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On Monday, clearing a new area to extend Trench 5b produced a 20th-century artefact that we were able to quickly identify: a WWII-era rubber stopper with a moulded screw for sealing glass bottles. We can date it easily because the phrase WAR GRADE is moulded into the top.
During WWII, British rubber supplies were in danger as the Japanese expanded into Malaya and the Dutch East Indies. Sri Lanka became one of the last sources in Asia for British supply, while the Americans made deals with South American countries to import natural rubber. Massive rationing and recycling efforts were undertaken in the UK (and US) as evidenced by the British propaganda posters above. Experimentation in synthetic rubbers became a high priority as well. “War grade” was a designation for consumers to know that this material was an acceptable standard, but likely unable to be recycled. Apparently, the little cup in the top of the stopper was meant to use less rubber.
The object we found was very clearly made of rubber, but didn’t have any spring to it, which prompted a little further research into its composition and history. There seems to be some confusion over whether the bottle stopper is a synthetic rubber that underwent the process to make hard rubber similar to the process for vulcanite (the rubber, not the mineral) that in most cases involves natural rubber. Some collectors say it’s simply vulcanite, while other insist it was lower quality synthetics. Vulcanite was also under the brand name Ebonite from Goodyear. (The famed tyre manufacturers actually started their rubber revolution with buttons in the first half of the 19th century!)
Chemically, vulcanite began with natural India rubber that was vulcanised with sulphur. The process involves heat and sulphur facilitating links between polymers, which themselves are chains of big, repeating molecules. Different temperatures and additives can alter the elasticity, viscosity, conductivity/insulative properties, and strength of the resulting rubber. Vulcanisation is named for the Roman god Vulcan (Greek: Hephaestus) who represented fire and metallurgy. The original US patent for the process issued to Charles Goodyear’s team can be read here, whereas the UK patent was assigned to Thomas Hancock, who exposed the rubber to even higher temperatures forming proper vulcanite (the UK patent record has been a bit harder to track down). Hancock is the father of British rubber, with numerous patents including a shredder for rubber recycling. Both inventors and their further improvements continued parallel and roughly simultaneously beginning in the 1840s, while both sides claimed to have invented the process and resulting product independent of each other.
A Brief Interlude, a Digression, if you will…
In addition to claims of 19th-century corporate espionage, this particular compound had further associated scandal. While looking for more examples of vulcanite especially in its early days, we came across a page from the British Dental Association on vulcanite dentures that alluded to a juicier story of dentures, dentists, and murder. We would never deny you a digression as wild as this, so here is a New York Times article published 24 April, 1879 (it’s behind a paywall unfortunately, but we have a PDF view below). The Goodyear company had a treasurer of their dental division who served as a compliance officer named Josiah Bacon; he would go around to dentists who had failed to pay for the licence to use the technology. His archnemesis, dentist Samuel Chalfant, showed up at the hotel he was staying in and shot him dead.
Who knew there was so much drama over the intellectual property rights of rubber? Not us.
But back to the stoppers…
These particular stoppers however do go back to 1872, and for more information there is a lovely post from London-based mudlark (someone who salvages artefacts from rivers, bays, and shorelines) and artist Nicola White’s blog.
As our blog was being written, MORE bottle stoppers came out of both trenches Check them out below!