Quest to crack blues mystery in Pollock painting reveals colour-tuning technique

Jackson Pollock’s Number 1A, 1948 is one of the most famous examples of action painting, where paint is dripped, splashed, and layered onto a surface. While art historians and scientists had years ago identified the reds and the yellows in this canvas to be cadmium pigments, the provenance of the striking blue that threaded through the work remained unclear.

This lacuna wasn’t just a matter of curiosity. Knowing exactly which pigments Pollock used could help authenticate his paintings and help preserve them. Beyond art history, the blue itself — known among chemists as manganese blue — is a pigment with unusual properties. Once popular in the mid-20th century but later banned from production, it stood out because of its pure blue hue and chemical stability. So scientists were motivated to ask what gives manganese blue its colour and whether Pollock had really used it in this landmark painting.

Answering these questions required combining chemistry, physics, and art conservation in a way that bridged the laboratory and the museum — and this is what scholars from the US, including the Museum of Modern Art in New York, have reported doing in a September 15 paper in Proceedings of the National Academy of Sciences. While confirming that the blue is indeed from manganese blue, they found a way for scientists to ‘adjust’ the colours of inorganic pigments.

The research team used a set of advanced tools that probed how light interacts with matter. In particular, they used resonance Raman spectroscopy, which measured the vibrations of molecules when light excited them to identify whether the pigment was indeed manganese blue. To explore how the pigment created its blue colour, they added magnetic circular dichroism spectroscopy, which detected how magnetic fields affected the way molecules absorb light, and compared these results with density functional theory (DFT), a type of computer modelling of electronic structure.

By combining these approaches, the researchers could map the small electronic transitions inside the pigment — the jumps of electrons between energy levels — that determined which colours of light were absorbed and which were reflected. The team also tested the blue passages in Number 1A, 1948 directly with Raman spectroscopy to settle once and for all what Pollock had put on his canvas.

The spectroscopic evidence confirmed that the blue pigment in Pollock’s painting was manganese blue. At the molecular level, the colour was found to come from charge-transfer bands: when electrons moved from oxygen atoms to the manganese atom, light of certain energies was absorbed. Normally, such transitions produce muddier colours. But here, the exchange of electrons in certain orbitals absorbed, and thus filtered out, green and violet light while letting blue light through.

This result is significant for many reasons. In art, confirming manganese blue in Number 1A, 1948 will help conservators plan restoration work and give scholars more evidence of Pollock’s materials and choices. It could also open the possibility of identifying the same pigment in other works by Pollock and his contemporaries, like Willem de Kooning, who was also said to favour it. For scientists, the researchers wrote, the study shows that inorganic pigments can be tuned by adjusting the arrangement of other atoms around a metal atom, thus altering its electrons’ energy levels. This could inspire the design of new pigments or optical materials, perhaps even for use in technologies like lasers.

Finally, according to the paper, the findings offer a reminder that art and science aren’t separate worlds. A question born in front of a canvas — “what blue is this?” — led to deeper insights into how matter and light interact, showing how creativity and chemistry work together.

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