What happens when you need tires but lack the rubber with which to make them? Here’s a look at how life changed in Germany during World War I when the country was prevented from importing “black gold.”
Rubber, wrote Marcel Chausson in his doctoral thesis in 1912, is one of the “essential cogs of modern life.” Were it to suddenly disappear, “we would have to give up air brakes, bicycles and automobiles which, deprived of their tires, would be condemned to die on the spot. Electrical communications by overhead wire or cable would be interrupted; [there would be] no more electric light…”
Only a few years later, the outbreak of World War I provided an opportunity to test these claims. The unfortunate countries that served as the guinea pigs for this experiment were Germany and Austria-Hungary. Unlike Britain and France, they had no overseas colonies that could provide a steady yield of natural rubber. Prior to the war, in fact, Britain held a near-monopoly on the world’s rubber, while Germany imported nearly 100% of its supply.
This reliance on imports would come to prove devastating to Germany’s war effort. The British naval blockade, enacted shortly after the declaration of war in 1914, was aimed at weakening Germany and Austria-Hungary by preventing them from importing a variety of raw materials — including rubber. When Germany circumvented the blockade by purchasing rubber via neutral agents in London, the British government quickly moved to quash this possibility. Nevertheless, by late autumn of 1914, Germany had managed to stockpile enough rubber to last for a year.
As the war continued, however, the shortage of virgin natural rubber became more pronounced. To manage this finite supply, the German government employed three main strategies: use of alternative materials, development of synthetic rubber, and recycling of existing rubber objects.
To foreign observers, the shortage of rubber was most strikingly apparent in the lack of tires for vehicles. In New Zealand, newspapers reported the observations of “the managing director of a large rubber company” who had recently visited Berlin. He was astounded to see that “nearly all the taxicabs had steel tyres, the proprietors having no stocks of rubber tyres.” Residents of Vienna, meanwhile, saw their post office delivery cars and city buses outfitted with tires of wood, cork, felt, and iron. The wooden tires developed by Ludwig Spängler, director of the city’s streetcar network, received positive reviews in the press: “The tires cause very little noise, which hardly disturbs conversations in a closed carriage.…There is very little difference between these replacement and pneumatic tires, such that nothing stands in the way of the general introduction of the Spängler tire.”
These rosy descriptions and attempts to convince the public of the quality of rubber replacements sometimes stretched the bounds of credibility. For example, bicycle tires made of rattan were described as “a pleasant substitute for rubber tires due to their light weight, their elasticity and strength as well as their noiselessness while in operation.” In reality, many of the alternative tires— especially the metal ones—provided a less comfortable ride, made more noise, and destroyed roads. Austria eventually legislated a speed limit of 9 km/hour on paved roads in order to minimize damage from steel tires.
As early as the spring of 1915, the driving of private automobiles was banned in Germany in order to save tires and fuel. Three years later, the German emperor was said to be the only person in the country permitted to drive a car outfitted with pneumatic tires. Even top military commanders — Field Marshals von Hindenburg and Mackensen and General von Ludendorff — as well as the crown prince were “denied this luxury and compelled to bump along on tyres filled with rags, compressed cork, and paper.”
While the idea of paper tires may sound ridiculous nowadays, it was not out of place for its time. In 1907, the Carhart society in France promoted tires made of “bands of paper [that are] agglomerated by means of a chemical process and under enormous pressure.” Supposedly its resistance was “comparable to iron tires…furthermore, its elasticity is absolutely comparable to that of solid rubber. Its weight is the same as that of a pneumatic tire.”
That Germany should turn to paper tires is not altogether surprising. After all, paper was already demonstrating its versatility in other areas. A shortage of fabric meant that woven paper bandages eventually replaced textile bandages for wounded soldiers. The wool- and linen-starved country also turned to paper to clothe its citizens. As Sir Robert Cecil, Great Britain’s Minister for the Blockade, declared to the press in 1917, “The enemy is making clothes and boots of paper.” For all the benefits of paper tires as described by Carhart, however, they never did the job as well as rubber — and neither did tires of wood, steel, or cork. Thus, the development of synthetic rubber took on even more urgency and importance.
Even before the outbreak of the war in 1914, German scientists were trying to develop synthetic rubber. Already in 1908 Fritz Hofmann had discovered a way to make isoprene, a chemical building block in natural rubber; a year later, he patented a method for making synthetic rubber. In 1912, Carl Duisberg exhibited synthetic rubber tires at an international chemists’ conference in New York City. As the Bruce Herald reported in New Zealand at the time, “Though they represented the successful solution of one of the most difficult problems in chemistry, a long time would, he said, elapse before synthetic rubber could be made commercially profitable. He hoped to live to see that time, but synthetic rubber would ‘surely not be placed on the market in the near future.’”
A few years after Duisberg’s unveiling of his tires, one journalist gave this damning assessment of rubber substitutes: they had “not met with any great success…and [were] used for mixing with the rubber to cheapen it.” Germany’s challenge, therefore, lay in producing high-quality synthetic rubber at scale. Generally, the processes developed before the war do not seem to have been up to the task. As a French newspaper wrote with undisguised Schadenfreude in the spring of 1915, “What will they do next, since, as we have seen, neither Heinemann’s synthetic rubber, nor that of Doctor Harries, nor Fred. Bayer und Gesellschaft’s, can be of any use?” (Germany eventually settled on the Kondakov method, invented by a Russian in 1910, to make methyl rubber.)
Given these early disappointments in the development of synthetic rubber, relief and hope dominated the announcement, in December 1915, that “Louis Peter’s rubber factory has succeeded in producing the first automobile tire entirely from synthetic rubber. The tire is of excellent quality and durability.” The latter half of the statement probably contained more wishful thinking than truth. Several years later, the country was still short of rubber and synthetic replacements had not fulfilled their initial promise. “The strenuous efforts which German manufacturers have been making to produce synthetic rubber have been entirely unsuccessful,” wrote a Welsh newspaper in the spring of 1918. “They have, it is true, produced a material which they call by this name, but there is not a particle of rubber in it and its cost is quite fifteen times as much as vegetable rubber.” Similar news was reported in New Zealand: “Reports regarding Germany…are to the effect that…Synthetic rubber has been more or less of a failure.”
Due to the low quality of synthetic rubber, Germany and Austria-Hungary were always on the lookout for new sources of natural rubber. They entertained even the most fanciful alternatives. “Rubber from fish?” asked the Wiesbadener Zeitung in April 1915. The principle appeared to have grown out of the observation that glue in its fluid state shared some characteristics of rubber. A Dutch company was therefore attempting to create “an elastic substance similar to rubber” using the bones and cartilage of freshwater and saltwater fish. They combined boiling water with the fish and the resulting mixture was “treated with acids and alkalis and, after filtering, degassed with the addition of formaldehyde. As a result, the lecithin-containing proteins are completely separated out and a neutral product is formed.” Trials had not yet concluded, the newspaper added.
Scientists also explored alternative plant sources of natural rubber. Hevea brasiliensis trees could not survive outdoors in the climate of central Europe, but other latex-producing plants thrived there. Arpad Jakabíalvy, a pharmacist at the Austro-Hungarian army’s field hospital in Risano, Italy, suggested Euphorbia cyparissias, cypress spurge, which grew abundantly in the country. With no little enthusiasm, he enumerated the properties that euphorbia’s milky latex shared with rubber: “the elasticity, the adhesive force, the electrical wave insulation, the electricity generated by friction, the insolubility in water, the resistance to dilute acids, the solubility in gasoline.” Yet as Otto Lueger noted in 1920, cypress spurge lacks the efficiency of the larger hevea brasiliensis tree; many thousands of plants are needed to produce a single gram of rubber. Furthermore, like many of its euphorbia cousins, its latex irritates the skin. And even Jakabíalvy, despite his rhapsodic descriptions of cypress spurge growing wild in Hungarian meadows, admitted that one crucial challenge remained: “The main question has not yet been settled, namely whether the substance can be vulcanized.”
In the end, neither cypress spurge nor fish bones provided a realistic or timely solution to the crisis. Instead, Germany sought relief elsewhere: in the so-called “regeneration” of rubber.
In the 1840s, the discovery of vulcanization — the addition of sulphur to raw rubber under the influence of heat — proved a game-changer. Previously, deformation, stickiness, and a lack of heat resistance all plagued rubber objects. With vulcanization, however, rubber could be moulded and hardened into more permanent shapes, its durability much improved. Manufacturers of automobile and bicycle tires immediately took advantage of this new technology.
Almost immediately after the discovery of vulcanization, scientists attempted to reverse the process — to devulcanize, or desulphurize, the rubber in order to return it to its natural state. In the late nineteenth and early twentieth centuries, the process usually involved pulverizing the object and then submitting the powder to a chemical treatment. Moritz Körner’s patent from 1910 provides a typical description of the final product: “The india-rubber thus regenerated differs in no way from natural india-rubber as regards its property and can in particular be vulcanized again exactly like the latter.”
With a view to transforming old rubber into new items, the German government began requisitioning rubber items in 1915. Nothing was overlooked: the list of items to be declared to the authorities initially included dental rubber, car tires, rubberized textiles and bicycle inner tubes. Later, the list expanded to include garden hoses, rubber-soled shoes, and pram wheels. “From the old rubber doll, rubber ball, and torn rubber shoe, new car tires are made,” proclaimed the Kreis-Blatt für den Unter-Westwald-Kreis.
Before the war, the low quality of reclaimed rubber necessitated mixing it with new rubber. Contrary to the claims made by inventors of chemical devulcanization methods, the resulting rubber was not “perfectly plastic” or in a state to be “worked and used like the native gums.” As William K. Main explained in 1913, “The caoutchouc thus obtained is not completely regenerated, to tell the truth…It may be used in cheap mixed rubbers to make laboratory corks or washers for the joints of pipes. But rubber of good quality can never be recovered in this way.”
Wartime, however, changed the equation and beggars could not be choosers. Lacking fresh supplies with which to mix the regenerate, the German military had little choice but to accept lower-quality tires made entirely of recycled rubber. “These so-called ‘war tires,’” wrote the Casseler neueste Nachrichten in 1916, “are usable, even if they lack the durability of new tires.” Yet despite the functionality of these tires, metal and wood eventually came to dominate. Whether the lesser quality of recycled rubber or the eventual depletion of stocks of toys, hoses, and boots caused this shift is unclear. Whatever the case, the lack of high-grade tires hampered the German war effort: “With wood and steel tyres in place of rubber it has been necessary to reduce the speed in all cases…. The German army transport service has not been disorganised, but it has been rendered less efficient by reason of the great reduction in speed.”
This dearth of rubber may have contributed to Germany’s ultimate defeat. During the 1918 Spring Offensive, the army was unable to move quickly enough to sustain their territorial gains and reinforce their troops in the field. The crushing blow that Germany had hoped to deliver thus did not materialize. The Allies later regained the lost ground and breached German defenses across the front. Just a few months later, in November 1918, Germany agreed to an armistice.
The German Empire learned too late that its rubber supply chain lacked resiliency. Though Marcel Chausson’s apocalyptic predictions for a rubberless society did not come to pass, technological innovations failed to make up the shortfall between supply and demand. Civilians and soldiers both endured privations that sapped morale and affected the country’s ability to successfully prosecute the war.
We still face some of the same challenges as Germany did then. Although synthetic rubber has come into its own — 60% of the rubber used in the modern tire industry nowadays is synthetic — hevea brasiliensis still provides most of the world’s natural rubber. The threat of climate change, as well as hevea’s susceptibility to leaf blight, has accelerated the search for alternatives from other latex-producing plants. Scientists have experienced more success than Arpad Jakabíalvy with his cypress spurge. Continental, for example, recently released a tire made from dandelion rubber, while Bridgestone has produced a tire with rubber derived from the desert shrub guayule.
A high-quality, commercially available tire consisting of 100% recycled rubber remains as elusive in 2021 as it did in 1915. Slowly but surely, however, advances are being made. Lehigh uses a cryogenic turbo mill to produce micronized rubber powder, which can be used in tire manufacturing. Gecko has recently patented a method to make bicycle tires that contain up to 30% of recycled rubber. Meanwhile, Tyromer’s devulcanization process requires no chemicals and creates no waste by-products; KAL Tire, Canada’s largest tire retreading company, blends its tread compounds with 20% of Tyromer’s tire-derived polymer.
In sum, we now have synthetic rubber, alternative natural sources, and devulcanization available to us. Hopefully they will allow us to stave off the need for steel tires in the event of a future cataclysm.
With thanks to derekb, Interested, and JWK at the Great War Forum for their advice and research tips!