Back in the late '50s and early '60s, a group of California artists liberated clay from its traditional role as "vessel" and introduced a vital new genre of ceramic sculpture.

The early manifestations were called "funk art" and combined humor (often of the bathroom variety) with prevailing '60s irreverence. One key figure Robert Arneson, produced a shocking ceramic typewriter in which lacquered fingernails replaced the keys; and David Gilhooly made deliberately tasteless objects, such as "Elephant Ottoman," a life-size elephant hoof with upholstered seat -- all ceramic.

The richness and variety of what followed -- big, outrageous, nonutilitarian ceramic "objects" with Dadaist and pop overtones -- is outlined in the Renwick's superb exhibition, "A Century of Ceramics in the United States, 1878-1978," which closes tomorrow at 5:30 p.m. If you haven't seen it, do. If you have, head for the Fendrick Gallery, 3059 M St. NW, where Robert Arneson is having a one-man show.

Arneson, now in his late 40s, has contined to produce funny, punning sculptural works like the head of George Washington on a pedestal entitled "I'm the One," which refers to his image on the $1 bill. More recently, Arneson's own head has become his chief subject matter. His big blue slef-portrait, called "Breathless," is prominently displayed in the Renwick show.

Arneson has also been producing ever larger feats of clay, and the centerpiece of the Fendrick show is a round floorpiece -- 9 1/2 feet across and divided into pie-shaped wedges -- which he calls "Impression of the Artist as an Incorporeal Witness to the Center of the Universe." An autobiography of sorts, the work features the impression of the artist's nude body plopped into a huge blob of clay, surrounded by imprints of his feet, ears, nose and face. The wedges were divided into 48 jigsaw-like pieces for firing and glazing in a dazzling array of lusters. All together, it is a tour de force of ceramic art, although it leaves the viewer with little to think about.

There are also several drawings in this show: some studies for the big pie and others that portray Arneson in persistent bad-boy poses -- his finger up his nose, for example. Frankly, this kind of naughtiness seems a bit dated. By now, Arneson out to be able to capture our attention -- and keep it -- with somewhat larger ideas.

Upstairs at Fendrick, realist Sondra Freckleton (wife and collaborator of Jack Beal) is having her first Washington show -- big, light-drenched watercolors, still lifes distilled from the homey subject matter that surrounds the aritsts on their upstate New York farm.

A baby duck peers from a basket in front of an antique ribbon quilt; an appliqued tablecloth seems real enough to touch; a wheelbarrow is filled with a harvest of homegrown summer vegetables.

In the most riveting work, Freckelton deals with a trailing waxy begonia plant, conveying not only the look of the plant, but the artist's experience of it. Both Arneson and Freckelton continue on view through Feb. 9.

Now that the furor over the Corcoran's show of nine Washington artists has died down, gallery goers should take a look at the concurrent show at Lunn, 3243 P St. NW, featuring two of the stars -- Kevin MacDonald and Michael Clark.

MacDonald's work-tenderly drawn interior scenes redolent of calm, cool light and poignant emptiness -- sustain the high level of quality established by his color pencil drawings at the Corcoran. He is surely one of the best young artists now at work in this city.

Michael Clark's show, however, is a complete bomb, his worst to date. Presumably these paintings were the dregs left behind after the Corcoran made its choice, but Clark should never have let any of them leave the studio.

Clark's neo-pointillist version of the Lincoln Memorial is bad enough. But the portrait of a horse seen from the rear is merely incompetent, the pop-inspired car in a sea of dots merely ridiculous. Only one painting -- a landscape -- sustains a modicum of interest. It is Clark's landscapes at the Corcoran that also emerge as his strongest statements to date.

Clark made what now seems an overly large reputation some years back with his early, funny pointillistpop versions of George Washington, sure-fire subject matter during the Bicentennial year, and still amusing now. But these recent nudes, cars, horses and polka-dot memorials suggest an uneven output, to put it generously. His next show will be watched with great interest to see whether he can recoup the losses suffered here. Both shows continue through Feb. 26.