Some of the most important art being created in Washington these days is the product of fund-raising efforts for various charities. Last year saw an explosion in the number of artists -- musicians, actors, visual artists -- joining forces to raise funds for a variety of causes and nonprofit entities.

The Lab School of Washington, a private school for the learning disabled, had been looking around for a fund-raising idea. Washington artists Gayil Nalls and Susan Paul Firestone, along with Lab School board members Samia Farouki and Max Berry, came up with a unique concept to raise funds, and perhaps the level of artistic endeavor in the capital. They enlisted Nalls and Firestone to recruit six other artists -- Tom Green, Ellen MacDonald, Jody Mussoff, Jock Reynolds, Susan Hellmuth and Alan Stone -- for the creation of 91 limited edition print portfolios, each costing $1,600. Dennis O'Neil of Alexandria's Hand Print Workshop did the silk screening. Jane Livingston, associate director and chief curator of the Corcoran Gallery of Art, wrote the introduction to the portfolio. Each print measures 22 by 30 inches.

Their effort was anything but ordinary.

Livingston, who said she doesn't normally get involved in projects like this one because of conflicts of interest, felt that she was happier for having done so. She called the print project "a tour de force in the silk-screening medium."

O'Neil, who had never "really done a benefit portfolio" and "never worked with so many different artists before," came away impressed with the degree of talent and artistic collaboration that he certainly hadn't expected from eight different, individualistic artists.

"Their works couldn't be more different, so it was a challenge technically," said O'Neil. "Each artist came in and we worked together . . . Tom Green's took a couple of weeks. Jody Mussoff took six weeks. It was sort of contagious, and there was a sort of spirit that developed about this whole portfolio. They would critique each others' work, and there was information going back and forth in that regard, which I think is pretty unique."

After a private unveiling reception at The Washington Post Co. Wednesday, the prints will be exhibited at Brody's Gallery, 1706 21st St. NW, beginning Feb. 4. O'Neil and Nalls assembled an interesting adjunct to the portfolio. For each artist, the duo assembled the proofs, drawings "and related materials that were generated in the process" on a 3-by-4-foot panel that will also be displayed at Brody's. For information, call 965-6600. Romantic Brass Rubbings

It's never too early to think about Valentine's Day. At the London Brass Rubbing Centre in the Crypt of the Washington Cathedral, they're thinking about it, too. The aptly named Etcheses, a British couple who run the center, have come up with a way for potential cupids to express their artistic impulses. The center owns 70 facsimiles of 14th- and 15th-century brass plates copied from churches and abbeys located in Britain and the Low Countries. The facsimiles are made of a hard, electroplated resin; some of them have "love themes," said center comanager Richard Etches. So the Etcheses have culled 15 of the most romantic plates from the center's collection and are offering bargain-priced rubbings from Feb. 1 through Feb. 15. The price will average around $2.50. The center provides rag paper and beeswax crayons in a variety of colors. For more information, call 364-0030. Arts, Etc.

The National Gallery of Art has extended its crowd-pleasing "Ansel Adams: Classic Images" exhibition through Sunday. The show, consisting of a specially prepared "museum set" of Adams' photographs, was to close Jan. 12. Next stop is the San Diego Art Museum . . . Attention artists: The D.C. Commission on the Arts and Humanities is seeking applicants for its 1987 Grants-in-Aid program. For information on the grants and grantsmanship workshops, call 724-5613 . . . Young Concert Artists Inc., which is celebrating its 25th anniversary this year, will bring pianist Jeremy Menuhin (Yehudi Menuhin's son), baritone Christopher Trakas and violinist Daniel Phillips to the Kennedy Center's Terrace Theater in March and April.