THE strain of inventing interesting ideas for summer group exhibitions often shows. For example, "Adorning the Body," the midsummer invitational show at Gallery 10, is a bit on the cute side.

Much of the art, made especially for the show by 36 invited artists, seems predictable and half-hearted, and some of it only distantly related to the theme, if at all. But Peggy Swartout got the idea. She responded by decorating a white silk kimono with delicately colored transfer printings of photographs of the Hiroshima bombing and its aftereffects. It takes a second to register the pretty garment hung on the wall and a few seconds more to decipher the content of the images. Adorning the body, indeed.

Carla Rosenzweig contributes a fairly hard-hitting sculptural ensemble, "Hair Pieces," consisting of wigs and rolls of hair stuffed rather aggressively into partially transparent and roughly made wooden boxes. Margaret Kressley offers two bright and apparently well researched drawings depicting various special outfits of an Egyptian pharaoh and queen in the form of paper doll cutouts.

Among the invited artists there are several who did not have to make special efforts. The theme of physical adornment fits naturally into their view of the world and their artistic output. Exotic dress and partial undress have always been a big part of Noche Crist's dreamlike world of opulent sexuality. Costume and fashion play similarly crucial roles in Claudia de Monte's ongoing exploration of role-playing and self-definition.

This also seems to be true of Sumie Edagawa Putnam, an artist whose work I hadn't seen before. She contributes an impressively varied ensemble of works all based upon elegant kimono patterns: an expertly made intaglio print combining etching and aquatint; a diminutive tableau that is a sort of kimono closet with rock garden; and three small, triangular wood sculptures with wraparound patterns painted onto them.

Gallery 10 is on the second floor at 1519 Connecticut Ave. It is open from 11 a.m. to 5 p.m. Tuesday through Thursday. "Adorning the Body" continues through Aug. 13. At the Art Barn

"Directions in Surface Design," the title of the show at the Art Barn, could mean anything, and does, in this potpourri of work by 10 younger artists from the metropolitan area. There is photography, painting, pottery and sculpture, and a lot of not very good, or very awkward, or decidedly unoriginal, work in all mediums.

Berne Israel's prints are technically competent. Nadia Mered's disc-shaped ceramic vases are made with impressively thin layers of clay. Thach Nguyen's sculptures of wood and silk are like Naum Gabo constructions made to resemble birds. David Gracyalny's paintings have a great deal of energy but seem to be going off in several directions. John Hock's work--expressionistic paintings he calls "Aggression Studies" and free-standing painted sculptures--shows sharp flashes of invention and skill. His "Syracuse Pink Pig," a flat steel cutout of the animal, roughly painted and standing on a hard steel beam, is the freshest work in the show.

The Art Barn, 2401 Tilden St. NW in Rock Creek Park, is open Wednesday through Saturday from 10 a.m. to 5 p.m. and Sunday from noon to 5 p.m. The show closes Sunday. Invitational Sculpture

Works by Harriett Matthews, a New England artist on the faculty of Colby College in Maine, make up the annual invitational sculpture exhibition at the Montpelier Cultural Arts Center. Matthews' metal sculptures, displayed on pedestals, are abstracted visions of the architecture and land forms of Italian hill towns or other sites in Italy and Greece.

The pieces are clearly intended to evoke some of the mysteries of these ancient places and this they do. There is no questioning the sculptor's skill or the earnestness of her quest. But somehow these pieces are not as persuasive as one would like them to be. They lack the wit and the sparkle of scale one finds in the works of Charles Simonds or the Poiriers (a French husband-wife team) or others who make diminutive works with similar themes.

The center, at 12826 Laurel-Bowie Rd. (near the Laurel-Bowie exit of the Baltimore-Washington Parkway), is open seven days a week from 10 a.m. to 5 p.m. The show continues through Aug. 15.