Vulcanite screw design bottle stopper.
The screw design bottle stopper was patented by Henry Barrett in 1880; he also designed the internal screw thread for the interiors of bottle necks. The design was in use between the 1880s - 1970s. The stoppers themselves are made from hard, non-elastic, India rubber, also known as vulcanite. The process of “vulcanisation” involved heating rubber to 115 degrees Celsius with sulphur and also linseed oil – thereby converting it into a more durable material. The stoppers are also sometimes described as being made from ebonite, which in fact was the brand name for the vulcanised rubber – patented by Charles Goodyear in 1846.
