After 77 years of mystery, researchers have finally identified the vibrant turquoise pigment used in one of Jackson Pollock's most celebrated paintings. A team led by chemist Alexander Heyer from Stanford University has determined that the striking blue paint in Pollock's "Number 1A, 1948" contains manganese blue, a toxic pigment that has since been banned from commercial use.
The painting represents a classic example of Pollock's revolutionary "action painting" style, featuring black and white paint scattered across an 8.7-foot canvas, punctuated by bright drips and splashes of primary colors. This masterpiece was among the first works where Pollock abandoned traditional easel painting, instead laying his canvas flat on the floor to drip paint from above. This groundbreaking technique created a raw, expressive, and complex visual effect that directly reflected Pollock's physical engagement with and rebellion against conventional painting methods.
During this period, Pollock was deliberately breaking all established painting rules by mixing artist-quality oil paints with industrially produced enamel house paints. His unconventional approach included using brushes in some areas while making other marks by hand, squeezing paint directly from tubes, and pouring it from cans. This chaotic combination of materials and methods, combined with damage from a 1958 fire in a Museum of Modern Art gallery near where the painting was stored, created significant challenges for researchers attempting to identify the mysterious blue pigment.
"While past work has identified the red and yellow pigments that form part of his core palette, the vibrant blue in the painting has remained unassigned," Heyer and his team explained in their research. Previous attempts to identify the pigment using standard Raman spectroscopy had proven unsuccessful, leaving art historians and chemists puzzled about the paint's composition.
The research team carefully collected scrapings from the painting's blue streaks for laboratory analysis. They suspected the blue pigment might be manganese blue (barium manganate sulfate, or PB33), a synthetic pigment that was developed in 1907 but only became commercially available to artists in the 1930s. This timeline meant it would have been an exciting new color option when Pollock created his painting in 1948.
Earlier non-invasive tests conducted at a high-energy laser line of 532 nanometers had yielded inconclusive results due to fluorescence interference from the paint's oil-based binding medium. However, the Stanford team achieved success by using a different approach, comparing the paint scrapings with known Raman spectra for manganese blue collected at a lower energy line of 785 nanometers.
The scientists discovered that two distinct bands of electronic transitions give manganese blue its unique ability to filter non-blue light on either side of the spectrum. The gap between these bands reflects an exceptionally pure blue color back to the viewer's eye. "Manganese blue accomplishes a difficult task: creating clean hues from colors in the center of the visible spectrum," the researchers noted in their findings.
This discovery expands understanding of Pollock's color palette, which previously included ultramarine, phthalocyanine blue, cerulean blue, cobalt blue, and Prussian blue. The identification of manganese blue adds another layer to the complexity of Pollock's material choices and artistic innovations.
Manganese blue's powerful visual effect is no longer available to contemporary artists due to health and environmental concerns related to its toxicity. However, chemists have been working to develop safer alternatives that provide similar vibrancy without the associated risks. In 2009, researchers discovered YInMn blue, the first new blue pigment in 200 years, which artists have embraced as a substitute for toxic blues like manganese blue.
"It's really interesting to understand where some striking color comes from on a molecular level," commented Stanford chemist Edward Solomon. The team's detailed analysis of manganese blue's Raman spectrum features could help chemists develop even more stable and safe alternatives to the now-forbidden pigment, benefiting both art conservation and contemporary artistic practice.
The research, published in the Proceedings of the National Academy of Sciences, not only solves a long-standing art historical mystery but also contributes valuable scientific knowledge that could aid in both art preservation and the development of new, safer pigments for future generations of artists.
