MesoAmericans vulcanised rubber 3000 years before Goodyear

ERJ staff report (DS)

Boston Massachusetts - New research from the Massachusetts Institute of Technology indicates that meso-Americans were able to vulcanise rubber and also to compound it for different applications.

According to the research by Professor Dorothy Hosler and Technical Instructor Michael Tarkanian of MIT's Department of Materials Science and Engineering, were most likely achieved by varying the proportions of the two basic ingredients, latex from rubber trees and juice from morning-glory vines, which were cooked together. A paper describing the findings will be published soon in the journal Latin American Antiquity.

The MIT paper claims that the Meso-Americans had the technology to compound for different applications -- even if they did not necessarily use that kowledge. For the soles of their sandals, they could have made a strong, wear-resistant version. For the rubber balls used in the games that were a central part of their religious ceremonies, they may have processed it for maximum bounciness. And for rubber bands and adhesives used for ornamental wear and for attaching blades to shafts, they might have produced rubber optimised for resilience and strength.

Although Hosler and Tarkanian's research demonstrates that the Mesoamericans had the raw materials and the basic knowledge to make these different formulations, proving that's what they actually did would require further evidence, either from contemporaneous accounts or from chemical analysis of samples used for different purposes.

Until the new research, nobody had shown that it was possible to obtain the different properties needed for other uses of rubber, simply by varying the recipe's proportions. Unlike the rubber balls, Mesoamerican rubber-soled sandals have never been found. But they are described in the diaries of the Spanish explorers and missionaries, and their existence is clear from linguistic evidence: The Aztecs used a compound word that clearly blends the words for “rubber” and “sandals.”

The ancient rubber material that has survived is so degraded that it can't be tested for its mechanical properties. So Tarkanian and Hosler set up their own processing facility at MIT, using raw materials collected in field trips to Mexico. They made batches of rubber with varying proportions of the two plant substances, and then subjected the product to a suite of tests to measure wear resistance, elasticity, toughness and other properties.

Sure enough, varying the proportions produced different properties. A 50-50 blend of the latex and morning glory produced maximum elasticity, or bounciness, perfect for the rubber balls. Rubber used as an adhesive or for joining other materials (such as ceramic and wood) needs different properties - strength and damping ability - and for that, pure latex seems to work best. For sandals, where wear resistance is the most important quality, a three-to-one mix of latex to morning glory provides the most durable material.

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Press release from MIT