Next, the researchers analysed the ancient plaster from the Honduras site and prepared a replica of it. The process of making plaster involves baking (calcinating) carbonate rock material such as limestone using hot temperatures, before adding water to the resulting quicklime, forming a lime paste which is mixed with sand. As the material hardens it sucks carbon dioxide from the air, trapping it in the calcite cement. The researchers also took the advice of the stone masons and added juice
from the bark of Chucúm and Jiote trees to the mix. They found that the resulting plaster was especially hardy and durable.
"We were able to exactly replicate the structure, texture and mechanical properties of the ancient material," says Rodriguez-Navarro.