Tips for Maintaining a New Car

This is why tyres are black in cars & other vehicles

Tyre technology has come a long way since the Ford Model T first rolled out of the factory in 1908. Modern tyres are not only different in dimension, compound, and overall structure, but they’re also a different color. That’s because early tyres were white, and only around World War I, did they turn black. Here’s why.

I suppose I should say what started me down this path, as tyre color probably isn’t something anyone thinks about much. When my dad came to visit Detroit back in March, I took him to the Ford Piquette Avenue Plant Museum, the first Ford-owned factory, and the hallowed spot where the Model T was conceived and initially assembled.

“Original tyres had a lighter shade because of the natural color of rubber,” a company representative told me. “Carbon black [a fine manufactured soot] was added to the rubber compound in [circa 1917] and produced a tenfold increase in wear resistance.”

This increased longevity is confirmed by award-winning chemical engineer Jack Koenig, who says in his book Spectroscopy of Polymers that a tyre without carbon black would last “less than 5,000 miles.” Consider that most tyres are driven between 12,000 and 15,000 miles a year and are meant to last three or four years or more, and you get how low that was.

Tyre company Coker also gives credit for tyres’ black appearance to carbon black in a blog post titled “The History and Timeline of Whitewall Tyres”, mentioning that the strengthening properties of carbon black are key. Goodyear’s Hug the Road blog also mentions improved resistance to ozone and increased conductivity to help transfer heat away from the tread and belts as benefits key to the blackening material.

So now it’s worth asking:

What Is Carbon Black?

Photo: Orion Engineered Carbons

Carbon black is the product of a hydrocarbon that has gone through incomplete combustion, and whose “smoke” has been captured as fine black particles consisting almost entirely of elemental carbon.

But in the 1870s, as noted in the thrilling tome Developments in Rubber Technology, Volume 1, came a breakthrough called the channel process. Essentially, it involved burning natural gas up against water-cooled H-shaped metal channels and collecting the carbon deposits. This new process, and specifically the finer particles it yielded, was apparently an important step in yielding stronger tyres for the auto industry, as Orion Engineered Carbons writes in its brochure:

But channel black wasn’t particularly efficient or environmentally friendly, as you can see in the below picture of the stuff getting made. These were called “hot houses,” and their smoke could be seen for miles.

Photo: Orion Engineered Carbons

Today, the primary method of obtaining carbon black is called the “furnace process,” which involves taking a heavy oil or natural gas feedstock, and injecting it into a furnace wherein natural gas and pre-heated air have combusted (see image below). The high temperatures of this reaction cause the feedstock to “crack” and turn into smoke, which is cooled by water and filtered out as tiny carbon black bits from the gas.

Image from: Orion Engineered Materials Brochure

Carbon black powder is extremely fine, and to see the true shape of the material requires the use of an electron microscope, which reveals tiny particles, generally between 10 nanometers and 500 nanometers, that have fused together into chains of various shapes. According to major carbon black manufacturer Birla Carbon, the size of the particles, as well as that of the fused-together “aggregates,” and overall shape affects things like a rubber’s abrasion resistance, tensile strength, blackness, conductivity, and weatherability.

Photo: Mitsubishi Chemical

Different grades of carbon black tend to be categorized based on their surface area, as well as on their effect on the cure rate of rubber. Here’s a look at a number of different grades, which are used for a variety of different rubber applications like motor mounts, conveyor belts, and high-performance tyres.

How a World War I Supply Shortage Could Be The Reason for Black Tyres

Photo: B.F. Goodrich via Model T Ford Club of America

The history of how tyres got their black color is complex and fascinating, but also a bit murky. I spoke with Jack Seavitt, a member of the board of trustees and also a tour guide at the Ford Piquette plant. While he later admitted that he and his colleagues had different stories on how it all went down, his take was that tyres may have turned black as a result of a World War I munitions shortage.

In particular, he said that in the early 1900s, tyre makers figured out that they could add magnesium oxide to rubber to increase strength. “But magnesium oxide was needed in the munitions industry during World War I,” he told me, saying it was used as a propellant, and that brass for artillery shells was also in short supply. “So they said to the automotive industry: You can’t use brass anymore, and you can’t use magnesium oxide in tyres.”

Image: Binney & Smith via magazine-advertisements.com

A bit of browsing on the internet brought me to Crayola, makers of crayons and markers. Crayola used to be a brand under the company Binney & Smith, named after Edwin Binney and C. Harold Smith. These two were the son and nephew, respectively, of Joseph Binney, founder of New York-based Peekskill Chemical Works, which sold charcoal and lampblack—the aforementioned deep black powder obtained by collecting soot deposits from burning oil. It was used to make pigments and inks.

Image: Binney & Smith via Printing Art, Volume 17

After Joseph retired and Edwin and C. Harold started Binney & Smith, the company became known for red oxide paint, which was used to decorate barns throughout America, and after the turn of the century, Binney & Smith introduced innovations like dustless chalk for classrooms and affordable crayons branded “Crayola.” More importantly, by this time, Binney & Smith had become a world leader in the production of natural gas-based carbon black, selling it as ink under the “Peerless” brand, which won a gold award at the 1900 Paris Exposition.

Image: BF Goodrich via periodpaper.com

According to an article written in 1992 in the American Society for Testing and Materials’ newspaper Standardization News by a Michelin quality guarantee manager, Thomas Hancock—founder of the British rubber industry—and Charles Goodyear—discoverer of the vulcanization process—had patents from the 1830s dealing with adding lampblack to rubber for coloring, but it wasn’t until later that tyres actually changed color.

The author, Jeffery A. Melsom, says the true rubber-strengthening benefits of carbon black was discovered by S.C. Mote, a chemist for the Silvertown, England-based India Rubber, Gutta Percha and Telegraph Cable Company, in 1904.

So, where does World War I come in? Well, Jack Seavitt from the Ford Piquette plant may have had a point about a munitions shortage, though I think he mixed up magnesium oxide with zinc oxide. I say he might have had a point because I came upon a December, 1988 issue of Fortune Magazine that mentions a munitions shortage:

The market for carbon black exploded after World War I. Until then zinc oxide reinforced the rubber in tyres. When the production of brass for shell casings consumed the available zinc, chemists chanced on carbon black, which worked even better.

I also came across this paragraph in Reinforced Plastics magazine:

The date of this discovery is quite ominous as this occurred on the eve of the start of World War I. Zinc oxide had been used as a reinforcing agent in tyres, however, zinc is a component of brass and was needed for bullets, munition, and armament components. This set the stage for carbon black to move from a small black pigment business to a global industrial specialty chemical business. The volume of carbon black supplied to the market sextupled from 1915 to 1924 as a result of this new innovation…

And there’s this passage from the book The World Rubber Industry, which discusses why carbon black in tyres didn’t catch on until well after its benefits were discovered, in part because of weak tyre structures being tyres’ major failure points, not rubber tread:

…tyre carcasses at the time were so weak that improving the tread alone offered little benefit. But then the improvement of tyre carcasses through cord casing, the great upsurge in tyre consumption, and the shortage in the First World War of the zinc oxide previously employed for tyre reinforcement, facilitated increased use of black, and demonstrated its superiority.

Michelin’s spokesperson told me the company’s first black tyres, launched around 1917, were called “Universal Tread Covers,” and were advertised as tyres built for “all roads and all weathers.”

So it’s not totally clear how much World War I factored into tyres becoming black, as it appears that knowledge of carbon black’s strengthening power had existed well prior, as did a vast supply of the microscopic black particles thanks in part to Binney & Smith and the Pennsylvania oil rush.

It seems like a bit of a convergence. At the same time, cars were becoming widespread in the first years of mass production, and tyres were becoming strong enough to make long-lasting carbon black reinforcement worthwhile, and other chemical alternatives were restricted during the war.

Still, the fact is that starting just around World War I, carbon black took over from zinc oxide, and tyres became black. But more importantly, they became more durable, and still, keep that color to this day.

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