Scientists Identify 'Extinct' Blue Pigment in Jackson Pollock's 'Number 1A, 1948'

A multinational team of conservators and scientists has identified the vibrant blue pigment in Jackson Pollock’s 1948 painting "Number 1A, 1948" as manganese blue, a synthetic pigment no longer widely available. The finding, published in the Proceedings of the National Academy of Sciences, provides the first confirmed chemical identification of the turquoise-blue used in one of the artist’s most celebrated action paintings and offers new information for conservators responsible for preserving his work.

Researchers from the Museum of Modern Art (MoMA), Stanford University and the City University of New York sampled tiny fragments of blue paint from the canvas and used laser-based techniques to scatter light and measure how the paint’s molecules vibrated, producing a molecular fingerprint for the color. That fingerprint matched manganese blue, a bright azure pigment first synthesized in 1907 that was produced commercially from the 1930s until it was discontinued in the 1990s amid environmental and toxicity concerns.

Manganese blue was prized for its pure, saturated hue and was used in artists’ paints and even in colored cement for swimming pools. According to the Conservation and Art Materials Encyclopedia Online, inhalation or ingestion of manganese blue can cause nervous system disorders, and concerns about its environmental and health impacts led to its decline in commercial use by the late 20th century. The pigment’s color is difficult to reproduce by mixing other paints because its molecular structure filters nonblue wavelengths in a way that fine-tunes the perceived shade.

The confirmation fills a longstanding gap in technical analyses of Pollock’s materials. Previous studies had identified reds and yellows in "Number 1A, 1948," and had suggested that the turquoise areas might be manganese blue, but the new study is the first to confirm the pigment directly from paint samples taken from the canvas.

Conservators said the identification is important because precise knowledge of an artwork’s materials informs treatment decisions and helps maintain fidelity when stabilizing or cleaning a painting. Manganese blue’s absence from modern palettes means that conservators and restorers cannot rely on off-the-shelf replacements to match its optical properties, and knowledge of the pigment can guide decisions about varnishes, adhesives and environmental controls.

The painting itself is a near 9-foot-wide example of Pollock’s drip or "action" technique, in which the artist poured and flicked liquid paint onto a canvas placed on the floor. Working in a converted Long Island barn in the late 1940s, Pollock frequently used lower-viscosity commercial enamel paints that poured and splattered differently than traditional artist oils. Technical studies of his method have noted that Pollock’s handling of fluid paint often avoided a physical phenomenon known as coiling instability, producing long filaments rather than curls.

"Number 1A, 1948" is in the collection of MoMA in New York, where it remains on display. The work features layered ropes of color, drips of black and pools of white, and includes Pollock’s handprints near the upper right. Around the time he made the painting, Pollock stopped giving his canvases evocative titles and began numbering them; his wife, artist Lee Krasner, later said that numbers were "neutral" and made viewers look at a painting for what it is.

Jackson Pollock (1912–1956) was a central figure in the abstract expressionist movement and is best known for developments in the drip technique that emphasized the physical act of painting. He died in a car crash in 1956. The new pigment identification adds to the technical record of his materials and complements ongoing research into how his choices of commercial paints and application methods contributed to the appearance and long-term behavior of his paintings.

The authors of the PNAS paper described the result as critical context for conservation planning. By establishing a chemical signature for manganese blue in Pollock’s work, the study gives conservators a factual basis for assessing past treatments, anticipating future degradation pathways related to the pigment’s chemistry, and developing tailored protocols for preservation. The researchers noted that identifying such discontinued materials also helps museums make informed decisions about display conditions and handling to minimize deterioration.

The study illustrates how modern analytical tools can resolve long-standing questions about artists’ materials. Laser-based vibrational analysis and related spectroscopic techniques have become standard in technical art history for distinguishing synthetic pigments, binders and fillers, and for tracking changes that occur as works age. In the case of "Number 1A, 1948," the tools provided a definitive answer to a 77-year-old question about the origins of one of Pollock’s most striking blues.