The title of “Unseen Picasso,” a new exhibition opening Sept. 3 at the Norton Simon Museum in Pasadena, Calif., might sound like a tall order. Few artists are as ubiquitous as Pablo Picasso, who created tens of thousands of works and remains the world’s top-grossing artist at auction. A high-profile art sale at Sotheby’s in Las Vegas in October includes Picasso works expected to bring in at least $70 million. The Norton Simon itself has around 800 Picasso prints in its collection.

But as “Unseen Picasso” makes clear, not all prints are created equal. Curator Gloria Williams Sander has chosen a small number of works with characteristics making them “rare or unique,” including the artist’s handwritten notes to the printer, personal dedications and experiments with color. And she has included excerpts of “Suite 347,” a rarely seen magnum opus that Picasso produced in his late 80s, which offers a kind of summing up of themes and influences over his whole creative life.

Unlike many artists, Picasso had no need to rely on printmaking for profit. By 1930, the date of the first print in the exhibition, his paintings and sculptures had cemented his reputation. But to Picasso, prints were “a form of expression that he couldn’t let go of,” says Ms. Sander, adding that printmaking gave the artist “an arena to really expand himself technically.” Unlike painting, where the final image generally hides the earlier versions, prints can be made at different stages in a work’s development, preserving a record of its evolution.

The figures in the etching “Two Nude Women II” (1930) have touches of Picasso’s typical distorting style—one woman has a large back and too-small head, the other sits in a twisted, physically unlikely posture. Before printing the entire run, the printers gave the artist proofs, and Picasso chose the Norton Simon copy as bon à tirer, French for “good to print”—the ideal version of what he was looking for. In red ink, he added 1931, the year of the print run, in Roman numerals—a habit of the artist’s at the time, Ms. Sander says, that may suggest his ambition to fashion a place for himself in the millennia of art history.

“Head of Woman, No. 3 (Dora Maar)” appears in two versions in the exhibition, showing that sometimes Picasso couldn’t let go of earlier drafts of an image. Made in 1939, the print is seen by critics as expressing Picasso’s turbulent feelings in a year of personal and public tragedies: The artist’s mother died, the Republican side he supported lost the Spanish Civil War, and World War II was just over the horizon. For this work, the artist used a scraper on copperplate with determined strength, creating a print with a range of tone similar to watercolor. In the first version or “state,” he uses a blue tint and creates cross-hatching that darkly emphasizes the contours of Maar’s face and her rivulet-like hair. In the black-and-white seventh state, he has filled in the background, giving the portrait a 3-D feel. Picasso marked both prints with a note that he wanted to keep them for himself.

All of these changes and experiments could drive Picasso’s printers crazy. Today, the lithograph “The Dove” (1949) is one of the artist’s most famous images, partly because it was used on a poster for the Paris Peace Congress that year. Françoise Gilot, Picasso’s romantic partner of the time, wrote in her memoir about the image’s chaotic birth. Picasso’s printer, Fernand Mourlot, protested that his decision to paint the dove in white gouache over black lithographic ink was technically challenging. “How do you expect us to print that? It’s not possible,” he declared. Picasso asked Mourlot to give the job to Gaston Tutin, one of his most experienced printers; Gilot recalled that Tutin was even more hostile, but he did the job perfectly. The Norton Simon’s bon à tirer proof carries a dedication to Mourlot.

Picasso’s love affair with printing outlasted his many mistresses. In 1968, at the age of 86, he devoted himself for almost seven months to “Suite 347,” a series of 347 prints employing many of the techniques that he’d used over the decades. Circus performers, musketeers, childhood toys and images referencing beloved artists like Rembrandt and Raphael reappear in a diary-like record of the artist’s lifetime obsessions. Prints like these were basically “my way of writing fiction,” Picasso told photographer Roberto Otero, who wrote a memoir of the painter’s last years, “Forever Picasso.”

“Unseen Picasso” includes the Norton Simon’s copy of the first print in the suite, “Picasso, His Work, and His Public,” which shows the artist facing a circus performer in the costume of an earlier era, recalling some of his famous early paintings. A bareback rider cavorts in the background, with a wall full of eerie faces behind her representing the public. Picasso drew himself as he was: short, with wrinkled cheeks. He was always clear-eyed.