One of the bright colors for which Ellsworth Kelly is known contrasts the more muted palette of his 1976 prints in “Colored Paper Image VII (Yellow Curve
with Gray).”

Ellsworth Kelly is a hard-edged man. The 89-year-old American abstractionist’s paintings feature hard geometric forms and stark single-color blocks. But Kelly took a more fluid approach for “Color Paper Images,” now on display at the National Gallery of Art. In these large-scale works, the shapes blur and the hues bleed.

“The bleeding is a big surprise,” says Charles Ritchie, the museum’s assistant curator of modern prints and drawings. “He never did anything else so free and dramatic.”

The 23 images are not works on paper, but works of paper. The colored areas are dyed pulp, pressed into freshly made, still-wet sheets until the two fused. The technique, inspired by traditional Japanese papermaking, rendered each version of the same image a little different.

“You’d call them prints, because they’re made using a press,” Ritchie says. “But they’re a mixture of a lot of different things. They’re related to collage, in a way.

“They’re a wonderful little cul de sac in his work,” he adds.

The museum acquired the set in 1980, three years after Kelly unveiled it, but had never found an opportunity to show it. That finally arrived last month after Kelly’s 18-canvas, 54-by-90-foot “Color Panels for a Large Wall” was temporarily removed from the East Building atrium because of renovation work.

“Those came down, and these went in,” Ritchie says. “We wanted to keep Kelly on view.”

With their bold forms and bright colors, Kelly’s works straddle abstract expressionism and pop art — both utterly American styles. After serving in World War II, the artist studied art in France, where he was friendly with surrealists such as German-French sculptor and painter Jean Arp. After Kelly’s 1954 return to New York, his work was criticized as too European.

In “Color Paper Images,” Ritchie says, the artist “lets his love of the surrealist accident come through in a big way. It was kind of a freeing of himself. The process sort of forced him into letting go.”

The prints were sold separately, but the curator thinks they look best as a group. “There are so many conversations going on in there between the different shapes and the different colors,” Ritchie says.

While clearly visually related to the artist’s better-known work, the 23 prints have a distinctive vibe.

“Here is something that is soft, even atmospheric,” Ritchie says. “I can’t think of any other Kelly works that are as inviting in the same way.”

National Gallery of Art, 4th Street and Constitution Avenue NW; through May 19, free; 202-737-4215. (Archives)