Anyone who has lived in the Maya world for any time at all knows that the Maya are magicians with color. One of puzzlements of the historical Maya has been how they created a blue color that was more resistant to fading than most natural pigments. The historical Maya used this color on ceramics and, because it recalled the rain god Chac, in their sacrifices.
It has been known that two of the ingredients were indigo plant extract and a clay called palygorskite. But “Nobody has ever really figured out how those two key ingredients were fused into a very stable pigment,” according to Gary Feinman, curator of anthropology at the Field Museum in Chicago. Now Feinman, together with Dean E. Arnold, professor of anthropology at Wheaton College, believe they have figured out the secret of the ancient Maya concoction.
“We think that copal, the sacred incense, may have been a third ingredient,” says Feinman. “Heat and perhaps copal resin were the keys to fusing the indigo extract and the clay mineral.”