Scientists confirm manganese blue in Jackson Pollock’s 'Number 1A, 1948', solving 77-year mystery

Scientists have identified the specific blue pigment Jackson Pollock used in one of his most celebrated canvases, resolving a 77-year question about the materials behind the artist’s signature "drip" work.

A team from the Museum of Modern Art (MoMA), Stanford University and the City University of New York reported that the vibrant turquoise in Number 1A, 1948 is manganese blue, a synthetic pigment produced from the 1930s until the 1990s and largely discontinued because of environmental and health concerns. The findings, published in Proceedings of the National Academy of Sciences, mark the first confirmed identification of that pigment in a Pollock painting.

Researchers obtained tiny scrapings of the turquoise paint from the canvas and used laser-based techniques that measure molecular vibrations to generate a chemical fingerprint of the material. That fingerprint matched manganese blue, whose molecular structure produces a bright azure hue by filtering nonblue wavelengths in light, the team said. Previous pigment studies had identified reds and yellows in the work but left the blue unassigned.

Manganese blue was first synthesized in 1907 and became a widely used commercial pigment in the 20th century, including uses beyond fine art such as coloring cement for swimming pools. Production tapered off and the pigment was discontinued in the 1990s amid concerns about environmental impact and suspected toxicity. Conservation and Art Materials Encyclopedia Online notes that inhalation or ingestion of manganese blue can cause nervous system disorders.

Number 1A, 1948, an oil-and-enamel painting roughly 68 by 104 inches now held at MoMA in New York, is a quintessential example of Pollock’s action-painting, with drips, ropes of colour and layered pools of paint. Working on the floor of a converted Long Island barn, Pollock used low-viscosity commercial enamel paints and often poured or dripped directly from cans or sticks rather than mixing on a palette. The new chemical confirmation indicates he applied manganese blue in the same direct manner, consistent with his broader materials choices in the late 1940s.

The team’s analysis also examined the pigment’s chemical structure to explain its distinctive hue and to provide information relevant to future conservation. Because manganese blue is no longer commercially available and is difficult to reproduce by mixing modern paints, knowing its identity gives conservators "critical context for conserving his work," the researchers said in a statement accompanying the publication.

Art-historical context links the painting to a period when Pollock moved away from evocative titles and toward numbering his canvases; his wife, the artist Lee Krasner, described numbers as neutral, allowing viewers to "look at a painting for what it is — pure painting." Number 1A, 1948 is frequently cited as an archetype of his drip technique and of mid-20th-century abstract expressionism.

Scientific study of Pollock’s materials has expanded in recent years as conservation scientists aim to understand how commercial paints and pigment degradation affect the appearance and long-term stability of modern works. The laser-based vibrational methods used by the MoMA-Stanford-CUNY team allow non-routine pigments to be identified even when formulations are no longer produced.

The discovery does not alter the authorship or broader art-historical assessments of Pollock’s work, but it does affect practical questions about treatment and display. Conservators must weigh the pigment’s rarity and potential hazards when planning interventions, storage and exhibition lighting. Identifying an "extinct" pigment also helps curators and scientists interpret the original visual intentions of the artist and to prepare accurate reproductions for study.

Pollock's technique has attracted attention from physicists and materials scientists as well as art historians. Studies of his pouring methods have noted that his handling of fluid paints produced long, unbroken filaments and that he appeared to control fluid instabilities, such as the tendency of viscous streams to coil, in ways that contributed to the characteristic look of his canvases.

Jackson Pollock (1912–1956) remains a central figure of American abstract expressionism. Number 1A, 1948, created during a period when he emphasized process and physical engagement with the canvas, will now be understood to include a pigment that is no longer in common use, a detail that specialists say refines both the technical and visual history of the work.