rubber

Tough elastic substance which is obtained from the latex of the rubber tree. Its name was bestowed by the British scientist Joseph Priestley after he discovered its ability to erase or ‘rub out’ pencil marks. Rubber is collected from trees which trunks are gouged, causing the sap to run down into a tap that then drips into a small cup (fig.), a process known as rubber tapping. In South America where the tree is a native, Indians call it ‘cachuchu’, the wood that weeps. The cut must be made perfect, as the yield would drop dramatically when the wound is too deep or not deep enough. Every tree is scored afresh every 2-3 nights, before sunrise and when it doesn't rain. After the cutting, the collecting starts, emptying all small cups into buckets. This has to be done hastily, before the rubber begins to harden. Once the sun rises it's too late: the rubber would harden, be spoiled and useless (fig.). After collecting the crude rubber it is transferred into large barrels, diluted with water and treated with acid to coagulate the particles. Then, it is poured into pans to harden (fig.), after which it is trampled on by barefooted workers, to expand the surface and compress the matter a first time, before being mangled into white, pliable sheets or mats, that are then hung to dry in the sun (fig.). While drying, they turn yellowish-beige (fig.). In history, Indians were using rubber long before its introduction to Western civilization. It wasn't until 1736, when explorer Charles Condamine sent back home several rolls of crude rubber produced by Indians from wild trees in the Amazon Valley, that scientists got gradually interested. Long before its commercial application had been discovered the British industrialist Samual Peal found cloth could be waterproofed by rubbing it with a solution of rubber and turpentine. In 1839, the American inventor Charles Goodyear discovered that if you vulcanized rubber by cooking it with sulfur it would no longer become stiff in cold weather or sticky and smelly in the heat. This chemical process of vulcanization, in which natural rubber is converted into a more durable material by adding sulfur, was named after Vulcan, the ancient Roman god of fire. South America remained the first source of crude rubber until 1876 when the Briton Sir Henry Wickham germinated around 70,000 hevea brasiliensis seeds smuggled from Brazil and successfully planted them in Ceylon. Soon after rubber trees were planted in Malaysia as well. When in the beginning of the 20th century tin supplies on the island of Phuket declined Thailand got in on the act, planting its first rubber tree in 1903. King Rama V also assigned a new governor to Trang province to set out local rubber production there and by 1936 Thailand was producing 4% of the world rubber market. The end of the boom began with the outbreak of WW II when a cost effective way to produce synthetic rubber was devised, but Thailand still produces around 2 million tons of rubber a year, worth some 60 billion baht and making it the world's biggest producer of crude rubber. In a good year the yield could be as much as 500 kilograms of raw rubber per hectare. Besides its surgical and aviation uses, rubber is used in a variety of products, from elastic bands to car parts, etc. Also called para rubber. 回