First, the binational team of conservation scientists tested the paper, called amate, which is made from the inner bark of a fig tree. They carried out studies of spectroscopy and X-ray fluorescence to determine the elemental composition of the material. They didn’t find any modern substances in the amate fibers. The paper was indeed authentic.
But that only solved part of the mystery. Some scientists and academics argued that the codex could be a forgery produced in the 1960s using authentic pre-Columbian paper. So, the team went further. Photomacrography and photomicrography examined the edges of the paper and discovered that it was not cut with metal tools, as a modern forgery would be.
“Every test was helpful to solve a new piece of the puzzle,” said Gutiérrez. “But since the biggest question mark was that it could be a forgery using old paper, we had to find something to study separately from the paper.”
According to Gutiérrez: “The remaining components would be the stucco layer on top of the paper used as a base for painting, the pigments, and the geological residues. We couldn’t separate the stucco without harming the fragile document, and if we analyzed natural pigments or soil, we would only end up tracing their source in nature. So, we had to find something human-made, synthetic.”
A study of the last viable components, the pigments, was the only thing standing in the way of settling a decades-long debate. But not every pigment was a good candidate for examination. Most used in the codex were natural: brown-red cochineal, iron mineral red, and charcoal black. This made them unsuitable, because the tests would lead back to where the pigments were extracted, not the time from when they were used to paint the codex.
In order to figure out the date of the codex’s origin, scientists needed to be able to find something that the creators (or forgers) had modified. “And we found it in a pool of green-blue color called Maya blue,” said Gutiérrez, with a triumphant smile.
Maya blue is not only a synthetic pigment but also one that is special, because it has a history that can be traced. To make Maya blue, explained Gutiérrez, “Maya artists combined blue dye extracted from indigo plants with a specific type of clay called palygorskite, creating one of the most durable colors humanity has ever developed.”
“The knowledge of how to create this Maya blue was lost,” said Gutiérrez, “and the first time it was successfully re-created in a soluble form to be used as paint was in a laboratory in the United States in 1966.”
So, for the codex to be fake, the forgers would have needed to have access to Maya blue before 1965, when Sáenz bought the book.
With that, the study was concluded, and Sáenz’s much-debated codex was not only authenticated but also dated to 1021–1154 CE, making it the oldest surviving pre-Hispanic book produced in the Americas.
Códice Maya de México was updated from the category of “ethnographic artifact” to an “archaeological object—heritage of Mexico” by INAH and is now included in the UNESCO Memory of the World Register, a compendium of the world’s documentary heritage, as a component of the Collection of Mexican Codices of the Biblioteca Nacional de Antropología e Historia.
In October 2022 the Getty Museum will present the first viewing of Códice Maya de México in the United States in the 21st century.
Andrew Turner, curator of the exhibition and senior research specialist at the Getty Research Institute, shared his excitement for this show, which he has spent 15 years researching. “Although often overlooked, the fields of art history and science can overlap as they did for the authentication of Códice Maya de México,” he said. “We hope visitors will see Getty as a place where that happens too.”
