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No. 2342:
Maya Blue

Today, we have the blues. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Is it just the season? Why do I see blue all around me? My photos keep finding blue that I hadn't realized was there. Our black cat shimmers blue in the off-light of winter. Then my wife and I tripped over a far more horrific blue when we found Mel Gibson's movie Apocalypto on TV and decided to watch it.

It's about the Mayas just before the Spanish arrive -- bucolic protagonists captured by a powerful city state and marched off to be used as human sacrifices. But first, their bodies are painted a rich blue color. If you saw Gibson's movie Braveheart you might wonder if he has a thing about painting bodies blue. Well, perhaps he does; but that blue really was part of Mayan sacrificial ritual. 

The Mayas gave to blue, the color of water, a special place. It appears in their murals and pottery, and they used it to placate their rain god Chaak. They used it to paint the humans the sacrificed to invoke rain. For 1200 years, before the Spanish came, the Mayas farmed in their dry climates, and rain was critical. 

They created their remarkable pigment, Maya blue, by combining indigo dye with a clay called palygorskite. The clay binds the dye and protects it in a durable blue paint. Palygorskite, by the way, is an aluminum-magnesium-silicon compound with medicinal properties. It makes an excellent anti-diarrhea medicine.

This blue paint turned up in a macabre setting back in 1904 when anthropologist Edward Thompson dredged a water-filled sinkhole at Chichén Itzá. The Mayans called these deep and inaccessible sinkholes, cenotes. And this one was sacred. Not all blue-painted sacrifices died under the knife. Many were cast into this Sacred Cenote along with valuable goods -- also painted blue.

The stunning part of Thompson's discovery was a fourteen-foot deep layer of blue sediment at the bottom. That took a lot of blue paint to create. Now anthropologists from Wheaton College and Chicago's Field Museum have been studying this paint and what they've found adds yet a new wrinkle to an ancient practice. 

They believe that the Mayas made their paint by heating three healing elements: In addition to palygorskite and indigo, they used copal incense as a binding agent. They're pretty certain that they made the paint on the spot as part of the ritual itself.

But then, creating the color blue has always been a challenge worthy of ritual. Neolithic cave painters were never able to make it. Medieval book illustrators would grind up precious lapis lazuli to get it. When, in the 18th century, people stumbled across potassium ferric cyanide, they began making the brilliant Prussian Blue paints. Germany discovered aniline dyes in the mid 19th century, then built an industrial nation upon their production.

Blue, being precious, holds special, but highly inconsistent places in our many cultures. It is the color of virtue, the color of calm, the color of water, and lastly -- the color of sadness. (Well, sad indeed for so many hapless Mayas.)

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Maya blue has been the subject of widely reported recent work. See, e.g., this press release.

See also, this online account of archaeological studies of Maya blue.

And this more detailed account of the structure of the pigment.

After this aired, I received emails reminding me that I'd neglected to mention the last LED color to be created -- also blue.

a number of blues