IN 1981, shortly after he was named a stamp design coordinator for the Postal Service, Howard Paine told an interviewer he wanted to do "some adventurous things" with stamps. "I'd like to see some of the great caricaturists design stamps. Al Hirschfeld could do theater people . . . "

Change often comes slowly to the Postal Service and it took 10 years for Hirschfeld to do his first stamps. But his 1991 booklet of stamps honoring five comedians was such a hit that the New York artist has been brought back for an encore.

This time Hirschfeld drew 10 stars of the silent screen, and Paine, who again is overseeing the stamps, suspects it won't be the last time that the renowned caricaturist produces stamps. After all, he pointed out, Hirschfeld has drawn more than two dozen entertainment personalities for the Postal Service. Some of the remaining designs are certain to be released either individually or as a third set of stamps, Paine said.

Hirschfeld's silent screen stamps go on sale April 27 in San Francisco on the eve of the city's international film festival. As in his first set, the artist has hidden the name of his daughter, Nina, in the stamps, thus retaining his distinction as the only artist who has been permitted to place a hidden mark on a U.S. stamp.

As Paine explained in an interview last week, former postmaster general Anthony M. Frank was so firmly convinced that Hirschfeld's "Ninas" had to be a part of the comedians' designs that he directed the artist "to add as many Ninas to all the stamps as you can." Hirschfeld put one in four of the five comedian stamps.

Postal officials are not saying how many Ninas are in the 10 new stamps. "It's up to the collector to guess how many," the service said in its announcement of the new set.

But a quick inspection of photographs supplied by the Postal Service indicates they are hidden, for certain, in the dresses of Clara Bow and Zasu Pitts, the baggy trousers of Charlie Chaplin and the bow tie of John Gilbert, perhaps tucked in the shoulder of Rudolph Valentino and the stringy hair of Lon Chaney, and not in the sketches of Theda Bara, Buster Keaton, the Keystone Cops and Harold Lloyd.

Because the stamps also carry the names of the stars and a torn ticket stub that contains the stamp's 29-cent price, Paine said it proved impossible to have a Nina in every stamp. Both the purple type and red ticket stub that were used in the comedians' stamps reappear in these stamps, elements that Paine said will give them "a touch of color and a touch of the theater."

Despite his desire to approach Hirschfeld, Paine said he did not talk to the artist about stamp designs until 1987 after postal officials had decided to honor Stan Laurel and Oliver Hardy. That stamp ultimately grew into the comedians booklet.

The silent screen stamps are being produced in sheets of 20 by the Bureau of Engraving and Printing using a combination of offset and intaglio printing. Only the names and theater tickets were printed by intaglio, in part because Paine said he did not want to have an engraver attempt to trace Hirschfeld's design.

"There is a danger in having someone else try to draw Hirschfeld," he said. Early on, Hirschfeld offered designs in color, but Paine rejected them as lacking the sharpness and clarity of his newspaper drawing.

As members of the Citizens Stamp Advisory Committee reviewed the drawings, there was much debate over which stars from the silent movie era should be honored, according to Paine. Some members of the committee also expressed concern that some of the stars would not be well known to many young stamp purchasers, he said. To help solve that problem, the Postal Service has printed a 56-page book about the stars on the stamps. It sells for $24.95 including a sheet of the stamps and will be available from philatelic sales windows at major post offices.

Paine said Hirschfeld, now 90, "is having a ball with this." Although his drawings command more than the standard $3,000-a-stamp fee paid by the Postal Service, he did the work for that price, willingly modifying his designs to fit the formats needed for stamps. Of course, Paine noted, the artist shipped his modifications back to the Postal Service by Express Mail.

THE MINT'S new Citizens Commemorative Coin Advisory Committee is seeking ideas on what subjects should be on the nation's coins between 1995 and 1999. The panel is due to report to Congress by December and it wants ideas -- "100 words or less" -- by June 20.

Subjects may include "notable persons, events, buildings, institutions, etc.," the Mint said. It is discouraging any "regional and local themes," preferring national and international themes. Ideas should be "both interesting and educational." If commemorating an anniversary, it should "date back at least 50 years," the Mint said. Ideas should be mailed to Commemorative Coin Themes, P.O. Box 350, Conshohocken, PA 19428.

INDIVIDUALS wishing first-day cancellations of the Silent Screen Stars should send self-addressed envelopes carrying the stamps to: Customer-Affixed Stamps, Silent Screen Stars, Postmaster, San Francisco, CA 94188-9991. Requests should be postmarked by May 27.

Bill McAllister is a member of The Washington Post national staff.