If only a few plates are issued, however, they generate little interest because only a few people know about them. Whether an artist is still living doesn't affect a plate's value, and individually signed plates aren't worth much more than unsigned ones. The material a plate is made from does affect its value. Broad themes appeal to broad markets. Popular themes for plates include holidays, cartoons, animals, flora, children, dolls, movies, sports, television, fairy tales, ethnic, historical, transportation, science fiction, fantasy, and music.
Plates commemorating an important or historical event are also timeless.
Complete sets of plates in a series aren't automatically worth more than the individual ones combined. Often more individual plates are sold because collectors are looking to fill gaps in their collections. Many plates are produced as editions in a series. For example, a manufacturer may produce a four-plate series, issuing one plate at a time. Collectors like to own an entire series and will tend to buy all four plates even if they don't like one of the editions.