The fanciful lines and vibrant colors that characterized American postwar printmaking flowed out of a period of darkness.

“The Pull of Experiment: Postwar American Printmaking,” which officially opens this Friday at the Yale University Art Gallery, features 42 prints, including many recently donated items from James Heald II ’49 as well as works from Yale’s permanent collection. Prints by household names like Jackson Pollock and Louise Nevelson are displayed along with artworks by a variety of lesser-known artists, all of whom were active in the United States during the two decades after World War II.

The prints are divided into four thematic groups — to express, to challenge, to liberate, to question — and each represents the varied objectives of the artists. “To Challenge,” for example, shows how artists like Mauricio Lasansky and Gabor Peterdi used varied techniques to emphasize texture in their prints, an affront to the mass production employed by other printmakers at the time.

Although the postwar period has been closely examined in fields like painting, exhibit curator Katherine Alcauskas said she wanted to highlight this important stage in printmaking, which in some ways presages the abstract expressionist movement.

Following the horrors of World War II, there was a flourishing of creativity in American printmaking, marking a “pivotal” stage in the development of the medium, said Alcauskas, the Florence B. Selden fellow of the gallery’s Department of Prints, Drawings, and Photographs.

“Something that was very destructive caused this bountiful period of printmaking,” she said.

Printmakers in America after World War II used a variety of techniques, often simultaneously, which ranged from simple relief printing to the more complex intaglio printing, which involves cutting grooves into a plate and filling them with ink. The resultant prints in the exhibit often feature raised surfaces, whimsical lines and inks that seem to have bled across the paper.

While the complexities of intaglio printmaking defies description, part of the exhibit displays the tools and an original intaglio plate by Gabor Peterdi, an artist who taught at Yale for nearly three decades.

One artist whose work emphasizes such innovation was Stanley William Hayter, a British artist active in the United States during the 1940s. His print “Five Characters” combines relief, intaglio and planographic printing, and the composition is awash with turquoise, magenta and gold; narrow black lines and grooves merge with raised blank shapes, making it clear that such a print could only have been made through the convergence of multiple printing techniques.

The postwar art movement was very much influenced by the presence of European artists, such as Hayter, who came to the United States, marking an important “moment of transition” that set the foundation for later American artists, said Tatsiana Zhurauliova GRD ’13, a third-year doctoral student studying 20th-century American art.

“The way that this generation experimented really freed the field of printmaking for artists who came afterwards,” Alcauskas said.

While the Department of Prints, Drawings and Photographs has had a large variety of shows over time, the “Pull of Experiment” exhibition highlights an era not featured by the department in recent years, said Suzanne Boorsch, the Robert L. Solley Curator of Prints, Drawings, and Photographs at the gallery. The show was largely made possible by Heald’s donations, she said, adding that Alcasukas was able to bring in additional objects such as the original Peterdi plate to complement the prints from Heald and Yale’s collections.

“The Pull of Experiment: Postwar American Printmaking” is open on the fourth floor of the Yale University Art Gallery from now until Jan. 3, 2010.