Color consultant Leatrice Eiseman talks about walking into a Los Angeles salad bar restaurant, looking around and thinking that the place probably wouldn`t last too long.

''It was a beautiful salad bar, they had everything (for salads),'' she said. ''But the main color was a strong yellow-green and that`s a color we associate with nausea. If a restaurant uses a green that`s the color of healthy spinach, that`s fine. But a yellow-green gives the feeling of slime and ooze.''

Sure enough, the restaurant closed within a short time.

And although the closing sign didn`t say ''We Used the Wrong Colors,''

chances are that Eiseman`s assessment that the color choice jeopardized the restaurant`s success was at least partially right.

The psychological effect of colors used in a restaurant is critical. Although you, the diner, probably never consciously sit at your table and think ''these colors make me want to order everything from the menu,'' you can be assured that a successful restaurant owner and/or designer has given a lot of thought on color and how they want it to affect you.

Are they looking for rapid table turnover, or diners who linger over afterdinner drinks? Do they want you to go away thinking ''that was fun,'' or leave thinking ''how romantic''? Is it a vegetarian-oriented spot or heavy on the meat?

''R.J. Grunts was woody and homey. I wanted it to feel very comfortable and not jarring at all,'' said Richard Melman, president of Lettuce Entertain You Enterprises, referring to the first restaurant he opened, in 1971. ''At Eccentric, we must have tried five different colors on one wall before we got the cream color that gave the clubby feeling we wanted.''

''We know that some colors stimulate the appetite and some colors turn people off totally when it comes to food,'' Eiseman said during a recent telephone interview. Eiseman heads the Eiseman Center for Color Information and Training in Seabeck, Wash., and has spoken in Chicago at the National Restaurant Association annual show.

For example, fast food places that want you to order that double-everything and not linger ''use a lot of orange, yellow and red; those warm colors are stimulating,'' she said. ''But if you`re talking about a fine restaurant where you want people to linger, you`d use subtler, high class variations of orange . . . peach, apricot and cream, colors that engender softness and warmth.''

The old rule of thumb that red was the best color for restaurants and

''you never use blue'' is completely gone, according to Mark Knauer, who has designed such restaurants as Trattoria No. 10 and Old Carolina Crab House and was recently working on Tuttaposto, a Mediterranean restaurant that opens Friday in River North.

''All the taboos of the past are blown out the window now,'' he said.

''You can do almost anything with color, as long as it`s appropriate and has warmth and doesn`t turn you off. . . . At Tuttaposto, we`re using about eight colors, over twice what`s usually traditional. When you look at pictures of the Mediterranean, you see all this deep blue of the sea, the colors of the boats, then all the colors of the buildings, and that`s the story we`re telling.

''We can do that now because the industry has become much more sophisticated.''

That old rule of red referred to by Knauer, however, still is appropriate in many restaurants, such as Italian and Mexican, according to Eiseman.

''Your expectation when you go into that (Mexican or Italian) is (for red), and you can only really change that in an upscale restaurant where you have upscale customers who are intrigued with breaking that kind of tradition,'' she said.

Whereas off-white or cream walls are usually very restful, white walls might give a good case of the jitters-and make the customer just want to leave. ''White can be very stark, and it gets too stark if you`re sitting there for any length of time,'' Eiseman said. ''Also, if you`re eating something red, say cherry pie, and you look at the red and then look at those white walls, the after-image is going to be green. Not good.''

Although we tend to think of walls, dishes, napkins and the like when we think of color in restaurants, it`s the color of lighting that is particularly crucial, say experts.

All women know that soft lighting is kinder to the skin, and restaurateurs know it`s also kinder to food.

''Lighting is the important thing, you stay away from blue and green

(lighting). Lights should be peachy, off-white,'' Melman said.

''Light is what makes food look good or not look good. Any sort of blue or green light is going to make food look unappetizing,'' agreed Knauer.

''Shades of yellow gives food a warm feeling.''

And if you notice the color of the plate, that may be a bad sign.

''I`m a purist,'' Melman said. ''I like plain white plates; a plate should be the frame for the food.''

Is there a trend for the future when it comes to color?

The biggest trend is the elimination of trends-or, as Knauer said, throwing the old rules out the window. There`s also a trend against fads; fad colors can quickly date a restaurant and it`s too expensive to redo interiors. ''There just is no definitive color palette as there was for so many years,'' Eiseman said. ''A couple of decades ago, we were awash in avocado gold and rust. In the 80s, there was the mauving of America, mixed with gray. All that dates a place, an atmosphere.

''What I see is a lot of wood coming back, faux granite and marble, which give a classic feeling. The accent colors of table linens, posters, those sorts of things can be easily changed.''