CLARIFICATION: The photo that accompanied Thursday's Style Plus article on swimsuit angst was of a scene from the 1980 Hexagon Club revue. (Published 2/6/88)

It's just you. Alone with 20 bathing suits in a department store dressing room, you are trying them on. The overhead lights are a bright white, blinding fluorescent. The mirror is three-sided. One humbling failure follows another. Each suit seems to flush out the worst parts of your flesh.

After five of them you frown. After 10 you grow disgusted. After 15 you are filled with self-loathing. The sales lady knocks and you are overcome with shame.

It's also the week of the Sports Illustrated swimsuit issue.

"I've heard people moaning in there," says Katherine Long of her dressing rooms at Island Water Sports, a swim and surf shop in Georgetown. There are glossy posters on the walls of 16-year-olds in bikinis. "I had one woman last year who wouldn't leave the dressing room even though she was dressed. Her husband was waiting outside. She told him she was too upset to come out."

Trying on bathing suits can be a humiliating ordeal, a tormenting and demoralizing search. For many women, it's the motivation behind a thousand hours of aerobics, jog-walking, pool laps, dieting. Somewhere along the way to that dressing room is a trail of little pink Sweet & Low packages.

And women approach wearing a bathing suit in public as though it were the swimwear competition in a beauty pageant. "Most people only giggle or shriek when the suit looks bad," says Long. "It's a rare person, an exhibitionist-type, who will come out and model the suit for everybody."

Long believes the average woman tries on a dozen swimsuits before finding one that she likes. But it depends on the time of year. February, the month that the spring swimwear arrives in stores and on the pages of Sports Illustrated, is not the easiest of times to buy. "Women are having a hard time now, because they're not tan. Now they are terribly fickle," says Long, who has put rose-colored light bulbs in the dressing rooms to make her customers look healthier. "Oh, definitely, they buy when they are feeling more comfortable with themselves."

Winter pallor is not the only problem. Bathing-suit-buying conditions, even for perfect bodies, are foul throughout the year. For one thing, the purchase is irrevocable: Swimwear cannot be returned. For another, you have to try it on while wearing your underpants, and a pair of baggy cotton underpants squashed inside a Lycra suit is not particularly becoming. And then, there are the ratty dressing rooms -- the stray straight pins on the floor, the overhead lighting, sometimes even bleak graffiti on the walls -- not exactly a reassuring atmosphere. It's lonely.

"It's very hard to look in those mirrors," says Theresa Durazo, swimwear buyer for Raleigh's and Garfinckel's. Durazo admits to trying on 30 to 35 bathing suits before she buys one for herself. The cut and style of swimwear varies so much, women should expect to squeeze into maybe 20 suits to find the right one, she says. Durazo also encourages women to try on the new styles -- high-cut legs, low-cut necklines, whatever. She's pleased she got her mother into a bandeau top for the first time last year.

"Honey, I think it's a trauma no matter what size you are," says Nancy Radmin, owner of the Forgotten Woman in Mazza Galerie, a shop that sells bathing suits in sizes 14 to 26. "Any body has a figure problem," Radmin says. "I think society is too hard on itself. Instead of worrying about something important, we worry about the bulge in our tummy."

Radmin says she's a large-size, but she's still a sun worshiper. "I knew a girl who was a size 4, who kept her body all draped at the beach. So it's all in your mind. And there I was, 175 pounds, and it's all hanging out ... "

Many swimwear companies have responded to the self-conscious customer, the woman who thinks she's got bulges in the all wrong places. Manufacturers have created not only large-size suits, but swimsuit lines with tame tummy control -- light girdles and slimming cuts.

"Women look much better than they think they do," says Jeff Tauber, top swimwear buyer for Bloomingdale's stores. Still, they want all the help they can get. Swimwear companies Roxanne, Sand Castle and Gabar make suits with adjustable legs and straps to make the fit finer. Jantzen swimwear has a line called "Five Pounds Under," which advertises slimming cuts and "power netting" for hauling in the gut.

"In a swimsuit you see your faults. And we are just trying to help the faults look less dramatic," says Christina Balit, creator of Simply Slim, a new line of one-piece suits designed to flatter any figure. Her family founded the company Christina, one of Canada's largest swimwear manufacturers, and she's selling the Simply Slim suits in the United States, at Garfinckel's and Macy's locally. The Christina company's move into "slimming" bathing suits was prompted by two years of research and surveys of women, age 25 to 40, who collectively complained about buying bathing suits.

In the dressing room, women are mercilessly self-critical, says Balit. "You always zoom in on your worst feature. You forget that you have a pretty smile, a pretty waist," she says. "Women are always looking at where the elastic meets the skin -- and you always see a bulge there. Women will always check their profile in the mirror and say, 'Oh, my God. Look at my stomach!' "

It's been the butt of humor in Cathy cartoons and Erma Bombeck books, but some say the problem of finding a bathing suit is more profound than body fat. "It's not a joke," says psychologist Rita Freedman, author of Beauty Bound, a 1985 book about the role of physical attractiveness in a woman's life. "Even women who are underweight, or just three pounds overweight, are tormented that they are not thin enough," says Freedman.

An upcoming vacation to the beach, says Freedman, can terrify even a secure woman. Freedman, currently writing a book called Body Love, to be released next fall, specializes in helping people become more accepting of their looks. For women who are self-conscious about wearing a bathing suit in public, Freedman suggests "a lot of fantasy and imagery." She tells a patient to "visualize herself in the situation -- on vacation on the beach -- and then rehearse positive self-statements." According to Freedman, these reassuring thoughts might go something like: "I am a beautiful woman even though I am not as thin as other women might think I should be. I am the right shape for my body. It's appropriate for women to have more fat on their bodies than men do. I don't want to be tormented by chronic dieting. Things are functioning well in my life."

The point, says Freedman: "She concentrates that she has a much broader life than those 5 minutes when she's walking on the beach in a bathing suit." Movies, magazines and television are constantly showing us beach scenes, says Freedman, "but life doesn't take place on a beach. We have become, somehow, hyperfocused on it.

"I think women should pay attention to how often they are bombarded by these images. The Sports Illustrated bathing suit issue is an excuse for a centerfold display. ... It's not really the suits that are the focus. It's not pornography. It's a well-mannered way of splashing the female body across the page.

"But it does a disservice to women who don't look that way, and it makes them feel less satisfied with themselves when they go into a dressing room and have to put on a bathing suit."

Freedman also recommends that women not become obsessed with finding the perfect bathing suit: "Don't try on a million things. Don't dwell on it. If it looks okay, then buy it and move on with your life. We have better things to do ... "