Artists, curators and dealers yesterday expressed surprise at the record auction price for a Washington Color painting -- $300,000 -- set Thursday in the Manhattan salesrooms of Sotheby Parke Bernet. Among the people most astonished was Color painter Kenneth Noland -- who made the work in question here 21 years ago.

"God Almighty," Noland said yesterday when he learned that "Empyrean," his concentric-circle painting, is now the most expensive canvas by a living American artist ever sold at auction. "It's kind of embarrassing," he added from his home in southern Florida. "I don't know what it means."

The $300,000 "hammer price" more than doubled the auctioneer's presale estimate of between $90,000 and $120,000. Because Sotheby's exacts a 10 percent "buyer's premium," the stained acrylic painting -- a 6-foot-9-inch square, sold by the estate of Mrs. William H. Weintraub of Westhampton, Long Island -- actually cost its purchaser, a Denver collector, $330,000.

Two other Washington Color paintings by the late Morris Louis, both from the same estate, also fetched high prices at the evening auction. One, a 1961 stripe painting called "Sky Opening," brought $250,000, a new record for Louis. The other, a 1958 "Floral," sold for $220,000.

The prices fetched by both "Empyrean" and "Sky Opening" exceeded the previous auction high for a living artist's picture, the $240,000 obtained at Sotheby's nine years ago for "Double White Map" by Jasper Johns. Pictures traded privately may well have brought more. The shahbanou of Iran is reported to have spent $2 million for a picture by Willem de Kooning, and one New York museum is said to have paid $1 million for a work by Johns, but such figures are not certain.

"I have no idea why 'Empyrean' brought so much," said Noland. "Maybe scarcity had something to do with it. My early circle paintings are not often on the market. It is not as if the prices of my paintings have kept pace with, say, those of the Pop artists. I'm not a celebrity. I think of myself as kind of anonymous -- and certainly not famous."

Noland, who received nothing from the sale, said, "That's all right. Somebody bought it. I was paid. I used the money to paint more paintings."

There is a chance, of course, that the $300,000 sale might have been a fluke. Two other works by Noland, one from 1960 and one from 1969, were also in the auction. The unusual 1960 picture, with its curving colored stripes, brought $25,000. The 1969 painting, which is 8 feet long but only 6 inches high, sold for $9,700.

"Empyrean" is the kind of Noland canvas cited by those scholars who contend that he helped alter America's art history. Although its "target" format suggests Euclidean rigor, its outside rings are painted with extraordinary freedom. It is a work of art that seems to bridge the gap between the anxious Action paintings of the 1950s and the bigger, cooler and more colorful works that were to come.

"What surprises me about the sale," said E.A. Carmean, curator of 20th-century art at the National Gallery of Art, "is not that a Noland circle painting achieved so high a price, but that it has reached it so quickly."

Noland, who was born in Asheville, N.C., in 1924, moved to Washington in 1949 and lived here until 1962. He studied the city's museums and mastered his profession here (his former wife Cornelia, runs Alexandria's Nuevo Mundo; his son, William, is now showing his bronze sculptures at the Addison-Ripley Gallery behind the Phillips Collection where Kenneth Noland imitated the Klees). During his first years in Washington, Noland taught at Catholic University (where the late Howard Mehring, another Washington Color painter, was among his students) and at Leon and Ida Berkowitz's Washington Workshop Center for the Arts. It was at the Workshop Center that he met Morris Louis. The two men soon became "painting buddies" and close friends.

There is no doubt that the two of them were among the prime initiators of the Washington Color School, but that "School" had other members, among them Gene Davis, Howard Mehring, Tom Downing and Paul Reed. All these abstract painters used hard edges, strict geometries and flat uninflected areas of stained acrylic color.

Though fine stripe paintings by Davis may sell today for $30,000, the best Mehrings and Downings, splendid though they are, fetch a third as much. Though matters of quality and primacy do affect market value, the price discrepancies between a $300,000 Noland or a $250,000 Louis and a $5,000 Downing are not easily explained.

Fashion has something to do with it; so, too, does promotion. Both Noland and Louis were championed, most effectively by a highly influential critic, the writer Clement Greenberg. Noland's circle paintings were shown, in 1959, in a one-man exhibition at French and Co. in New York. Greenberg, who the year before had become that gallery's "artistic adviser," helped choose and hang the show. The next May, in Art International, Greenberg declared Noland and Louis the two artists he considered "serious candidates for major status" among all younger American artists. Where Clement Greenberg led, many curators and critics and art dealers followed. Major monographs were published on Louis and Noland, and their prices steeply climbed.

The best canvases of Davis, Mehring and Downing have never managed to attract such important friends. No major book has yet appeared on the Washington Color School. Washington dealer Ramon Osuna, who has sold many of its paintings, said, "The Noland sale astonished me. The market for Color paintings, until Thursday, was relatively weak."

"The Washington Color School deserves study," said Gene Davis yesterday. "The record Noland price is going to help the rest of us -- for sure."