All week long the 23 of them have been working in a sweltering, sealed basement room at the Corcoran School of Art, making sculptures of the same model in what may be the most intense artistic competition of its kind.

They are art students or recent graduates, and they come from as far away as California. They paid their own way here and put themselves up at the Y or stayed with friends. The $500 first prize will mean little.

But that's not what it's about. It's about recognition. It's about creating a work of art on the spot, to a deadline. And being judged on it, head to head with your peers.

They worked for 24 rigidly monitored hours over five days, each starting with 50 pounds of clay and equal lengths of aluminum armature wire. Now it is all over, and the judges are downstairs comparing the model and the statues. The artists mill around the Corcoran lobby waiting for the word.

They chat quietly and joke, a friendly group. But their eyes are restless.

Someone herds them into the theater, and they sit casually while tension swells like a giant balloon. Six pieces will be chosen for the final cut.

This is the fourth annual James Wilburt Johnston sculpture competition, established by his son, Washington sculptor Barry Johnston, "to emphasize the importance and value of academic figure study." What made it even harder was that the model posed for the judges, too.

Time's up. Still talking, some of them, new friendships formed under the pressure, they troop downstairs to confront the six pieces.

And before your eyes the group becomes two very separate groups, the chosen and the rejected.

At first some people think the winners are the ones along the near wall. Moments later they realize it is the middle row, and a few glum faces brighten, and a few modestly cheerful faces suddenly stiffen.

No names are attached to the works; it is done by number. But they all know their own. The top three winners, for $500, $300 and $200, plus an honorable mention, are to be announced by Mrs. Joseph Hirshhorn in a few hours.

"You usually never get to see the model and the piece together," remarks judge Isidore Margulies. "This is a really difficult test."

It's been a long week.

MONDAY:

For the first two hours they build the three-foot stick figures that will be the sculptures' skeletons. Things are slightly hectic because not everyone has a proper stand yet.

"I'll make a bet," mutters Rick Hart, a foundation board member who is the creator of Washington Cathedral's tympanum sculptures. He points to a stand. "The guy who did that armature is gonna win." It does look organized and sure, the arms neatly at the sides and not waving wildly in the air.

When everyone is ready, Johnston has the rules read aloud, and the model takes the stand. He is Juan Paredes, 31, a D.C. native who does this for a living, 25 minutes on, five minutes off, holding a pose for as long as it takes. Sculpture modeling is the hardest kind of modeling, for a person is limited by fatigue and gravity, he points out. The pay runs about $6 an hour.

"I'm shy, basically," he says. "I keep a low profile, just put on a gown and go off when I'm not on the stand. Action poses are harder, of course, but there's a greater fudge-factor in a slow medium like this: You can move a little."

When he goes to work he stays alert to his surroundings, rarely slips into a dream state, though sometimes he wishes he could. "It lasts forever. At the end of the day you'd just as soon be shot." No, he's not an artist himself.

It takes another hour to decide on the pose. Paredes strikes six basic postures, with the contestants making suggestions about turning the head or moving the hands. In the final vote, 13 favor the winning pose. After lunch the group is sealed in the room and work begins. Monitor George Lewis, a Corcoran third-year student, will turn Paredes on his stand every five minutes.

For a while nothing much seems to be happening. A lot of them just sit and sketch and stare. Gradually, people load clay on their armatures. A few minutes ago there was some quiet talk over the coffee and doughnuts. But now, no one is talking and all you can hear is the slap of clay and the squeak of stands turning.

WEDNESDAY:

The difference since Monday is amazing. Some of the pieces look almost finished. Most are still rough with scratches and dabs of clay. Hardly anyone has tackled the face yet, except for outlines. The feeling is, it's better not to be too far along this soon. One sculpture has the classic bald head of a studio figurine, though the model is definitely frizzy. One, nearly finished, has no penis.

The amazing thing is how different the sculptures look. The separate parts of the body are generally very accurate, despite a too-high shoulder here and a too-broad chest there. The difference is in how the parts come together. At a glance, you can see that some works--so far--simply haven't captured the relaxed, slim, sleekly youthful body, a Donatello David.

Some pieces show a stiff and tense young man. Some show a strongly muscled academic figure that seems to have been done from memory more than from the actual person before their eyes. One piece was turned so much that it unscrewed from its stand and fell off--into the arms of the sculptor. Who turned creamy white but hung on.

But the statues are changing, minute by minute. People stare and stare at the model, swipe at the clay, stare and stare, dart out to study an arm or a leg, dash back to their stand and swipe some more clay off. More comes off than goes on.

Charles Mitchell is 59, "the world's oldest living art student," retired chief designer of cars for GM in Detroit. He's been taking art fulltime for two years. Valerie Ambrose, who came in fourth last year, says it's less tense this time because the rules are more specific. But still tense, all right.

Beatrice Corn left the Monday session, put on her Potomac-matron outfit and attended her son's high-school graduation at Constitution Hall, then jumped back into her jeans to work.

"It's very scary. You work from 9 to 4 and your arms hurt from holding them up all the time, and your back kills you. I go home and sit in the kitchen for two hours unwinding. I have six kids, and I told 'em this is mother's week. I gave them all jobs taking care of each other. They're rooting for me."

FRIDAY:

Everyone crowds around the winning pieces, and judge Walter Hancock, the distinguished sculptor who is Barry Johnston's mentor and who helped the younger man set up his Art for Humanity Foundation and this extraordinary competition, talks about the decision.

"Continuity is what we were after, a flow of the body masses, subordinating details," he says. He follows the movement from ankle straight up to the breastbone, points out the unity of arm and neck. "The left arm is not as good here. There's a little interference between the wrist and head."

The third judge, Eric Parks, notes slight faults in a losing work. Some heads are too large, some bodies too herculean, some faces too flat, some pieces too roughly surfaced to show the shape truly.

"Not many of you really got the character of Juan," Hancock comments, "though there was surprising consensus on the pose. All the work here was remarkably good."

One by one the contestants get critiques. "It's the smoothest I've ever done," says one woman, shrugging. "I tried to finish it too fast," a man admits. At the back of the group a young man touches the shoulder of a young woman sitting alone. She turns to look at him, unsmiling.

Next year, Johnston hopes to offer more money and more work time.