Ancient #Maya masons had a smart way to make #plaster stronger

Up close, the Mayas' timeless recipe from #Copán looks similar to mother-of-pearl.

By Rahul Rao, Apr 19, 2023

[Recent discoveries] "seemed to confirm past archaeological and written records suggesting that ancient Maya masons mixed plant matter into their plaster. The other standard ingredients (lime and water) wouldn’t account for complex carbon chains.

"To follow this lead, the authors decided to make the historic plaster themselves. They consulted living #masons and Maya descendants near #Copán. The locals referred them to the #chukum and #jiote #trees that grow in the surrounding #forests—specifically, the sap that came from the trees’ bark.

"The authors tested the sap’s reaction when mixed into the plaster. Not only did it toughen the material, it also made the plaster insoluble in water, which partly explains how Copán survived the local climate so well.

"The microscopic structure of the plant-enhanced plaster is similar to nacre or mother-of-pearl: the iridescent substance that some molluscs create to coat their shells. We don’t fully understand how #molluscs make nacre, but we know that it consists of crystal plates sandwiching elastic proteins. The combination toughens the sea creatures’ exteriors and reinforces them against weathering from waves.

"A close study of the ancient plaster samples and the modern analog revealed that they also had layers of rocky calcite plates and organic sappy material, giving the materials the same kind of resilience as nacre. 'They were able to reproduce what living organisms do,' says Rodríguez Navarro."
#IndigenousKnowledge #IndigenousNews #Honduras

Source: https://www.popsci.com/science/ancient-maya-plaster/