Production
In Northern Europe, the word "tar" refers primarily to a substance that is derived from the wood and roots of pine. In earlier times it was often used as a water repellent coating for boats, ships, and roofs. It is still used as an additive in the flavoring of candy, alcohol and other foods. Wood tar is microbicidal and has a pleasant odor – a sweet musky scent much like that of barbecue. Producing tar from wood was known in ancient Greece, and has probably been used in Scandinavia since the Iron Age. For centuries, dating back at least to the 14th century, tar was among Sweden's most important exports. Sweden exported 13,000 barrels of tar in 1615 and 227,000 barrels in the peak year of 1863. Production nearly stopped in the early 20th century, when other chemicals replaced tar and wooden ships were replaced by steel ships.
The heating (dry distilling) of pine wood causes tar and pitch to drip away from the wood and leave behind charcoal. Birchbark is used to make particularly fine tar, known as "Russian oil", suitable for leather protection. The by-products of wood tar are turpentine and charcoal. When deciduous tree woods are subjected to destructive distillation the products are methanol (wood alcohol) and charcoal.
Tar kilns (Swedish: tjärdal, Danish: tjæremile, Norwegian: tjæremile, Finnish: tervahauta) are dry distillation ovens, historically used in Scandinavia for producing tar from wood. They were built close to the forest, from limestone or from more primitive holes in the ground. The bottom is sloped into an outlet hole, to allow the tar to pour out. The wood is split to dimensions of a finger and stacked densely, and finally covered tight with dirt and moss. If oxygen can enter, the wood might catch fire, and the production would be ruined. On top of this, a fire is stacked and lit. After a few hours, the tar starts to pour out, and continues to do so for a few days.
Read more about this topic: Tar
Famous quotes containing the word production:
“[T]he asphaltum contains an exactly requisite amount of sulphides for production of rubber tires. This brown material also contains “ichthyol,” a medicinal preparation used externally, in Webster’s clarifying phrase, “as an alterant and discutient.””
—State of Utah, U.S. public relief program (1935-1943)
“The growing of food and the growing of children are both vital to the family’s survival.... Who would dare make the judgment that holding your youngest baby on your lap is less important than weeding a few more yards in the maize field? Yet this is the judgment our society makes constantly. Production of autos, canned soup, advertising copy is important. Housework—cleaning, feeding, and caring—is unimportant.”
—Debbie Taylor (20th century)
“The production of obscurity in Paris compares to the production of motor cars in Detroit in the great period of American industry.”
—Ernest Gellner (b. 1925)