"The Quaker," an Andrew Wyeth reproduction of questionable value is being sold through mails by Thomas P. F. Hoving, former director of New York's Metropolitan Museum of Art.

"The price? Amazingly, just $155," writes Hoving in a six-page "Dear Collector" letter he has sent to persons on a mailing list provided by American Express.

"This excellent print," writed Hoving of the framed reproduction, is an "incredible investment." "Have your local art gallery or museum appraise it," he suggests.

"I wouldn't call it an 'excellent print," said Andrew Robinson of the National Gallery of Art. "To me it's worth just pennies," said John Wilmerding, the Gallery's curator of American art.

Other curators, here and in New York, say Hoving's letter blurs the traditional distinction between photo-mechanical reproductions, whose value is largely decorative, and the prints that art museums study and collect.

"The letter is embarrassing and distressing," said one of Hoving's former colleagues at the Met. "Lo, how the mightly have fallen. Tom ought to know better."

"The Quaker" is being published by Manhattan's Triton Press.

Most print curators and collectors, for lack of a better word, call some prints "original." The term is frequently applied to lithographs or etchings, woodcuts or engravings, that an artist made or signed. The Wyeth reproduction are pictures of another sort.

Though they do have this approval Wyeth did not print them nor did he take the photograph from which they're being made. The edition is not numbered - thousands may be printed, depending on demand - and the reproductions are not signe, except in the plate.

"Our marketing is just like that of the Franklin Mint's," said Triton's Harry Lerner. "The Quarker' is a colloytpe of high quality. The reproduction is first-rate."

The Hoving letter, which he signed "Director Emertitus, The Metropolitan Museum of Art," was called "tacky in the extreme" by an official spokesman at the Met. "I promise you," said John Ross, "we had nothing to do with it."

Andrew Robinson, curator of prints at the National Gallery and president of the Print Council of America, said that he was less disturbed by the letter's prose - "a great masterpiece, masterfully recreated" - than by its implications.

"For years we've tried to teach the public about photo-mechanical reproductions. The word 'print' is imprecise - a poster is a print, so is a Rembrandt etching, but there is a difference. The National Gallery would not accept the Wyeth reproduction were it offered as a gift."

"I had to sit down! I was so impressed!" writes Hoving. "Hang THE QUAKER in your home . . ."

It's not north much more than th paper it's printed on," said John Wilmerding the National Gallery's curator of American are. "I'm not speaking of its decorative value. It might be worth something to an interior decorator."

Hoving, a medievalist, has opened a consulting firm, "Hoving Associates," since leaving the Metropolitan on Jan. 1.

"The Quaker" shows two empty coats hanging from a mantelpiece in an empty room. Both the 1975 tempera and it's reproduction rights are owned by owned by movie producer Joseph E. Levine. Levine's share of the profits will go to charity, said Lerner. Hoving declined to say how much he will be paid.

"I'm no longer a public figure. In the world of business you can keep such matters to yourself," said Hovings. He said he "definitely" would sell other photo-mechanical reproductions "if their quality was as high as this one's."

Though Wyeth is displeased by posters of his paintings sold for a few dollars in museum shops, he has approved Triton's collotype reproductions. "For years now, I have been disappointed with reproduction of my work that have been pu ton market without my approval," Wyeth writes.

"The Quaker," which is being offered under a six-month money-back guarantee, comes already framed does not include, however, the usual protecting pane of glass or Plexiglas. "You don't need it," says Lerner.

"The print is coated. You can wipe it clean with a damp cloth."