IF THERE HAD BEEN a New Yorker magazine 90 years ago, it would surely have used a Maurice Prendergast monotype on its cover. Prendergast loved going into the fashionable neighborhoods of Boston, London, Paris, Rome and Venice, and capturing on paper the fashionable women there -- wearing capes, cloaks, boas, muffs, wide hats and long dresses that flirt with the wind. He caught the ladies at their leisure at the races; with their children, dotting the park or the beach. White images against green grass, the children become static objects of celebration, while kites flying overhead impart action. These images of gentility feel like watercolors and focus on forms rather than substance.

Fifty-five such prints are now at the National Gallery in "Monotypes by Maurice Prendergast from the Terra Museum of American Art." Shimmering, coloryet ghostly, they show that there is nothing monochromatic and certainly nothing monotonous about monotypes.

Like Edgar Degas, Prendergast was a consummate practitioner of the process.

The monotype is made, quite simply, by applying oil or printer's ink to glass or a metal plate and pressing a piece of paper on the wet-paint image. As Prendergast explained it to a student: "Paint on copper in oils, wiping parts to be white. When picture suits you, place on it Japanese paper and either press in a press or rub with a spoon till it pleases you."

Although the word monotype refers to a single print, actually two or three "pulls" or copies are possible from the plate. Prendergast, who used a large spoon, sometimes preferred the second or third print.

The monotype gets its luminous quality from paint applied thinly or partially: the paper reflects light back at you. This explains some, but not all, of the inherent fascination of these monotypes -- you tend to keep looking, as if disbelieving. How delicate the original conception was to retain its fragile appearance through such a crude process. How delicious the faded colors: there and not there.

And Prendergast's ladies are lovely, glimpsed turning a corner or catching his gaze; holding umbrellas like the single kimonoed lady in Japanese prints that must have inspired him; then fading from view, soft edged. If the artist did them with a breezy flair, he was racing with rapidly drying paint. And the little girls in red capes, out shopping, walking deliberately alongside their mothers, also dressed alike in long black gowns and big bonnets. A mother is turning to speak to her girl -- ah, but never harshly.

Prendergast, an American, went to Paris in 1891, and his style was spontaneously ignited as he fell under the influence of the work of Whistler and Bonnard. Then, until 1902, Prendergast worked in the monotype medium and made it his own. Before he turned to oils in earnest, it's thought he made 200 monotypes in all; 151 are known. With this show from the Terra Museum of American Art in Evanston, Illinois, we see more than a third of them.

MONOTYPES BY MAURICE PRENDERGAST FROM THE TERRA MUSEUM OF AMERICAN ART -- In the National Gallery of Art's East Building, through April 14.