The Romance of Rubber
There are probably a few myths interwoven into this tale, but a brief history of the development of the tyre industry wouldn’t be complete without a tribute to the early pioneers of the rubber industry.
First there had to be a source of the material itself. The tree hevea braziliensis, the name gives a clue where it was from, bled a milky liquid sap (called latex), which when dried in the sun and smoked, became rubber. The South American “Indians” used to wrap this sticky material up into shapes approximating a football, and kick it around, so that’s where football came from?
The early explorers returned to Europe with this interesting material, but really couldn’t find a use for it except as a curiosity because of its bounce, and it found use as a pencil eraser, hardly earth shattering.
A Scotsman discovered that it dissolved in petroleum based solvents, and could be spread on fabric to make water-proofed clothing, called “macintoshes”, but these stuck together if they became warm, so of limited use. Later, a means of “cold vulcanisation” by dipping the fabric in chemicals was developed. Cold vulcanisation is still used today, most commonly in puncture repair kits
Enter Charles Goodyear, around the 1840’s. He was a “chemical tinkerer” according to legend, and experimented with many materials as an additive to rubber, trying to convert it into something more useful. Eventually he struck pay-dirt by combining rubber with sulphur, and cooking it under pressure. Pressure had to be applied to prevent the material becoming porous. By combining sulphur and rubber, an irreversible chemical change was initiated which made the product stronger and retained its elasticity. Combining it with a much larger percentage of sulphur (around 35%) gave a very hard material called ebonite, which immediately found applications. It was the forerunner of modern plastics, in a way.
Nearly fifty years later, John Boyd Dunlop wrapped his bicycle wheels with proofed fabric, inflated the resulting tube with air, and started winning bike races because pneumatic tyres were easier to push than bicycles shod with solid tyres. This was in 1888, four years before the first Daimler-Benz was made, called Mercedes after his daughter. The bicycle tyre industry took off, as the bicycle was the most popular individual form of transport. Components to manufacture bicycle tyres were shipped from the U.K. to South Melbourne as early as 1892 for assembly here, so you can see that the take-up was rapid worldwide.
The introduction of the motor car changed everything. Many entrepreneurs started building cars, and despite their many limitations, pneumatic tyres were quickly adopted on them, (though truck tyres continued on solid tyres for many years afterwards.) This occurred most rapidly in the U.S.A., and the Seiberling brothers started a tyre company, calling it after Charles Goodyear, and another famous name of the period was Harvey Firestone. Both names survive today. Goodyear built the first factory of theirs outside the U.S.A. in Sydney in 1927 at Granville.
You may think of the radial tyre as a recent invention, but Gray and Sloper invented the design in the early 1900’s, but couldn’t figure out a way of stabilising the construction, nor the means of building it.
The 1920’s saw many rapid advances in the technology of rubber. The make up of the various formulations was a closely guarded company secret. Materials were coded to disguise their identity, and factories were closed to visitors. In some, communication between departments of the same factory was restricted. In some companies today, these practices still survive, though the means to chemically analyse the complete structure of a rubber compound exist.
Around that time in the 1920’s, chemicals were being developed that speeded up the vulcanisation process markedly, and others that delayed rubber from “perishing”. Some of these proved to be pretty toxic and were later withdrawn, but left an unfortunate legacy behind.
A story of the time tells of a clergyman visitor who was admitted to counsel one of his flock, and who expressed great wonderment at what he was seeing, and asked for a sample of rubber being processed. When approved, he drew out his pocket knife to cut a sample, and LICKED IT FIRST. He was immediately escorted out the door, because he knew too much, that wet rubber cuts easily. . So industrial espionage is not new either!
Entry filed under: Tyre Technology. Tags: charles goodyear, daimler-benz, granville, harvey firestone, hevea braziliensis, john boyd dunlop, latexsulphur, seiberling, sloper, south american, vulcanisation.