Things aren't as quiet as they seem on the gallery beat. Though many galleries (if not all) have closed until after Labor Day, there's a flurry of behind-the-scenes activity that augurs well for the coming season. The best news: After years of retrenchment, Washington's commercial galleries are expanding again, in both numbers and size. No closings have been reported.

But most exciting for those concerned with important new art is the imminent return to Washington of Nancy McIntosh Drysdale, who will reopen Sept. 27 at 406 Seventh St. NW after three years in Houston. She will occupy the handsome third-floor space originally designed for Harry Lunn (now a private dealer in New York).

Drysdale's inaugural show will celebrate the stellar list of artists she has shown over the past eight years, including Leon Golub, Scott Burton, Sol LeWitt, Martin Puryear, Jennifer Bartlett, Jonathan Borofsky, Tom Wesselmann, Robert Kushner, Richard Haas, Alex Katz and Alice Aycock.

"Artwise, Texas was fun," says Drysdale, "and there's a much better market and more collecting spirit down there. But I like Washington."

Jo Tartt, a respected Washington collector and private dealer in photography and decorative arts, is planning to open a gallery near Dupont Circle in a building currently under renovation. No opening date has been announced.

Several other established dealers are moving or expanding -- or both. Marie Martin, after two years in Georgetown, will be doubling her space when she reopens Oct. 1 in Adams-Morgan at 2427 18th St. NW, joining two other good galleries in the neighborhood: Middendorf and Jack Shainman. Martin will continue to focus on photography but will also feature sculpture, prints and drawings. The first show in the new space will feature Chicago sculptor Richard Hunt.

Brody's Gallery will also open in new digs at 1706 21st St. NW on Sept. 10, not only tripling its previous space, but bringing it two critical blocks closer to the burgeoning cluster of galleries now in orbit around the Phillips Collection.

Nearby, Kathleen Ewing isn't moving, but she's renovating and expanding her Connecticut Avenue gallery to twice its present size. She will reopen in September with new space for her popular photographic workshops. News of Franz Bader

The Franz Bader Gallery is not only moving, expanding and organizing a relocation sale (a potential bonanza for print lovers, scheduled to begin Aug. 20), it has also just opened a refreshing summer show of watercolors by Washington artist Dora Lee -- all intimate scenes of great cities made in her characteristic style, which somehow manages to cross Maurice Prendergast with the Orient.

It will be the gallery's last show at the present 2001 I St. NW location, but it will not be Franz Bader's last show. Though he recently sold the gallery to former private dealer Wretha Hanson, the transfer of ownership will not take place until the end of this year. Thus, when the new Franz Bader Gallery opens on Sept. 10 -- in a large space now being renovated at 1701 Pennsylvania Ave. NW -- it will feature a group show of Bader's gallery artists, most of whom have agreed to continue under the new ownership. Happily, the space will also include the bookshop, which will continue under the able leadership -- and now ownership -- of Sabine Yanul.

The relocation sale, which starts Aug. 20, could make overheated collectors glad they stayed in town. Featuring primarily an odd lot of original prints by Braque, Callot, Daumier, Dehn, Klinger, Pascin, Piranesi, Tamayo, Rowlandson and Villon, the sale will also include some Eskimo art and a few rare paintings by Alma Thomas and Sarah Baker. Hours at Bader are Tuesdays through Saturdays, 10 to 6.

And the new Anne O'Brien Gallery, though wholly unrelated to the Bader Gallery, will open in September at the same 1701 Pennsylvania Ave. NW address. It will be devoted to contemporary art glass. Caribbean Art

Among other shows on view: "Caribbeana '85" at Fondo del Sol, 2112 R St. NW -- the fourth annual exhibition of area artists either from or influenced by the Caribbean islands, along with others who live there.

The best art, apart from the stylized paintings of animals and plants by Haitian painter Audes Saul, is the original sequined voodoo flag and banner made by unknown artists in Haiti, and masks commissioned from folk artists in Ponce, Puerto Rico. The biggest curiosity: a painting by Trinidad native Geoffrey Holder, better-known as a dancer, choreographer and basso-voiced star of the Un-cola commercials.

Standing out among works by area artists are the sculptures by Michael Auld from Jamaica, and small assemblage boxes by Jorge Sommariba from Nicaragua. A multimedia video installation by Rebecca Crumlish, in collaboration with several other artists, provides a nice evocation of the Caribbean islands. The show will continue through Aug. 15. Hours are 12:30 to 5:30 Tuesday through Saturday.