22/04/13 Mayan Blue Pigment Recipe Revealed In New Chemical Analysis Of Ancient Paint

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Mayan Blue Pigment Recipe Revealed In New ChemicalAnalysis Of Ancient Paint

By: Megan Gannon, News Editor Published: 04/03/2013 09:09 AM EDT on LiveScience

The ancient Maya used a vivid, remarkably durable blue paint to cover their palace walls, codices, pottery and maybe even the bodies ofhuman sacrifices who were thrown to their deaths down sacred wells. Now a group of chemists claim to have cracked the recipe of MayaBlue.

Scientists have long known the two chief ingredients of the intense blue pigment: indigo, a plant dye that's used today to color denim; andpalygorskite, a type of clay. But how the Maya cooked up the unfading paint remained a mystery. Now Spanish researchers report that theyfound traces of another pigment in Maya Blue, which they say gives clues about how the color was made.

Maya Blue on an ancient Maya mural. Scientists have solved the mystery of how the Maya concocted

this pigment. Photo: Constantino Reyes / Azulmaya.com

"We detected a second pigment in the samples, dehydroindigo, which must have formed throughoxidation of the indigo when it underwent exposure to the heat that is required to prepare Maya Blue,"Antonio Doménech, a researcher from the University of Valencia, said in a statement.

"Indigo is blue and dehydroindigo is yellow, therefore the presence of both pigments in variableproportions would justify the more or less greenish tone of Maya Blue," Doménech explained. "It ispossible that the Maya knew how to obtain the desired hue by varying the preparation temperature, forexample heating the mixture for more or less time or adding more of less wood to the fire."

American researchers in 2008 claimed that copal resin, which was used for incense, may have been thethird secret ingredient for Maya Blue. Their research was based on a study of a bowl that had traces of thepigment and was used to burn incense. But Doménech's team didn't buy those findings. [Image Gallery:Stunning Mayan Murals]

"The bowl contained Maya Blue mixed with copal incense, so the simplified conclusion was that it was onlyprepared by warming incense," Doménech said in a statement.

The Spanish researchers say they are now investigating the chemical bonds that bind the paint's organic component (indigo) to theinorganic component (clay), which is key to Maya Blue's resilience.

Among the more remarkable discoveries of the paint in context was a 14-foot thick (4 meters) layer of blue mud at the bottom of a naturallyformed sinkhole, called the Sacred Cenote, at the famous Pre-Columbian Maya site Chichén Itzá in the Yucatán Peninsula of Mexico. Whenthe Sacred Cenote was first dredged in 1904, it puzzled researchers, but some scientists now believe it was probably left over from blue-coated human sacrifices thrown into the well as part of a Maya ritual.

The research was detailed this year in the journal Microporous and Mesoporous Materials.

Follow Megan Gannon on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on LiveScience.com.

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April 22, 201 3

Posted: 04/03/2013 9:59 am EDT | Updated: 04/03/2013 10:27 am EDT

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22/04/13 Mayan Blue Pigment Recipe Revealed In New Chemical Analysis Of Ancient Paint

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