Elastic Marvels: The Resilient World of Rubber Trees


Tuvia Cohen 


We don’t want to worry you, but we have a little problem. You see, we have this rather large 350-ton jumbo jet that has requested permission to land. There are no other aircraft in the area, so we can easily give permission. The airplane has wheels, and plenty of them, so no difficulties there. The problem is that the captain of the jumbo has not yet decided what material to place around the metal rim of those numerous and ponderous wheels. 

You have to visualize the situation to appreciate the scope of the problem. A jumbo jet is enormous, and as it descends from the sky to meet the ground, it is traveling at some 200 miles an hour. As contact is made between the wheel rim and concrete, the friction created is intense. So quickly, suggest what he can use! Should he wrap the rims with sacking, a material that is usually very hard-wearing? It will rip to shreds in a second. Should he clothe the wheels in leather? The jolt caused by the impact will snap off the wheels as easily as a fragile twig. Perhaps he should simply leave the wheels in their pristine steel? Could you imagine the steel wheel carving a trench in the concrete, with sparks pouring forth, each spark posing the gravest risk? We have to find the solution, and quickly! 

While I think, my mind tires. Tires? You mean tires? That’s it! Rubber tires – the perfect solution. An inflated ring of rubber that covers the rim of the wheel will absorb the impact, and it is strong, durable, waterproof, and flexible. Problem solved – what a relief!  


Could We Manage Without Rubber? 

Imagine that you had to describe this substance called rubber to a newcomer to Earth. What would you say? “Well, it’s sort of black and elasticated, you know, like . . . rubber!” But where does it grow, how is it made, who discovered it, why do we need it, and could we ever manage without it?  

The answer to the last question is a definite “no,” as anyone who has ever traveled in a car, plane, or bicycle will attest. Imagine the level of discomfort as you ride – or rather bounce and jolt – along the highway at 70 mph in a car with wheels bound by metal! As for the first questions, prepare to be amazed. 

Why is rubber so useful? There are many reasons. It holds air (as in your balloon), it keeps out moisture (as in your rubber boots), it does not readily conduct electricity (which explains its widespread use in insulation), and is a poor conductor of heat (making it an excellent choice of materials for coating the handles of frying pans). But its chief importance to us is that it is elastic. In fact, rubber can be made so elastic that it will stretch to more than nine times its normal length. When you stretch a rubber band and let it go, its elasticity makes it quickly spring back to its original shape. A rubber ball, that mainstay of children’s games, bounces because of this same springiness. Your rubber heels are wonderful shock absorbers because of their elasticity.  

Fantastic stuff, rubber, but where does it come from?  


Columbus, the Indians, and Goodyear Tires 

When the early European explorers came to Central and South America, they saw the Indians playing with bouncing balls made out of rubber. According to an early Spanish historian, Columbus found the Indians using balls “made from the gum of a tree.” The explorers learned that the Indians made “waterproof” shoes from latex, the milky white juice of the rubber tree. They spread the latex on their feet, and let it dry. Those same Indians also made waterproof bottles by smoothing latex on a bottle-shaped clay mold. They dried the latex over a fire, and then washed out the clay. It was not until the 18th century that two French scientists spent several years doing botanical research in South America. In 1730, one of them, Monsieur Francois Fresneau, made a full report about rubber, and was the first scientist to describe the rubber tree. Another major breakthrough took place in 1823, when a Scottish manufacturer, Charles Macintosh, had a brilliant idea for raincoats. He rubberized two pieces of cloth with dissolved rubber, and pressed them together, making a sort of cloth sandwich with a rubber filling. Although these coats became popular, they were not perfect, as the rain leaked in at the seams, and in hot weather, the rubber leaked out. 

While Mr. Macintosh was trying to perfect his raincoats, an American by the name of Charles Goodyear was attempting to produce rubber that would be unaffected by changes of temperature. Then, one day in 1839, he accidentally placed a mixture of rubber, white lead, and sulfur on a hot stove. When he removed it, he found that the rubber could still be stretched, but had not become gummy. Thus, he discovered the process known as vulcanization, whereby sulfur is heated with rubber, resulting in a compound that remains tough and firm in both heat and cold. Vulcanized rubber was elastic, airtight, and watertight, and could be used to make tight seals between the moving parts of machinery. The rubber industry had begun. 


The Mystery of Latex 

So much for the work of man. But what of the actual substance, and the trees from which it stems?  

Latex is found in a wide variety of trees and other plants, but some aspects of latex still remain a mystery. Scientists know that latex is not a sap, but they are not sure of its use to the plant. There are those who think that latex acts as a kind of protective substance when a plant has been harmed. But if this is the case, why do some trees have latex in super abundance (such as the rubber tree) and so many have none? As we shall see, the answer is that the Creator of the Universe knew that mankind would need rubber, so He created latex! 

The milky liquid called latex consists of about 30 to 35 percent pure rubber. Water accounts for another 60-65 percent, with the remainder consisting of resins, proteins, and sugar. The latex holds tiny globules (particles) of rubber in the same way that milk holds butterfat. The rubber tree grows best in hot, moist climates. The latex that contains the rubber flows through a series of tubes in the layer of the tree directly under the bark. When this layer is pierced, the latex oozes out. 

Plantation workers, called “tappers,” begin work at daybreak, because the latex flows most freely in the cool morning air. The tapper removes a thin shaving of bark with a tool shaped so that the bottom of the groove forms a channel. The groove slants diagonally downward about halfway around the trunk. At the bottom of the cut, the tapper attaches a U- shaped metal spout, and below that, a small cup. The latex oozes from the inner bark, and flows down the channel into a collecting cup. Don’t feel sorry for the cut bark – as the latex dries, it seals the cut! Each tapper works on about 350 trees on one round of tapping, which takes him about three hours. After tapping the last tree, the tapper makes a second round to collect the latex, removing the dried latex and making a fresh cut.  

Rubber trees yield their full capacity of latex for about 25-30 years.  

What is most amazing is that after about three or four years, the grooves in the tree reach the ground. The tapper then goes to the other side of the tree, and begins cutting the bark there. By the time the second set of grooves reaches the ground, the bark has grown back on the first grooves, and it is ready to be tapped again! 


Thank Gd for Rubber! 

Rubber is a wonder product. We depend on it so much that it would be almost impossible to manage without it. It is the only material that is elastic, airtight, water resistant, shock absorbing, and resilient. Manufacturers make between 40,000 and 50,000 rubber products. A typical car has about 600 rubber parts. Think of waterproof aprons, boots, raincoats, hot-water bottles, ice bags, elastic bands, bathing caps, goggles, rubber life-rafts, golf balls, tennis balls, bottle stoppers, rubber gloves, and shoe soles. How could we manage without rubber? Our whole transport system is dependent on rubber. More than half the rubber used in the world goes into tires and tubes, which in turn are fitted onto cars, airplanes, bicycles, trucks, tractors, and construction machinery. Modern society would quite literally grind to a halt without this amazing “fruit” of the rubber tree. 

Everything that Gd created was done so for a purpose. The Creator of the Universe knew that one day mankind would require the services and qualities of rubber – and so He created the rubber tree with its ever-flowing latex to satisfy that need. Thank you, Hashem!