Ten years ago, a team of researchers began investigating the presence of beeswax in Diego Rivera’s famous mural, “La Creación.”

The ingredient was an essential component in an ancient Greek painting technique that Rivera claimed to have brought back to Mexico. 

Now, a decade later, the conclusion is all but final: There is no wax in “La Creación.”

According to one of the project’s lead researchers, Sandra Zetina Ocaña, the scientific finding is further supported by contemporaneous accounts. 

“It’s in the books,” Zetina Ocaña, an art historian specializing in materials and techniques at UNAM’s Instituto de Investigaciones Estéticas, tells me. “I’m not the one saying it; his own colleagues from that time are saying that he lied to them.” 

But the story of “La Creación” is much larger than some lie Rivera allegedly peddled to the public. 

It is a testament to the exploration of the meaning of materials in Mexican muralism and a reminder of how art and science can work together to reveal new dimensions of the creative process.

The controversial beginning of Diego’s ‘La Creación’

In the early 1920s, Rivera returned to post-revolutionary Mexico after a decade spent living in Paris. 

At the time, Mexico’s secretary of public education, José Vasconcelos, was grappling with the high level of illiteracy among the country’s populace. Eager to galvanize the education of the masses, he hired Rivera to paint a mural in the Antiguo Colegio de San Ildefonso.

The mural, “La Creación,” depicts the birth of humankind with Adam and Eve, as told in the Biblical story of “Genesis,” while also paying tribute to ancient Greek mythology. The four cardinal virtues and the nine muses who inspire creativity are symbolized with Latin American features, hinting at the cosmovision of Vasconcelos’ “Cosmic Race.” 

As models for the muses, Rivera used women emancipated during the cultural movement of post-revolutionary Mexico. “All the women portrayed are fascinating,” Zetina Ocaña says, adding that they “changed what it meant to be a woman.” 

Critics at the time praised Rivera’s playful use of proportions, claiming he “revives monumental painting not only in Mexico, but throughout the world.” Jean Charlot, a French painter who later worked in the U.S. and Mexico, said that Rivera successfully bridged Cubism and large-scale mural painting. 

Today, “La Creación” is widely considered the starting point of Mexican muralism. 

However, despite the positive reviews, Vasconcelos disliked the mural, arguing that Rivera failed to capture the Mexican spirit. 

Rivera himself later conceded that, “despite the effort to express genuine Mexican beauty in the characters, it still resists in its execution and even in its internal meaning, because of overly strong European influences.”

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Occidental influence and encaustic painting 

Rivera’s decade-long stay in Europe was not only reflected in the mural’s Byzantine iconography and Cubist style. It extended into his painting technique as well. 

Encaustic painting involves mixing beeswax with resin and pigments, and then applying heat to layer it onto a surface. It was developed by the ancient Greeks and rediscovered during the Renaissance. 

Leonardo Da Vinci reportedly tried applying the technique to a wall painting of “The Battle of Anghiari” but ultimately failed and never finished the work.

In a conversation with his fellow artist Juan O’Gorman, later published by the Colegio Nacional, Rivera discussed his use of encaustic painting in “La Creación.”

“It can truly be said that [with La Creación] true encaustic painting was restored for the first time since the Greco-Roman period,” Rivera told O’Gorman.

Going one step further, Rivera claimed that he had innovated an encaustic technique unique to Mexico by incorporating resin from the copal tree as a binding material.

Technique as an inseparable part of the image

For the next century, Rivera’s claims about the use of encaustic painting in “La Creación” went largely unchallenged.

That is, until a group of art historians and chemists at UNAM decided to look a bit deeper and perform a forensic study of the mural, hoping to identify its material aspect. To understand why, for more than a decade, a team of researchers investigated traces of beeswax in Rivera’s mural, one must understand the importance of materials in the artistic process. 

David Alfaro Siqueiros, considered one of the “three greats of muralism,” wrote in “How to Paint a Mural” that “It must not be forgotten that the materials and tools of production in the visual arts have a generative and determining value, both formally and aesthetically.”

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Zetina Ocaña similarly explained that what she finds so compelling about Mexican art in the early- to mid-20th century is its focus on thematic and material reinvention. 

Siqueiros, for example, incorporated nitrocellulose paints, originally an industrial lacquer for cars, into his murals. Besides enabling him to paint dynamic colors quickly, the use of industrial materials carried an ideological meaning as well: breaking with elitist artistic traditions and reflecting the technological progress of the time. 

Similarly, Pablo Aguilar-Rodríguez, a chemist at UNAM and the driving force behind the forensic investigation of “La Creación,” points to the work of Mexican painter and Rivera’s son-in-law, Rafael Coronel. 

According to a chemical analysis, Coronel used a type of dental filling as a binding material in his mural “Paisaje Abstracto.” 

“It is a material that was completely unrelated to that purpose, and at the time the mural was painted, it represented a major technical innovation,” Aguilar-Rodríguez says. “Understanding it from this chemical perspective tells me that Coronel innovated not only in his content, but also in his materials. Being able to understand art from that perspective seems very, very special to me. I don’t think Coronel’s intention could have been understood without this analysis.”

The forensic analysis: Where is the beeswax?

To test Rivera’s claims about the use of beeswax and copal in his mural, the research team employed an elaborate process.

Through optical, digital and electron microscopy, Zetina Ocaña meticulously examined the mural to determine which areas were best suited for further chemical analysis. Once samples were selected, they went through chromatographic analysis and nuclear magnetic resonance spectroscopy. 

Although all the samples showed traces of copal, none revealed the presence of beeswax.

While pursuing his doctorate, Aguilar-Rodríguez had developed a technique in which spectroscopy and microscopy are combined to create chemical maps of paintings, identifying polymers such as acrylics and nitrocellulose or beeswax. 

“I was able to identify beeswax very clearly in another work by Diego Rivera, ‘El Matemático,’ so I could use the samples that had already been taken from ‘La Creación’ and analyze them again using this same methodology,” Aguilar-Rodríguez says. 

But when analyzing the samples that Zetina Ocaña had sourced from “La Creación,” he, too, failed to back up Rivera’s claims.

‘As an art historian, I wanted to die’

The researchers hypothesized that the application of heat during the encaustic procedure might have eliminated any traces of beeswax. To test this, they burned beeswax samples to different degrees. But no matter how much heat they applied to the material, it was always detected in further testing. 

Next, they wanted to determine whether the beeswax had potentially degraded and been lost to time. However, after analyzing samples from other encaustic murals of Diego’s time, including those by Siqueiros and Charlot, they successfully confirmed the presence of beeswax, leaving little doubt about the truth behind “La Creación.”

“No, there isn’t any beeswax,” Aguilar-Rodríguez says. “There never was. It didn’t degrade. It simply wasn’t added in the first place.”

Zetina Ocaña says that every time she met with her team, she left with a headache.

“They would tell me, ‘There’s no wax. There’s no wax.’ And I’d say, ‘Really?’ They would look at me and say, ‘There’s no wax, Sandra,’” Zetina Ocaña says. “We would have liked to spoon-feed it a little, put a little wax in there, but no. As an art historian, I wanted to die.”

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Beyond the truth: Cultural heritage and the synergy of art and science

The question of whether Rivera used an ancient painting technique goes beyond the question of truth and the meaning of materials in the artistic process. 

It is part of a broader dialogue that centers the future of Mexico’s cultural heritage.

Cultural heritage is the conglomerate of artifacts, belief systems and traditions that define a nation’s identity and history. Mexico is particularly rich in its cultural heritage, earning the ninth spot on UNESCO’s World Heritage List. 

But time takes its toll on physical artifacts, and their conservation is becoming increasingly important.

In another study led by Aguilar-Rodríguez, Frida Kahlo’s painting “Dos Fridas” was analyzed to understand the inherent degradation process when frequently transporting the artwork for exhibition. 

The white regions painted with zinc oxide proved especially concerning, while lactic acid was found to be a significant culprit behind the artwork’s degradation. The researchers also concluded that cleaning the artwork with water might accelerate the chemical breakdown of the organic compounds.

Likewise, to understand the conservation challenges of Coronel’s “Paisaje Abstracto” and develop a proper treatment, his unknown binding material had to be identified. The dental filing material uncovered during forensic analysis paved the way for an effective conservation strategy. 

‘A historian’s dream’

Dr. María de las Mercedes Sierra Kehoe, an art historian and postgraduate faculty member at UNAM, highlighted the beauty of bridging art and science. 

Mercedes Sierra Kehoe is part of a multidisciplinary research team that includes art historians, conservation specialists and scientists working within the National Laboratory for Research and Conservation of Cultural Heritage (LANCIC). 

She and her colleagues analyzed Rivera’s “Sueño de una tarde dominical en la Alameda Central” using various techniques like X-ray fluorescence, infrared spectroscopy, Raman spectroscopy and reflectance spectroscopy to identify the pigments and materials that make up the mural’s color palette.

“Bringing the humanities and science together has allowed us to discover and recognize elements, processes and projects that would not have been possible to uncover without these instruments,” Mercedes Sierra Kehoe tells me. “It is a historian’s dream.” 

Without practical applications, though, scientific discoveries risk losing their salience.

“I always praise the work of my colleagues in conservation,” Mercedes Sierra Kehoe says. “They are heroes without capes, because ultimately they are responsible for ensuring that our historical heritage endures.”

Deliberate deception or something more innocent?

Despite the recent scientific revelations behind “La Creación,” one question remains: Why would Diego Rivera misrepresent the techniques he used in its composition? 

“He is a very talented artist, but he is a very erudite artist — an artist who studied a lot, who practiced a lot, who researched a lot,” Zetina Ocaña says. “What is true is that he had painted with wax, because we have a beautiful painting which he presented at an Autumn Salon as an encaustic wax painting.”

According to Zetina Ocaña, Rivera may not have been trying to intentionally dupe the public at all. Rather, it might’ve been a case of timing and the painter merely getting ahead of himself.

“He hadn’t even started painting yet, and they were already publishing an article about him in the newspaper,” Zetina Ocaña explains. “And that’s where he says he’s going to use wax, the encaustic technique.”

Mercedes Sierra Kehoe offers another explanation. 

“A very important part of Diego Rivera is that we have to understand that he was a great painter who understood the art market — he knew how to sell himself, he knew how to work the media,” she explains.  “So it’s not that the artist lied, right? At that moment it was his own reality, and that’s how he wrote it.”

Or, maybe, he was simply lying. 

Much like a chef who doesn’t want to reveal his secret recipe, or an inventor working on a patent, Zetina Ocaña explains, Rivera was known to have lied about his painting techniques, a deliberate deception to hide his artistic process and “a particular way of making something that is very personal.” 

Whatever the reason, Zetina Ocaña says that 10 years on, she’s left with more questions than answers.

“I think that when you ask a research question that is successful as a question, it generates more questions, right?”

She goes on to say, “It became an even greater mystery,” adding, “It is also like a good novel, a good poem — something always remains.” Zetina Ocaña invokes Argentinian author Jorge Luis Borges, who likened the “aesthetic moment” to being left in a conversation that doesn’t end.

“And that is what I feel with this mural: That it is a conversation that opened up, and that we continue to have, and that I believe will give rise to other conversations.”