Ancient ingredient that makes rubber balls bounce

26th Jan 2020

Mexicolore contributor Dr Nicholas Hellmuth

We are sincerely grateful to Dr. Nicholas Hellmuth, Founder, President, and Director of the Foundation for Latin American Anthropological Research (FLAAR) for writing this short introduction for us on the special ingredient without which rubber balls fail to bounce. Any youngster that plays Scalextric will be familiar with the bridge piece advertising Goodyear - long considered the person who discovered the process of ‘vulcanization’ of rubber tyres. He was actually very late on the scene...

If you collect sap from the Olmec and Maya native rubber tree (of Mexico, Guatemala, Belize, Honduras, etc), the latex from Castilla elastica is not yet rubber-like. To make latex sap become rubbery you have to add a chemical, boil it, and then the tree sap is “vulcanized.”
People in the USA are taught that Charles Goodyear invented vulcanization. But the Olmecs of Mexico discovered how to vulcanize rubber about 3000 years before any Gringo figured it out.
The Maya, Teotihuacan, Classic Veracruz (of El Tajin), the Zapotecs (of Monte Alban), the Toltecs, Mixtecs (of Oaxaca), Aztecs all knew how to vulcanize rubber centuries before either Charles Goodyear (USA) or Thomas Hancock (UK) claimed patents in the mid-1800’s.

There are at least three ‘coagulants’ that can turn the white latex sap of Castilla elastica into a functional bouncing rubber ball (you need only any one of the three; you don’t need more than one). The FLAAR Mesoamerica team working with CONAP and IDAEH park rangers found all three potential coagulants in Parque Nacional Yaxha Nakum Naranjo, Peten, Guatemala: Ipomoea alba, Merremia tuberosa, and Merremia umbellata. We grow two of these vines, Ipomoea alba and Merremia tuberosa 1500 meters above sea level in our FLAAR Mayan Ethnobotanical Research Garden in Guatemala City. It’s the resin from these vines, popularly known as ‘Morning Glory Vines’ that, when mixed with the resin of the rubber tree, coagulates the latex into bouncy rubber!
Ipomoea alba looks like all other Morning Glories, but blooms at night! So it’s commonly called Moon Flower; the popular name for Merremia tuberosa is wood rose.

In Guatemala Merremia tuberosa commonly grows near and even right next to Castilla elastica rubber trees. Literally, the two are happy in the same eco-system.
Ipomoea alba (Moonflower) vines grow a few kilometers away. So it would be great to start a project to see to what degree Merremia tuberosa can vulcanize rubber with the same efficiency as that already well documented for Ipomoea alba.

So people from anywhere in the world, if you want to learn about these pre-Hispanic coagulating plants, just visit Parque Nacional Yaxha Nakum Naranjo (pic 4). Ipomoea alba grows in front of the Hotel Ecolodge El Sombrero which is at the entrance to the park. You can ask for a boat and guide to take you to between Isla Topoxte and Rio Ixtinto to see the Merremia tuberosa. The other coagulant, Merremia umbellata, is in more remote aguada ecosystems near Nakum ruins (in the same park). Castilla elastica trees are in the park but you need a really experienced guide or park ranger to lead you to one. Dozens of rubber trees are near Tucuru, Alta Verapaz. Michael Tarkanian of MIT has accomplished field work in Chiapas and written an undergraduate thesis and MS thesis on Ipomoea alba and co-authored additional excellent research on Maya, Aztec, and Olmec rubber with MIT Professor Dorothy Hosler. We would enjoy cooperating with their team at MIT in the future, especially now that we have found the physical location of two more coagulants (known to earlier researchers but most previous focus has been on Ipomoea alba).

If local people plant the tree and both vines around their homes, they can form a village cooperative to make rubber balls to sell to tourists. ‘Mayan Rubber Balls from authentic Mayan Rubber Trees’ will become popular with visitors...
Rubber is useful for many more products than just game balls: rubber soles for sandals is a potential use. It would be worth doing research to make a list of what other items the Classic Maya could have used rubber for.

Picture sources:-
• Pic 1: image from the Codex Colombino scanned from our copy of the 1966 Sociedad Mexicana de Antropología, Mexico, facsimile edition
• Pix 2 & 3: photos by and courtesy of Nicholas Hellmuth/FLAAR
• Pic 4: photo by Russ Ford, downloaded from https://www.guatemala.com/guias/aventura/parques-nacionales-guatemala/parque-nacional-yaxha-peten-.html
• Pic 5: photo from Wikipedia (Mesoamerican rubber balls).

Fun science (it’s all about ‘contact forces’):-
• How high does a rubber ball bounce when we drop it? How high does it bounce when we throw it at the floor?
• When we drop a rubber ball, how many times does it bounce? Does the height the ball is dropped from affect the number of bounces?
• Can we find out how bouncy rubber is compared to other materials?

Learn more about the work of FLAAR