Hold the Maya: ancient pigments analysed

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  • Published: Jun 1, 2011
  • Author: David Bradley
  • Channels: UV/Vis Spectroscopy
thumbnail image: Hold the Maya: ancient pigments analysed

UV-Vis spectroscopy and various other techniques have been used to analyse the yellow pigments found in Mayan wall paintings. The compounds present are the indigoids, including isatin and dehydroindigo. The spectra together with SEM/EDX, TEM and voltammetry of microparticles show that this ancient people had the recipe for making indigo itself and converting it to Maya Blue and Maya Yellow in a stepwise reaction sequence.

The Maya considered blue to be the colour of the gods and for their rituals, art objects, and murals, they created the bold and beautiful pigment Maya blue by infusing indigo into the clay mineral palygorskite, a fibrous phyllosilicate containing magnesium and aluminium. Now, a team led by Antonio Doménech at the University of Valencia in Spain has discovered that some of the yellow pigments used by the Mayan people were based on similar components. As the scientists report in the journal Angewandte Chemie, the Maya appear to have developed a preparative technique that was not limited to Maya blue. Their technology pre-dates the modern synthesis of organic-inorganic hybrid materials, the team suggests.

Maya blue is a fascinating pigment, it is uniquely bright but can also range from a bright turquoise to a dark greenish blue. Chemists have always been fascinated by colour and research to understanding how particular colours arise in pigments from history and pre-history have been a particular focus for many teams. In the case of Mayan artefacts, researchers would like to know whether a particular colour stems from a unique organic components in the pigment, an unusual bonding pattern or some special physical production process.

Pigment production process

Doménech and colleagues María Teresa Doménech-Carbó, and María Luisa Vázquez de Agredos-Pascual have tested the various possibilities regarding the production of Mayan pigments. They surmise that the hue is determined by the ratio of indigo to the oxidised form dehydroindigo. This ratio, they explain, depends on how long the people making the pigment heated their formulation. Controlling the heating step would allow them to control the pigment hue while variations in how much mineral additive was used would also allow them to adjust the precise colour. Additionally, the researchers hypothesise that the Maya were also able to produce yellow and green pigments from the same indigo-based pigments in this way.

The team used visible and infrared spectroscopy and other techniques as well as microscopic methods and voltammetry of microparticles to identify the pigment in tiny samples from works of art. Specifically, they examined a series of yellow samples from Mayan murals from different archaeological sites in the Yucatán peninsula, Mexico. They say that their results confirm that a whole series of yellow pigments from Mayan mural paintings are made of indigoids bound to the mineral palygorskite. Also present in several of the samples was the well-known pigment ochre, hydrated iron(III) oxide, which is usually yellow to yellow-brown, although impurities also give rise to red ochre.

The researchers suggest that it is very likely that the preparation of pigments such as Maya yellow was produced in an intermediate step on the way to indigo and Maya blue preparation. Leaves and branches from indigo plants were probably soaked in a suspension of slaked lime in water and the coarse material filtered out, they say. A portion of the yellow suspension could then be removed and added to palygorskite to make Maya yellow. The remaining suspension would then be stirred vigorously until it took on a blue colour. It would then have been filtered and dried to release indigo for use as a dye. It could also be ground together with palygorskite and heated to produce Maya blue, the team says.


The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 UV-Vis spectroscopy and various other techniques have been used to analyse the yellow pigments found in Mayan wall paintings. The compounds present are the indigoids, including isatin and dehydroindigo.

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