[It] gave an energy and an enthusiasm to what was going on in the city."

What was going on in the city was in dialogue with abstract expressionists in New York City; artists associated with the Washington Color School regularly visited New York studios and galleries, and what they saw shaped their own efforts in significant ways.

In 1953, Louis and Noland visited the studio of New York artist Helen Frankenthaler, who had completed her monumental painting "Mountains and Sea." She composed the image by laying an unstained, unprimed canvas on the floor and soaking it with paint. Saturating and staining canvases with dripped or poured pigments was becoming a widely discussed technique in contemporary painting, a way of creating an intensity of color and activating the grain of the raw canvas.

"This was actually the idea of staining, to make the grain a part of the paint surface as well as the pigment," says Gilliam, who was part of a later generation of Color School painters. "Color was, of course, the principal element that was used to construct with."

Louis and Nolan returned to Washington interested in adapting these techniques in their work, and advancements in synthetic acrylic paint helped them along. In 1947, Magna paint, a brand, developed a fast-drying acrylic that could be diluted, allowing artists to pour it more easily across the canvas. Artists who could afford it began using Magna and, Gilliam says, artists who couldn't found ways to mimic the paint.

"Everybody was into transferring their thinking from oil paint to acrylic, so that when you got together, you talked paint," Gilliam says. "It was really a wet environment. You painted using as much water as you did paint. You found ways to make the paint move by hanging the canvas from the ceiling, or painting it, stretching it out on the floor."

If soaking and staining was a signature aspect of the Washington Color School (and abstract painting of the time), hard-edged abstraction was equally prominent, and it answered the same questions about color and form in a different way.

The Corcoran exhibit presents dappled, stained paintings in its first gallery, but a look through the other rooms toward the far end of the building brings Downing's "Twelve Fold" into view. The work is emblematic of the flat planes of intense pigments and geometric canvases and shapes that characterize hard-edged abstraction. Other paintings by Downing and Davis are activated by dots and stripes, which pop against the eye and create movement on the canvas.

Both galleries, Gralton says, reflect Washingon's atmosphere: hazy mornings, bright afternoons, jazz music, colorful buildings, roundabouts. A painting by Alma Thomas, "Pansies in Washington," was composed from aerial photographs of her neighborhood.

The Corcoran is an obvious place for such a show; every piece is from the gallery's collection, reflecting the extent to which the institution invested in the local art scene. Many of the artists represented in the exhibit taught at the Corcoran, showed their work there and studied the gallery's acquisitions. "Light Depth," Gilliam's draped painting, was made for the gallery where it hangs. Today, it's installed as it was in 1969 -- albeit two inches lower. The swaths of canvas and color arc across the walls, suspended from fixtures that span a corner of the room.

"It's really an interesting response to architecture, and the architecture of this building," says Gralton. "What is a painting and what is a sculpture, what constitutes a painting?"

Gilliam points out that innovative work in the nation's capital was happening in response to wider movements in art. "I guess today you'd say that we learned to think outside the box, but we also learned to think in the context of the larger art world," he says.

"Washington Color and Light" is on view at the Corcoran Gallery of Art through Aug. 14.
Images of works by Anne Truitt copyright Estate of Anne Truitt / The Bridgeman Art Library / Courtesy Matthew Marks Gallery, New York.